SDK for Go V2 を使用した DynamoDB の例 - AWS SDK コード例

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SDK for Go V2 を使用した DynamoDB の例

次のコード例は、DynamoDB で AWS SDK for Go V2 を使用してアクションを実行し、一般的なシナリオを実装する方法を示しています。

アクションはより大きなプログラムからのコードの抜粋であり、コンテキスト内で実行する必要があります。アクションは個々のサービス機能を呼び出す方法を示していますが、関連するシナリオやサービス間の例ではアクションのコンテキストが確認できます。

「シナリオ」は、同じサービス内で複数の関数を呼び出して、特定のタスクを実行する方法を示すコード例です。

各例には、 へのリンクが含まれています。このリンクには GitHub、コンテキスト内でコードをセットアップして実行する方法の手順が記載されています。

アクション

次の例は、BatchExecuteStatement を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

INSERT ステートメントのバッチを使用して項目を追加します。

// AddMovieBatch runs a batch of PartiQL INSERT statements to add multiple movies to the // DynamoDB table. func (runner PartiQLRunner) AddMovieBatch(movies []Movie) error { statementRequests := make([]types.BatchStatementRequest, len(movies)) for index, movie := range movies { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year, movie.Info}) if err != nil { panic(err) } statementRequests[index] = types.BatchStatementRequest{ Statement: aws.String(fmt.Sprintf( "INSERT INTO \"%v\" VALUE {'title': ?, 'year': ?, 'info': ?}", runner.TableName)), Parameters: params, } } _, err := runner.DynamoDbClient.BatchExecuteStatement(context.TODO(), &dynamodb.BatchExecuteStatementInput{ Statements: statementRequests, }) if err != nil { log.Printf("Couldn't insert a batch of items with PartiQL. Here's why: %v\n", err) } return err }

SELECT ステートメントのバッチを使用して項目を取得します。

// GetMovieBatch runs a batch of PartiQL SELECT statements to get multiple movies from // the DynamoDB table by title and year. func (runner PartiQLRunner) GetMovieBatch(movies []Movie) ([]Movie, error) { statementRequests := make([]types.BatchStatementRequest, len(movies)) for index, movie := range movies { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year}) if err != nil { panic(err) } statementRequests[index] = types.BatchStatementRequest{ Statement: aws.String( fmt.Sprintf("SELECT * FROM \"%v\" WHERE title=? AND year=?", runner.TableName)), Parameters: params, } } output, err := runner.DynamoDbClient.BatchExecuteStatement(context.TODO(), &dynamodb.BatchExecuteStatementInput{ Statements: statementRequests, }) var outMovies []Movie if err != nil { log.Printf("Couldn't get a batch of items with PartiQL. Here's why: %v\n", err) } else { for _, response := range output.Responses { var movie Movie err = attributevalue.UnmarshalMap(response.Item, &movie) if err != nil { log.Printf("Couldn't unmarshal response. Here's why: %v\n", err) } else { outMovies = append(outMovies, movie) } } } return outMovies, err }

UPDATE ステートメントのバッチを使用して項目を更新します。

// UpdateMovieBatch runs a batch of PartiQL UPDATE statements to update the rating of // multiple movies that already exist in the DynamoDB table. func (runner PartiQLRunner) UpdateMovieBatch(movies []Movie, ratings []float64) error { statementRequests := make([]types.BatchStatementRequest, len(movies)) for index, movie := range movies { params, err := attributevalue.MarshalList([]interface{}{ratings[index], movie.Title, movie.Year}) if err != nil { panic(err) } statementRequests[index] = types.BatchStatementRequest{ Statement: aws.String( fmt.Sprintf("UPDATE \"%v\" SET info.rating=? WHERE title=? AND year=?", runner.TableName)), Parameters: params, } } _, err := runner.DynamoDbClient.BatchExecuteStatement(context.TODO(), &dynamodb.BatchExecuteStatementInput{ Statements: statementRequests, }) if err != nil { log.Printf("Couldn't update the batch of movies. Here's why: %v\n", err) } return err }

DELETE ステートメントのバッチを使用して項目を削除します。

// DeleteMovieBatch runs a batch of PartiQL DELETE statements to remove multiple movies // from the DynamoDB table. func (runner PartiQLRunner) DeleteMovieBatch(movies []Movie) error { statementRequests := make([]types.BatchStatementRequest, len(movies)) for index, movie := range movies { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year}) if err != nil { panic(err) } statementRequests[index] = types.BatchStatementRequest{ Statement: aws.String( fmt.Sprintf("DELETE FROM \"%v\" WHERE title=? AND year=?", runner.TableName)), Parameters: params, } } _, err := runner.DynamoDbClient.BatchExecuteStatement(context.TODO(), &dynamodb.BatchExecuteStatementInput{ Statements: statementRequests, }) if err != nil { log.Printf("Couldn't delete the batch of movies. Here's why: %v\n", err) } return err }

この例で使用している Movie struct を定義します。

// Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }
  • API の詳細については、「 API リファレンスBatchExecuteStatement」の「」を参照してください。 AWS SDK for Go

次の例は、BatchWriteItem を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // AddMovieBatch adds a slice of movies to the DynamoDB table. The function sends // batches of 25 movies to DynamoDB until all movies are added or it reaches the // specified maximum. func (basics TableBasics) AddMovieBatch(movies []Movie, maxMovies int) (int, error) { var err error var item map[string]types.AttributeValue written := 0 batchSize := 25 // DynamoDB allows a maximum batch size of 25 items. start := 0 end := start + batchSize for start < maxMovies && start < len(movies) { var writeReqs []types.WriteRequest if end > len(movies) { end = len(movies) } for _, movie := range movies[start:end] { item, err = attributevalue.MarshalMap(movie) if err != nil { log.Printf("Couldn't marshal movie %v for batch writing. Here's why: %v\n", movie.Title, err) } else { writeReqs = append( writeReqs, types.WriteRequest{PutRequest: &types.PutRequest{Item: item}}, ) } } _, err = basics.DynamoDbClient.BatchWriteItem(context.TODO(), &dynamodb.BatchWriteItemInput{ RequestItems: map[string][]types.WriteRequest{basics.TableName: writeReqs}}) if err != nil { log.Printf("Couldn't add a batch of movies to %v. Here's why: %v\n", basics.TableName, err) } else { written += len(writeReqs) } start = end end += batchSize } return written, err } // Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }
  • API の詳細については、「 API リファレンスBatchWriteItem」の「」を参照してください。 AWS SDK for Go

次の例は、CreateTable を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // CreateMovieTable creates a DynamoDB table with a composite primary key defined as // a string sort key named `title`, and a numeric partition key named `year`. // This function uses NewTableExistsWaiter to wait for the table to be created by // DynamoDB before it returns. func (basics TableBasics) CreateMovieTable() (*types.TableDescription, error) { var tableDesc *types.TableDescription table, err := basics.DynamoDbClient.CreateTable(context.TODO(), &dynamodb.CreateTableInput{ AttributeDefinitions: []types.AttributeDefinition{{ AttributeName: aws.String("year"), AttributeType: types.ScalarAttributeTypeN, }, { AttributeName: aws.String("title"), AttributeType: types.ScalarAttributeTypeS, }}, KeySchema: []types.KeySchemaElement{{ AttributeName: aws.String("year"), KeyType: types.KeyTypeHash, }, { AttributeName: aws.String("title"), KeyType: types.KeyTypeRange, }}, TableName: aws.String(basics.TableName), ProvisionedThroughput: &types.ProvisionedThroughput{ ReadCapacityUnits: aws.Int64(10), WriteCapacityUnits: aws.Int64(10), }, }) if err != nil { log.Printf("Couldn't create table %v. Here's why: %v\n", basics.TableName, err) } else { waiter := dynamodb.NewTableExistsWaiter(basics.DynamoDbClient) err = waiter.Wait(context.TODO(), &dynamodb.DescribeTableInput{ TableName: aws.String(basics.TableName)}, 5*time.Minute) if err != nil { log.Printf("Wait for table exists failed. Here's why: %v\n", err) } tableDesc = table.TableDescription } return tableDesc, err }
  • API の詳細については、「 API リファレンスCreateTable」の「」を参照してください。 AWS SDK for Go

次の例は、DeleteItem を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // DeleteMovie removes a movie from the DynamoDB table. func (basics TableBasics) DeleteMovie(movie Movie) error { _, err := basics.DynamoDbClient.DeleteItem(context.TODO(), &dynamodb.DeleteItemInput{ TableName: aws.String(basics.TableName), Key: movie.GetKey(), }) if err != nil { log.Printf("Couldn't delete %v from the table. Here's why: %v\n", movie.Title, err) } return err } // Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }
  • API の詳細については、「 API リファレンスDeleteItem」の「」を参照してください。 AWS SDK for Go

次の例は、DeleteTable を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // DeleteTable deletes the DynamoDB table and all of its data. func (basics TableBasics) DeleteTable() error { _, err := basics.DynamoDbClient.DeleteTable(context.TODO(), &dynamodb.DeleteTableInput{ TableName: aws.String(basics.TableName)}) if err != nil { log.Printf("Couldn't delete table %v. Here's why: %v\n", basics.TableName, err) } return err }
  • API の詳細については、「 API リファレンスDeleteTable」の「」を参照してください。 AWS SDK for Go

次の例は、DescribeTable を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // TableExists determines whether a DynamoDB table exists. func (basics TableBasics) TableExists() (bool, error) { exists := true _, err := basics.DynamoDbClient.DescribeTable( context.TODO(), &dynamodb.DescribeTableInput{TableName: aws.String(basics.TableName)}, ) if err != nil { var notFoundEx *types.ResourceNotFoundException if errors.As(err, &notFoundEx) { log.Printf("Table %v does not exist.\n", basics.TableName) err = nil } else { log.Printf("Couldn't determine existence of table %v. Here's why: %v\n", basics.TableName, err) } exists = false } return exists, err }
  • API の詳細については、「 API リファレンスDescribeTable」の「」を参照してください。 AWS SDK for Go

次の例は、ExecuteStatement を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

INSERT ステートメントを使用して項目を追加します。

// AddMovie runs a PartiQL INSERT statement to add a movie to the DynamoDB table. func (runner PartiQLRunner) AddMovie(movie Movie) error { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year, movie.Info}) if err != nil { panic(err) } _, err = runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("INSERT INTO \"%v\" VALUE {'title': ?, 'year': ?, 'info': ?}", runner.TableName)), Parameters: params, }) if err != nil { log.Printf("Couldn't insert an item with PartiQL. Here's why: %v\n", err) } return err }

SELECT ステートメントを使用して項目を取得します。

// GetMovie runs a PartiQL SELECT statement to get a movie from the DynamoDB table by // title and year. func (runner PartiQLRunner) GetMovie(title string, year int) (Movie, error) { var movie Movie params, err := attributevalue.MarshalList([]interface{}{title, year}) if err != nil { panic(err) } response, err := runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("SELECT * FROM \"%v\" WHERE title=? AND year=?", runner.TableName)), Parameters: params, }) if err != nil { log.Printf("Couldn't get info about %v. Here's why: %v\n", title, err) } else { err = attributevalue.UnmarshalMap(response.Items[0], &movie) if err != nil { log.Printf("Couldn't unmarshal response. Here's why: %v\n", err) } } return movie, err }

SELECT ステートメントを使用して、項目のリストを取得し、結果を射影します。

// GetAllMovies runs a PartiQL SELECT statement to get all movies from the DynamoDB table. // pageSize is not typically required and is used to show how to paginate the results. // The results are projected to return only the title and rating of each movie. func (runner PartiQLRunner) GetAllMovies(pageSize int32) ([]map[string]interface{}, error) { var output []map[string]interface{} var response *dynamodb.ExecuteStatementOutput var err error var nextToken *string for moreData := true; moreData; { response, err = runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("SELECT title, info.rating FROM \"%v\"", runner.TableName)), Limit: aws.Int32(pageSize), NextToken: nextToken, }) if err != nil { log.Printf("Couldn't get movies. Here's why: %v\n", err) moreData = false } else { var pageOutput []map[string]interface{} err = attributevalue.UnmarshalListOfMaps(response.Items, &pageOutput) if err != nil { log.Printf("Couldn't unmarshal response. Here's why: %v\n", err) } else { log.Printf("Got a page of length %v.\n", len(response.Items)) output = append(output, pageOutput...) } nextToken = response.NextToken moreData = nextToken != nil } } return output, err }

UPDATE ステートメントを使用して項目を更新します。

// UpdateMovie runs a PartiQL UPDATE statement to update the rating of a movie that // already exists in the DynamoDB table. func (runner PartiQLRunner) UpdateMovie(movie Movie, rating float64) error { params, err := attributevalue.MarshalList([]interface{}{rating, movie.Title, movie.Year}) if err != nil { panic(err) } _, err = runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("UPDATE \"%v\" SET info.rating=? WHERE title=? AND year=?", runner.TableName)), Parameters: params, }) if err != nil { log.Printf("Couldn't update movie %v. Here's why: %v\n", movie.Title, err) } return err }

DELETE ステートメントを使用して項目を削除します。

// DeleteMovie runs a PartiQL DELETE statement to remove a movie from the DynamoDB table. func (runner PartiQLRunner) DeleteMovie(movie Movie) error { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year}) if err != nil { panic(err) } _, err = runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("DELETE FROM \"%v\" WHERE title=? AND year=?", runner.TableName)), Parameters: params, }) if err != nil { log.Printf("Couldn't delete %v from the table. Here's why: %v\n", movie.Title, err) } return err }

この例で使用している Movie struct を定義します。

// Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }
  • API の詳細については、「 API リファレンスExecuteStatement」の「」を参照してください。 AWS SDK for Go

次の例は、GetItem を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // GetMovie gets movie data from the DynamoDB table by using the primary composite key // made of title and year. func (basics TableBasics) GetMovie(title string, year int) (Movie, error) { movie := Movie{Title: title, Year: year} response, err := basics.DynamoDbClient.GetItem(context.TODO(), &dynamodb.GetItemInput{ Key: movie.GetKey(), TableName: aws.String(basics.TableName), }) if err != nil { log.Printf("Couldn't get info about %v. Here's why: %v\n", title, err) } else { err = attributevalue.UnmarshalMap(response.Item, &movie) if err != nil { log.Printf("Couldn't unmarshal response. Here's why: %v\n", err) } } return movie, err } // Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }
  • API の詳細については、「 API リファレンスGetItem」の「」を参照してください。 AWS SDK for Go

次の例は、ListTables を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // ListTables lists the DynamoDB table names for the current account. func (basics TableBasics) ListTables() ([]string, error) { var tableNames []string var output *dynamodb.ListTablesOutput var err error tablePaginator := dynamodb.NewListTablesPaginator(basics.DynamoDbClient, &dynamodb.ListTablesInput{}) for tablePaginator.HasMorePages() { output, err = tablePaginator.NextPage(context.TODO()) if err != nil { log.Printf("Couldn't list tables. Here's why: %v\n", err) break } else { tableNames = append(tableNames, output.TableNames...) } } return tableNames, err }
  • API の詳細については、「 API リファレンスListTables」の「」を参照してください。 AWS SDK for Go

次の例は、PutItem を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // AddMovie adds a movie the DynamoDB table. func (basics TableBasics) AddMovie(movie Movie) error { item, err := attributevalue.MarshalMap(movie) if err != nil { panic(err) } _, err = basics.DynamoDbClient.PutItem(context.TODO(), &dynamodb.PutItemInput{ TableName: aws.String(basics.TableName), Item: item, }) if err != nil { log.Printf("Couldn't add item to table. Here's why: %v\n", err) } return err } // Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }
  • API の詳細については、「 API リファレンスPutItem」の「」を参照してください。 AWS SDK for Go

次の例は、Query を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // Query gets all movies in the DynamoDB table that were released in the specified year. // The function uses the `expression` package to build the key condition expression // that is used in the query. func (basics TableBasics) Query(releaseYear int) ([]Movie, error) { var err error var response *dynamodb.QueryOutput var movies []Movie keyEx := expression.Key("year").Equal(expression.Value(releaseYear)) expr, err := expression.NewBuilder().WithKeyCondition(keyEx).Build() if err != nil { log.Printf("Couldn't build expression for query. Here's why: %v\n", err) } else { queryPaginator := dynamodb.NewQueryPaginator(basics.DynamoDbClient, &dynamodb.QueryInput{ TableName: aws.String(basics.TableName), ExpressionAttributeNames: expr.Names(), ExpressionAttributeValues: expr.Values(), KeyConditionExpression: expr.KeyCondition(), }) for queryPaginator.HasMorePages() { response, err = queryPaginator.NextPage(context.TODO()) if err != nil { log.Printf("Couldn't query for movies released in %v. Here's why: %v\n", releaseYear, err) break } else { var moviePage []Movie err = attributevalue.UnmarshalListOfMaps(response.Items, &moviePage) if err != nil { log.Printf("Couldn't unmarshal query response. Here's why: %v\n", err) break } else { movies = append(movies, moviePage...) } } } } return movies, err } // Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }
  • API の詳細については、「AWS SDK for Go API リファレンス」の「Query」を参照してください。

次の例は、Scan を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // Scan gets all movies in the DynamoDB table that were released in a range of years // and projects them to return a reduced set of fields. // The function uses the `expression` package to build the filter and projection // expressions. func (basics TableBasics) Scan(startYear int, endYear int) ([]Movie, error) { var movies []Movie var err error var response *dynamodb.ScanOutput filtEx := expression.Name("year").Between(expression.Value(startYear), expression.Value(endYear)) projEx := expression.NamesList( expression.Name("year"), expression.Name("title"), expression.Name("info.rating")) expr, err := expression.NewBuilder().WithFilter(filtEx).WithProjection(projEx).Build() if err != nil { log.Printf("Couldn't build expressions for scan. Here's why: %v\n", err) } else { scanPaginator := dynamodb.NewScanPaginator(basics.DynamoDbClient, &dynamodb.ScanInput{ TableName: aws.String(basics.TableName), ExpressionAttributeNames: expr.Names(), ExpressionAttributeValues: expr.Values(), FilterExpression: expr.Filter(), ProjectionExpression: expr.Projection(), }) for scanPaginator.HasMorePages() { response, err = scanPaginator.NextPage(context.TODO()) if err != nil { log.Printf("Couldn't scan for movies released between %v and %v. Here's why: %v\n", startYear, endYear, err) break } else { var moviePage []Movie err = attributevalue.UnmarshalListOfMaps(response.Items, &moviePage) if err != nil { log.Printf("Couldn't unmarshal query response. Here's why: %v\n", err) break } else { movies = append(movies, moviePage...) } } } } return movies, err } // Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }
  • API の詳細については、「AWS SDK for Go API リファレンス」の「Scan」を参照してください。

次の例は、UpdateItem を使用する方法を説明しています。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // UpdateMovie updates the rating and plot of a movie that already exists in the // DynamoDB table. This function uses the `expression` package to build the update // expression. func (basics TableBasics) UpdateMovie(movie Movie) (map[string]map[string]interface{}, error) { var err error var response *dynamodb.UpdateItemOutput var attributeMap map[string]map[string]interface{} update := expression.Set(expression.Name("info.rating"), expression.Value(movie.Info["rating"])) update.Set(expression.Name("info.plot"), expression.Value(movie.Info["plot"])) expr, err := expression.NewBuilder().WithUpdate(update).Build() if err != nil { log.Printf("Couldn't build expression for update. Here's why: %v\n", err) } else { response, err = basics.DynamoDbClient.UpdateItem(context.TODO(), &dynamodb.UpdateItemInput{ TableName: aws.String(basics.TableName), Key: movie.GetKey(), ExpressionAttributeNames: expr.Names(), ExpressionAttributeValues: expr.Values(), UpdateExpression: expr.Update(), ReturnValues: types.ReturnValueUpdatedNew, }) if err != nil { log.Printf("Couldn't update movie %v. Here's why: %v\n", movie.Title, err) } else { err = attributevalue.UnmarshalMap(response.Attributes, &attributeMap) if err != nil { log.Printf("Couldn't unmarshall update response. Here's why: %v\n", err) } } } return attributeMap, err } // Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }
  • API の詳細については、「 API リファレンスUpdateItem」の「」を参照してください。 AWS SDK for Go

シナリオ

次のコードサンプルは、以下の操作方法を示しています。

  • 映画データを保持できるテーブルを作成する。

  • テーブルに 1 つの映画を入れ、取得して更新する。

  • サンプル JSON ファイルから映画データをテーブルに書き込む。

  • 特定の年にリリースされた映画を照会する。

  • 何年もの間にリリースされた映画をスキャンする。

  • テーブルからムービーを削除し、テーブルを削除します。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

対話型シナリオを実行してテーブルを作成し、そのテーブルに対してアクションを実行します。

// RunMovieScenario is an interactive example that shows you how to use the AWS SDK for Go // to create and use an Amazon DynamoDB table that stores data about movies. // // 1. Create a table that can hold movie data. // 2. Put, get, and update a single movie in the table. // 3. Write movie data to the table from a sample JSON file. // 4. Query for movies that were released in a given year. // 5. Scan for movies that were released in a range of years. // 6. Delete a movie from the table. // 7. Delete the table. // // This example creates a DynamoDB service client from the specified sdkConfig so that // you can replace it with a mocked or stubbed config for unit testing. // // It uses a questioner from the `demotools` package to get input during the example. // This package can be found in the ..\..\demotools folder of this repo. // // The specified movie sampler is used to get sample data from a URL that is loaded // into the named table. func RunMovieScenario( sdkConfig aws.Config, questioner demotools.IQuestioner, tableName string, movieSampler actions.IMovieSampler) { defer func() { if r := recover(); r != nil { fmt.Printf("Something went wrong with the demo.") } }() log.Println(strings.Repeat("-", 88)) log.Println("Welcome to the Amazon DynamoDB getting started demo.") log.Println(strings.Repeat("-", 88)) tableBasics := actions.TableBasics{TableName: tableName, DynamoDbClient: dynamodb.NewFromConfig(sdkConfig)} exists, err := tableBasics.TableExists() if err != nil { panic(err) } if !exists { log.Printf("Creating table %v...\n", tableName) _, err = tableBasics.CreateMovieTable() if err != nil { panic(err) } else { log.Printf("Created table %v.\n", tableName) } } else { log.Printf("Table %v already exists.\n", tableName) } var customMovie actions.Movie customMovie.Title = questioner.Ask("Enter a movie title to add to the table:", []demotools.IAnswerValidator{demotools.NotEmpty{}}) customMovie.Year = questioner.AskInt("What year was it released?", []demotools.IAnswerValidator{demotools.NotEmpty{}, demotools.InIntRange{ Lower: 1900, Upper: 2030}}) customMovie.Info = map[string]interface{}{} customMovie.Info["rating"] = questioner.AskFloat64( "Enter a rating between 1 and 10:", []demotools.IAnswerValidator{ demotools.NotEmpty{}, demotools.InFloatRange{Lower: 1, Upper: 10}}) customMovie.Info["plot"] = questioner.Ask("What's the plot? ", []demotools.IAnswerValidator{demotools.NotEmpty{}}) err = tableBasics.AddMovie(customMovie) if err == nil { log.Printf("Added %v to the movie table.\n", customMovie.Title) } log.Println(strings.Repeat("-", 88)) log.Printf("Let's update your movie. You previously rated it %v.\n", customMovie.Info["rating"]) customMovie.Info["rating"] = questioner.AskFloat64( "What new rating would you give it?", []demotools.IAnswerValidator{ demotools.NotEmpty{}, demotools.InFloatRange{Lower: 1, Upper: 10}}) log.Printf("You summarized the plot as '%v'.\n", customMovie.Info["plot"]) customMovie.Info["plot"] = questioner.Ask("What would you say now?", []demotools.IAnswerValidator{demotools.NotEmpty{}}) attributes, err := tableBasics.UpdateMovie(customMovie) if err == nil { log.Printf("Updated %v with new values.\n", customMovie.Title) for _, attVal := range attributes { for valKey, val := range attVal { log.Printf("\t%v: %v\n", valKey, val) } } } log.Println(strings.Repeat("-", 88)) log.Printf("Getting movie data from %v and adding 250 movies to the table...\n", movieSampler.GetURL()) movies := movieSampler.GetSampleMovies() written, err := tableBasics.AddMovieBatch(movies, 250) if err != nil { panic(err) } else { log.Printf("Added %v movies to the table.\n", written) } show := 10 if show > written { show = written } log.Printf("The first %v movies in the table are:", show) for index, movie := range movies[:show] { log.Printf("\t%v. %v\n", index+1, movie.Title) } movieIndex := questioner.AskInt( "Enter the number of a movie to get info about it: ", []demotools.IAnswerValidator{ demotools.InIntRange{Lower: 1, Upper: show}}, ) movie, err := tableBasics.GetMovie(movies[movieIndex-1].Title, movies[movieIndex-1].Year) if err == nil { log.Println(movie) } log.Println(strings.Repeat("-", 88)) log.Println("Let's get a list of movies released in a given year.") releaseYear := questioner.AskInt("Enter a year between 1972 and 2018: ", []demotools.IAnswerValidator{demotools.InIntRange{Lower: 1972, Upper: 2018}}, ) releases, err := tableBasics.Query(releaseYear) if err == nil { if len(releases) == 0 { log.Printf("I couldn't find any movies released in %v!\n", releaseYear) } else { for _, movie = range releases { log.Println(movie) } } } log.Println(strings.Repeat("-", 88)) log.Println("Now let's scan for movies released in a range of years.") startYear := questioner.AskInt("Enter a year: ", []demotools.IAnswerValidator{ demotools.InIntRange{Lower: 1972, Upper: 2018}}) endYear := questioner.AskInt("Enter another year: ", []demotools.IAnswerValidator{ demotools.InIntRange{Lower: 1972, Upper: 2018}}) releases, err = tableBasics.Scan(startYear, endYear) if err == nil { if len(releases) == 0 { log.Printf("I couldn't find any movies released between %v and %v!\n", startYear, endYear) } else { log.Printf("Found %v movies. In this list, the plot is <nil> because "+ "we used a projection expression when scanning for items to return only "+ "the title, year, and rating.\n", len(releases)) for _, movie = range releases { log.Println(movie) } } } log.Println(strings.Repeat("-", 88)) var tables []string if questioner.AskBool("Do you want to list all of your tables? (y/n) ", "y") { tables, err = tableBasics.ListTables() if err == nil { log.Printf("Found %v tables:", len(tables)) for _, table := range tables { log.Printf("\t%v", table) } } } log.Println(strings.Repeat("-", 88)) log.Printf("Let's remove your movie '%v'.\n", customMovie.Title) if questioner.AskBool("Do you want to delete it from the table? (y/n) ", "y") { err = tableBasics.DeleteMovie(customMovie) } if err == nil { log.Printf("Deleted %v.\n", customMovie.Title) } if questioner.AskBool("Delete the table, too? (y/n)", "y") { err = tableBasics.DeleteTable() } else { log.Println("Don't forget to delete the table when you're done or you might " + "incur charges on your account.") } if err == nil { log.Printf("Deleted table %v.\n", tableBasics.TableName) } log.Println(strings.Repeat("-", 88)) log.Println("Thanks for watching!") log.Println(strings.Repeat("-", 88)) }

この例で使用している Movie struct を定義します。

// Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }

DynamoDB アクションを呼び出す構造体およびメソッドを作成します。

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples. // It contains a DynamoDB service client that is used to act on the specified table. type TableBasics struct { DynamoDbClient *dynamodb.Client TableName string } // TableExists determines whether a DynamoDB table exists. func (basics TableBasics) TableExists() (bool, error) { exists := true _, err := basics.DynamoDbClient.DescribeTable( context.TODO(), &dynamodb.DescribeTableInput{TableName: aws.String(basics.TableName)}, ) if err != nil { var notFoundEx *types.ResourceNotFoundException if errors.As(err, &notFoundEx) { log.Printf("Table %v does not exist.\n", basics.TableName) err = nil } else { log.Printf("Couldn't determine existence of table %v. Here's why: %v\n", basics.TableName, err) } exists = false } return exists, err } // CreateMovieTable creates a DynamoDB table with a composite primary key defined as // a string sort key named `title`, and a numeric partition key named `year`. // This function uses NewTableExistsWaiter to wait for the table to be created by // DynamoDB before it returns. func (basics TableBasics) CreateMovieTable() (*types.TableDescription, error) { var tableDesc *types.TableDescription table, err := basics.DynamoDbClient.CreateTable(context.TODO(), &dynamodb.CreateTableInput{ AttributeDefinitions: []types.AttributeDefinition{{ AttributeName: aws.String("year"), AttributeType: types.ScalarAttributeTypeN, }, { AttributeName: aws.String("title"), AttributeType: types.ScalarAttributeTypeS, }}, KeySchema: []types.KeySchemaElement{{ AttributeName: aws.String("year"), KeyType: types.KeyTypeHash, }, { AttributeName: aws.String("title"), KeyType: types.KeyTypeRange, }}, TableName: aws.String(basics.TableName), ProvisionedThroughput: &types.ProvisionedThroughput{ ReadCapacityUnits: aws.Int64(10), WriteCapacityUnits: aws.Int64(10), }, }) if err != nil { log.Printf("Couldn't create table %v. Here's why: %v\n", basics.TableName, err) } else { waiter := dynamodb.NewTableExistsWaiter(basics.DynamoDbClient) err = waiter.Wait(context.TODO(), &dynamodb.DescribeTableInput{ TableName: aws.String(basics.TableName)}, 5*time.Minute) if err != nil { log.Printf("Wait for table exists failed. Here's why: %v\n", err) } tableDesc = table.TableDescription } return tableDesc, err } // ListTables lists the DynamoDB table names for the current account. func (basics TableBasics) ListTables() ([]string, error) { var tableNames []string var output *dynamodb.ListTablesOutput var err error tablePaginator := dynamodb.NewListTablesPaginator(basics.DynamoDbClient, &dynamodb.ListTablesInput{}) for tablePaginator.HasMorePages() { output, err = tablePaginator.NextPage(context.TODO()) if err != nil { log.Printf("Couldn't list tables. Here's why: %v\n", err) break } else { tableNames = append(tableNames, output.TableNames...) } } return tableNames, err } // AddMovie adds a movie the DynamoDB table. func (basics TableBasics) AddMovie(movie Movie) error { item, err := attributevalue.MarshalMap(movie) if err != nil { panic(err) } _, err = basics.DynamoDbClient.PutItem(context.TODO(), &dynamodb.PutItemInput{ TableName: aws.String(basics.TableName), Item: item, }) if err != nil { log.Printf("Couldn't add item to table. Here's why: %v\n", err) } return err } // UpdateMovie updates the rating and plot of a movie that already exists in the // DynamoDB table. This function uses the `expression` package to build the update // expression. func (basics TableBasics) UpdateMovie(movie Movie) (map[string]map[string]interface{}, error) { var err error var response *dynamodb.UpdateItemOutput var attributeMap map[string]map[string]interface{} update := expression.Set(expression.Name("info.rating"), expression.Value(movie.Info["rating"])) update.Set(expression.Name("info.plot"), expression.Value(movie.Info["plot"])) expr, err := expression.NewBuilder().WithUpdate(update).Build() if err != nil { log.Printf("Couldn't build expression for update. Here's why: %v\n", err) } else { response, err = basics.DynamoDbClient.UpdateItem(context.TODO(), &dynamodb.UpdateItemInput{ TableName: aws.String(basics.TableName), Key: movie.GetKey(), ExpressionAttributeNames: expr.Names(), ExpressionAttributeValues: expr.Values(), UpdateExpression: expr.Update(), ReturnValues: types.ReturnValueUpdatedNew, }) if err != nil { log.Printf("Couldn't update movie %v. Here's why: %v\n", movie.Title, err) } else { err = attributevalue.UnmarshalMap(response.Attributes, &attributeMap) if err != nil { log.Printf("Couldn't unmarshall update response. Here's why: %v\n", err) } } } return attributeMap, err } // AddMovieBatch adds a slice of movies to the DynamoDB table. The function sends // batches of 25 movies to DynamoDB until all movies are added or it reaches the // specified maximum. func (basics TableBasics) AddMovieBatch(movies []Movie, maxMovies int) (int, error) { var err error var item map[string]types.AttributeValue written := 0 batchSize := 25 // DynamoDB allows a maximum batch size of 25 items. start := 0 end := start + batchSize for start < maxMovies && start < len(movies) { var writeReqs []types.WriteRequest if end > len(movies) { end = len(movies) } for _, movie := range movies[start:end] { item, err = attributevalue.MarshalMap(movie) if err != nil { log.Printf("Couldn't marshal movie %v for batch writing. Here's why: %v\n", movie.Title, err) } else { writeReqs = append( writeReqs, types.WriteRequest{PutRequest: &types.PutRequest{Item: item}}, ) } } _, err = basics.DynamoDbClient.BatchWriteItem(context.TODO(), &dynamodb.BatchWriteItemInput{ RequestItems: map[string][]types.WriteRequest{basics.TableName: writeReqs}}) if err != nil { log.Printf("Couldn't add a batch of movies to %v. Here's why: %v\n", basics.TableName, err) } else { written += len(writeReqs) } start = end end += batchSize } return written, err } // GetMovie gets movie data from the DynamoDB table by using the primary composite key // made of title and year. func (basics TableBasics) GetMovie(title string, year int) (Movie, error) { movie := Movie{Title: title, Year: year} response, err := basics.DynamoDbClient.GetItem(context.TODO(), &dynamodb.GetItemInput{ Key: movie.GetKey(), TableName: aws.String(basics.TableName), }) if err != nil { log.Printf("Couldn't get info about %v. Here's why: %v\n", title, err) } else { err = attributevalue.UnmarshalMap(response.Item, &movie) if err != nil { log.Printf("Couldn't unmarshal response. Here's why: %v\n", err) } } return movie, err } // Query gets all movies in the DynamoDB table that were released in the specified year. // The function uses the `expression` package to build the key condition expression // that is used in the query. func (basics TableBasics) Query(releaseYear int) ([]Movie, error) { var err error var response *dynamodb.QueryOutput var movies []Movie keyEx := expression.Key("year").Equal(expression.Value(releaseYear)) expr, err := expression.NewBuilder().WithKeyCondition(keyEx).Build() if err != nil { log.Printf("Couldn't build expression for query. Here's why: %v\n", err) } else { queryPaginator := dynamodb.NewQueryPaginator(basics.DynamoDbClient, &dynamodb.QueryInput{ TableName: aws.String(basics.TableName), ExpressionAttributeNames: expr.Names(), ExpressionAttributeValues: expr.Values(), KeyConditionExpression: expr.KeyCondition(), }) for queryPaginator.HasMorePages() { response, err = queryPaginator.NextPage(context.TODO()) if err != nil { log.Printf("Couldn't query for movies released in %v. Here's why: %v\n", releaseYear, err) break } else { var moviePage []Movie err = attributevalue.UnmarshalListOfMaps(response.Items, &moviePage) if err != nil { log.Printf("Couldn't unmarshal query response. Here's why: %v\n", err) break } else { movies = append(movies, moviePage...) } } } } return movies, err } // Scan gets all movies in the DynamoDB table that were released in a range of years // and projects them to return a reduced set of fields. // The function uses the `expression` package to build the filter and projection // expressions. func (basics TableBasics) Scan(startYear int, endYear int) ([]Movie, error) { var movies []Movie var err error var response *dynamodb.ScanOutput filtEx := expression.Name("year").Between(expression.Value(startYear), expression.Value(endYear)) projEx := expression.NamesList( expression.Name("year"), expression.Name("title"), expression.Name("info.rating")) expr, err := expression.NewBuilder().WithFilter(filtEx).WithProjection(projEx).Build() if err != nil { log.Printf("Couldn't build expressions for scan. Here's why: %v\n", err) } else { scanPaginator := dynamodb.NewScanPaginator(basics.DynamoDbClient, &dynamodb.ScanInput{ TableName: aws.String(basics.TableName), ExpressionAttributeNames: expr.Names(), ExpressionAttributeValues: expr.Values(), FilterExpression: expr.Filter(), ProjectionExpression: expr.Projection(), }) for scanPaginator.HasMorePages() { response, err = scanPaginator.NextPage(context.TODO()) if err != nil { log.Printf("Couldn't scan for movies released between %v and %v. Here's why: %v\n", startYear, endYear, err) break } else { var moviePage []Movie err = attributevalue.UnmarshalListOfMaps(response.Items, &moviePage) if err != nil { log.Printf("Couldn't unmarshal query response. Here's why: %v\n", err) break } else { movies = append(movies, moviePage...) } } } } return movies, err } // DeleteMovie removes a movie from the DynamoDB table. func (basics TableBasics) DeleteMovie(movie Movie) error { _, err := basics.DynamoDbClient.DeleteItem(context.TODO(), &dynamodb.DeleteItemInput{ TableName: aws.String(basics.TableName), Key: movie.GetKey(), }) if err != nil { log.Printf("Couldn't delete %v from the table. Here's why: %v\n", movie.Title, err) } return err } // DeleteTable deletes the DynamoDB table and all of its data. func (basics TableBasics) DeleteTable() error { _, err := basics.DynamoDbClient.DeleteTable(context.TODO(), &dynamodb.DeleteTableInput{ TableName: aws.String(basics.TableName)}) if err != nil { log.Printf("Couldn't delete table %v. Here's why: %v\n", basics.TableName, err) } return err }

次のコードサンプルは、以下の操作方法を示しています。

  • 複数の SELECT ステートメントを実行して、項目のバッチを取得する。

  • 複数の INSERT ステートメントを実行して、項目のバッチを追加する。

  • 複数の UPDATE ステートメントを実行して、項目のバッチを更新する。

  • 複数の DELETE ステートメントを実行して、項目のバッチを削除する。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

テーブルを作成し、PartiQL クエリのバッチを実行するシナリオを実行します。

// RunPartiQLBatchScenario shows you how to use the AWS SDK for Go // to run batches of PartiQL statements to query a table that stores data about movies. // // - Use batches of PartiQL statements to add, get, update, and delete data for // individual movies. // // This example creates an Amazon DynamoDB service client from the specified sdkConfig so that // you can replace it with a mocked or stubbed config for unit testing. // // This example creates and deletes a DynamoDB table to use during the scenario. func RunPartiQLBatchScenario(sdkConfig aws.Config, tableName string) { defer func() { if r := recover(); r != nil { fmt.Printf("Something went wrong with the demo.") } }() log.Println(strings.Repeat("-", 88)) log.Println("Welcome to the Amazon DynamoDB PartiQL batch demo.") log.Println(strings.Repeat("-", 88)) tableBasics := actions.TableBasics{ DynamoDbClient: dynamodb.NewFromConfig(sdkConfig), TableName: tableName, } runner := actions.PartiQLRunner{ DynamoDbClient: dynamodb.NewFromConfig(sdkConfig), TableName: tableName, } exists, err := tableBasics.TableExists() if err != nil { panic(err) } if !exists { log.Printf("Creating table %v...\n", tableName) _, err = tableBasics.CreateMovieTable() if err != nil { panic(err) } else { log.Printf("Created table %v.\n", tableName) } } else { log.Printf("Table %v already exists.\n", tableName) } log.Println(strings.Repeat("-", 88)) currentYear, _, _ := time.Now().Date() customMovies := []actions.Movie{{ Title: "House PartiQL", Year: currentYear - 5, Info: map[string]interface{}{ "plot": "Wacky high jinks result from querying a mysterious database.", "rating": 8.5}}, { Title: "House PartiQL 2", Year: currentYear - 3, Info: map[string]interface{}{ "plot": "Moderate high jinks result from querying another mysterious database.", "rating": 6.5}}, { Title: "House PartiQL 3", Year: currentYear - 1, Info: map[string]interface{}{ "plot": "Tepid high jinks result from querying yet another mysterious database.", "rating": 2.5}, }, } log.Printf("Inserting a batch of movies into table '%v'.\n", tableName) err = runner.AddMovieBatch(customMovies) if err == nil { log.Printf("Added %v movies to the table.\n", len(customMovies)) } log.Println(strings.Repeat("-", 88)) log.Println("Getting data for a batch of movies.") movies, err := runner.GetMovieBatch(customMovies) if err == nil { for _, movie := range movies { log.Println(movie) } } log.Println(strings.Repeat("-", 88)) newRatings := []float64{7.7, 4.4, 1.1} log.Println("Updating a batch of movies with new ratings.") err = runner.UpdateMovieBatch(customMovies, newRatings) if err == nil { log.Printf("Updated %v movies with new ratings.\n", len(customMovies)) } log.Println(strings.Repeat("-", 88)) log.Println("Getting projected data from the table to verify our update.") log.Println("Using a page size of 2 to demonstrate paging.") projections, err := runner.GetAllMovies(2) if err == nil { log.Println("All movies:") for _, projection := range projections { log.Println(projection) } } log.Println(strings.Repeat("-", 88)) log.Println("Deleting a batch of movies.") err = runner.DeleteMovieBatch(customMovies) if err == nil { log.Printf("Deleted %v movies.\n", len(customMovies)) } err = tableBasics.DeleteTable() if err == nil { log.Printf("Deleted table %v.\n", tableBasics.TableName) } log.Println(strings.Repeat("-", 88)) log.Println("Thanks for watching!") log.Println(strings.Repeat("-", 88)) }

この例で使用している Movie struct を定義します。

// Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }

PartiQL ステートメントを実行する struct およびメソッドを作成します。

// PartiQLRunner encapsulates the Amazon DynamoDB service actions used in the // PartiQL examples. It contains a DynamoDB service client that is used to act on the // specified table. type PartiQLRunner struct { DynamoDbClient *dynamodb.Client TableName string } // AddMovieBatch runs a batch of PartiQL INSERT statements to add multiple movies to the // DynamoDB table. func (runner PartiQLRunner) AddMovieBatch(movies []Movie) error { statementRequests := make([]types.BatchStatementRequest, len(movies)) for index, movie := range movies { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year, movie.Info}) if err != nil { panic(err) } statementRequests[index] = types.BatchStatementRequest{ Statement: aws.String(fmt.Sprintf( "INSERT INTO \"%v\" VALUE {'title': ?, 'year': ?, 'info': ?}", runner.TableName)), Parameters: params, } } _, err := runner.DynamoDbClient.BatchExecuteStatement(context.TODO(), &dynamodb.BatchExecuteStatementInput{ Statements: statementRequests, }) if err != nil { log.Printf("Couldn't insert a batch of items with PartiQL. Here's why: %v\n", err) } return err } // GetMovieBatch runs a batch of PartiQL SELECT statements to get multiple movies from // the DynamoDB table by title and year. func (runner PartiQLRunner) GetMovieBatch(movies []Movie) ([]Movie, error) { statementRequests := make([]types.BatchStatementRequest, len(movies)) for index, movie := range movies { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year}) if err != nil { panic(err) } statementRequests[index] = types.BatchStatementRequest{ Statement: aws.String( fmt.Sprintf("SELECT * FROM \"%v\" WHERE title=? AND year=?", runner.TableName)), Parameters: params, } } output, err := runner.DynamoDbClient.BatchExecuteStatement(context.TODO(), &dynamodb.BatchExecuteStatementInput{ Statements: statementRequests, }) var outMovies []Movie if err != nil { log.Printf("Couldn't get a batch of items with PartiQL. Here's why: %v\n", err) } else { for _, response := range output.Responses { var movie Movie err = attributevalue.UnmarshalMap(response.Item, &movie) if err != nil { log.Printf("Couldn't unmarshal response. Here's why: %v\n", err) } else { outMovies = append(outMovies, movie) } } } return outMovies, err } // GetAllMovies runs a PartiQL SELECT statement to get all movies from the DynamoDB table. // pageSize is not typically required and is used to show how to paginate the results. // The results are projected to return only the title and rating of each movie. func (runner PartiQLRunner) GetAllMovies(pageSize int32) ([]map[string]interface{}, error) { var output []map[string]interface{} var response *dynamodb.ExecuteStatementOutput var err error var nextToken *string for moreData := true; moreData; { response, err = runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("SELECT title, info.rating FROM \"%v\"", runner.TableName)), Limit: aws.Int32(pageSize), NextToken: nextToken, }) if err != nil { log.Printf("Couldn't get movies. Here's why: %v\n", err) moreData = false } else { var pageOutput []map[string]interface{} err = attributevalue.UnmarshalListOfMaps(response.Items, &pageOutput) if err != nil { log.Printf("Couldn't unmarshal response. Here's why: %v\n", err) } else { log.Printf("Got a page of length %v.\n", len(response.Items)) output = append(output, pageOutput...) } nextToken = response.NextToken moreData = nextToken != nil } } return output, err } // UpdateMovieBatch runs a batch of PartiQL UPDATE statements to update the rating of // multiple movies that already exist in the DynamoDB table. func (runner PartiQLRunner) UpdateMovieBatch(movies []Movie, ratings []float64) error { statementRequests := make([]types.BatchStatementRequest, len(movies)) for index, movie := range movies { params, err := attributevalue.MarshalList([]interface{}{ratings[index], movie.Title, movie.Year}) if err != nil { panic(err) } statementRequests[index] = types.BatchStatementRequest{ Statement: aws.String( fmt.Sprintf("UPDATE \"%v\" SET info.rating=? WHERE title=? AND year=?", runner.TableName)), Parameters: params, } } _, err := runner.DynamoDbClient.BatchExecuteStatement(context.TODO(), &dynamodb.BatchExecuteStatementInput{ Statements: statementRequests, }) if err != nil { log.Printf("Couldn't update the batch of movies. Here's why: %v\n", err) } return err } // DeleteMovieBatch runs a batch of PartiQL DELETE statements to remove multiple movies // from the DynamoDB table. func (runner PartiQLRunner) DeleteMovieBatch(movies []Movie) error { statementRequests := make([]types.BatchStatementRequest, len(movies)) for index, movie := range movies { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year}) if err != nil { panic(err) } statementRequests[index] = types.BatchStatementRequest{ Statement: aws.String( fmt.Sprintf("DELETE FROM \"%v\" WHERE title=? AND year=?", runner.TableName)), Parameters: params, } } _, err := runner.DynamoDbClient.BatchExecuteStatement(context.TODO(), &dynamodb.BatchExecuteStatementInput{ Statements: statementRequests, }) if err != nil { log.Printf("Couldn't delete the batch of movies. Here's why: %v\n", err) } return err }
  • API の詳細については、「 API リファレンスBatchExecuteStatement」の「」を参照してください。 AWS SDK for Go

次のコードサンプルは、以下の操作方法を示しています。

  • SELECT ステートメントを実行して項目を取得する。

  • INSERT 文を実行して項目を追加する。

  • UPDATE ステートメントを使用して項目を更新する。

  • DELETE ステートメントを実行して項目を削除する。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。AWS コード例リポジトリ で全く同じ例を見つけて、設定と実行の方法を確認してください。

テーブルを作成し、PartiQL クエリを実行するシナリオを実行します。

// RunPartiQLSingleScenario shows you how to use the AWS SDK for Go // to use PartiQL to query a table that stores data about movies. // // * Use PartiQL statements to add, get, update, and delete data for individual movies. // // This example creates an Amazon DynamoDB service client from the specified sdkConfig so that // you can replace it with a mocked or stubbed config for unit testing. // // This example creates and deletes a DynamoDB table to use during the scenario. func RunPartiQLSingleScenario(sdkConfig aws.Config, tableName string) { defer func() { if r := recover(); r != nil { fmt.Printf("Something went wrong with the demo.") } }() log.Println(strings.Repeat("-", 88)) log.Println("Welcome to the Amazon DynamoDB PartiQL single action demo.") log.Println(strings.Repeat("-", 88)) tableBasics := actions.TableBasics{ DynamoDbClient: dynamodb.NewFromConfig(sdkConfig), TableName: tableName, } runner := actions.PartiQLRunner{ DynamoDbClient: dynamodb.NewFromConfig(sdkConfig), TableName: tableName, } exists, err := tableBasics.TableExists() if err != nil { panic(err) } if !exists { log.Printf("Creating table %v...\n", tableName) _, err = tableBasics.CreateMovieTable() if err != nil { panic(err) } else { log.Printf("Created table %v.\n", tableName) } } else { log.Printf("Table %v already exists.\n", tableName) } log.Println(strings.Repeat("-", 88)) currentYear, _, _ := time.Now().Date() customMovie := actions.Movie{ Title: "24 Hour PartiQL People", Year: currentYear, Info: map[string]interface{}{ "plot": "A group of data developers discover a new query language they can't stop using.", "rating": 9.9, }, } log.Printf("Inserting movie '%v' released in %v.", customMovie.Title, customMovie.Year) err = runner.AddMovie(customMovie) if err == nil { log.Printf("Added %v to the movie table.\n", customMovie.Title) } log.Println(strings.Repeat("-", 88)) log.Printf("Getting data for movie '%v' released in %v.", customMovie.Title, customMovie.Year) movie, err := runner.GetMovie(customMovie.Title, customMovie.Year) if err == nil { log.Println(movie) } log.Println(strings.Repeat("-", 88)) newRating := 6.6 log.Printf("Updating movie '%v' with a rating of %v.", customMovie.Title, newRating) err = runner.UpdateMovie(customMovie, newRating) if err == nil { log.Printf("Updated %v with a new rating.\n", customMovie.Title) } log.Println(strings.Repeat("-", 88)) log.Printf("Getting data again to verify the update.") movie, err = runner.GetMovie(customMovie.Title, customMovie.Year) if err == nil { log.Println(movie) } log.Println(strings.Repeat("-", 88)) log.Printf("Deleting movie '%v'.\n", customMovie.Title) err = runner.DeleteMovie(customMovie) if err == nil { log.Printf("Deleted %v.\n", customMovie.Title) } err = tableBasics.DeleteTable() if err == nil { log.Printf("Deleted table %v.\n", tableBasics.TableName) } log.Println(strings.Repeat("-", 88)) log.Println("Thanks for watching!") log.Println(strings.Repeat("-", 88)) }

この例で使用している Movie struct を定義します。

// Movie encapsulates data about a movie. Title and Year are the composite primary key // of the movie in Amazon DynamoDB. Title is the sort key, Year is the partition key, // and Info is additional data. type Movie struct { Title string `dynamodbav:"title"` Year int `dynamodbav:"year"` Info map[string]interface{} `dynamodbav:"info"` } // GetKey returns the composite primary key of the movie in a format that can be // sent to DynamoDB. func (movie Movie) GetKey() map[string]types.AttributeValue { title, err := attributevalue.Marshal(movie.Title) if err != nil { panic(err) } year, err := attributevalue.Marshal(movie.Year) if err != nil { panic(err) } return map[string]types.AttributeValue{"title": title, "year": year} } // String returns the title, year, rating, and plot of a movie, formatted for the example. func (movie Movie) String() string { return fmt.Sprintf("%v\n\tReleased: %v\n\tRating: %v\n\tPlot: %v\n", movie.Title, movie.Year, movie.Info["rating"], movie.Info["plot"]) }

PartiQL ステートメントを実行する struct およびメソッドを作成します。

// PartiQLRunner encapsulates the Amazon DynamoDB service actions used in the // PartiQL examples. It contains a DynamoDB service client that is used to act on the // specified table. type PartiQLRunner struct { DynamoDbClient *dynamodb.Client TableName string } // AddMovie runs a PartiQL INSERT statement to add a movie to the DynamoDB table. func (runner PartiQLRunner) AddMovie(movie Movie) error { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year, movie.Info}) if err != nil { panic(err) } _, err = runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("INSERT INTO \"%v\" VALUE {'title': ?, 'year': ?, 'info': ?}", runner.TableName)), Parameters: params, }) if err != nil { log.Printf("Couldn't insert an item with PartiQL. Here's why: %v\n", err) } return err } // GetMovie runs a PartiQL SELECT statement to get a movie from the DynamoDB table by // title and year. func (runner PartiQLRunner) GetMovie(title string, year int) (Movie, error) { var movie Movie params, err := attributevalue.MarshalList([]interface{}{title, year}) if err != nil { panic(err) } response, err := runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("SELECT * FROM \"%v\" WHERE title=? AND year=?", runner.TableName)), Parameters: params, }) if err != nil { log.Printf("Couldn't get info about %v. Here's why: %v\n", title, err) } else { err = attributevalue.UnmarshalMap(response.Items[0], &movie) if err != nil { log.Printf("Couldn't unmarshal response. Here's why: %v\n", err) } } return movie, err } // UpdateMovie runs a PartiQL UPDATE statement to update the rating of a movie that // already exists in the DynamoDB table. func (runner PartiQLRunner) UpdateMovie(movie Movie, rating float64) error { params, err := attributevalue.MarshalList([]interface{}{rating, movie.Title, movie.Year}) if err != nil { panic(err) } _, err = runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("UPDATE \"%v\" SET info.rating=? WHERE title=? AND year=?", runner.TableName)), Parameters: params, }) if err != nil { log.Printf("Couldn't update movie %v. Here's why: %v\n", movie.Title, err) } return err } // DeleteMovie runs a PartiQL DELETE statement to remove a movie from the DynamoDB table. func (runner PartiQLRunner) DeleteMovie(movie Movie) error { params, err := attributevalue.MarshalList([]interface{}{movie.Title, movie.Year}) if err != nil { panic(err) } _, err = runner.DynamoDbClient.ExecuteStatement(context.TODO(), &dynamodb.ExecuteStatementInput{ Statement: aws.String( fmt.Sprintf("DELETE FROM \"%v\" WHERE title=? AND year=?", runner.TableName)), Parameters: params, }) if err != nil { log.Printf("Couldn't delete %v from the table. Here's why: %v\n", movie.Title, err) } return err }
  • API の詳細については、「 API リファレンスExecuteStatement」の「」を参照してください。 AWS SDK for Go

サーバーレスサンプル

次のコード例は、DynamoDB ストリームからレコードを受信することによってトリガーされるイベントを受信する Lambda 関数を実装する方法を示しています。関数は DynamoDB ペイロードを取得し、レコードの内容をログ記録します。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。サーバーレスサンプルリポジトリで完全な例を検索し、設定および実行の方法を確認してください。

Go を使用して Lambda で DynamoDB イベントの消費。

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. // SPDX-License-Identifier: Apache-2.0 package main import ( "context" "github.com/aws/aws-lambda-go/lambda" "github.com/aws/aws-lambda-go/events" "fmt" ) func HandleRequest(ctx context.Context, event events.DynamoDBEvent) (*string, error) { if len(event.Records) == 0 { return nil, fmt.Errorf("received empty event") } for _, record := range event.Records { LogDynamoDBRecord(record) } message := fmt.Sprintf("Records processed: %d", len(event.Records)) return &message, nil } func main() { lambda.Start(HandleRequest) } func LogDynamoDBRecord(record events.DynamoDBEventRecord){ fmt.Println(record.EventID) fmt.Println(record.EventName) fmt.Printf("%+v\n", record.Change) }

次のコード例は、DynamoDB ストリームからイベントを受信する Lambda 関数の部分的なバッチレスポンスを実装する方法を示しています。この関数は、レスポンスとしてバッチアイテムの失敗を報告し、対象のメッセージを後で再試行するよう Lambda に伝えます。

SDK for Go V2
注記

の詳細については、「」を参照してください GitHub。サーバーレスサンプルリポジトリで完全な例を検索し、設定および実行の方法を確認してください。

Go を使用して Lambda で DynamoDB のバッチアイテム失敗のレポート。

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. // SPDX-License-Identifier: Apache-2.0 package main import ( "context" "github.com/aws/aws-lambda-go/events" "github.com/aws/aws-lambda-go/lambda" ) type BatchItemFailure struct { ItemIdentifier string `json:"ItemIdentifier"` } type BatchResult struct { BatchItemFailures []BatchItemFailure `json:"BatchItemFailures"` } func HandleRequest(ctx context.Context, event events.DynamoDBEvent) (*BatchResult, error) { var batchItemFailures []BatchItemFailure curRecordSequenceNumber := "" for _, record := range event.Records { // Process your record curRecordSequenceNumber = record.Change.SequenceNumber } if curRecordSequenceNumber != "" { batchItemFailures = append(batchItemFailures, BatchItemFailure{ItemIdentifier: curRecordSequenceNumber}) } batchResult := BatchResult{ BatchItemFailures: batchItemFailures, } return &batchResult, nil } func main() { lambda.Start(HandleRequest) }