DynamoDB 用紅寶石的示例 SDK

下列程式碼範例說明如何透過 AWS SDK for Ruby 與 DynamoDB 搭配使用來執行動作和實作常見案例。

基本概念是程式碼範例，會示範如何在服務中執行基本作業。

Actions 是大型程式的程式碼摘錄，必須在內容中執行。雖然動作會顯示如何呼叫個別服務函數，但您可以在其相關案例中查看內容中的動作。

案例是程式碼範例，向您展示如何透過呼叫服務中的多個函數或與其他函式結合來完成特定工作 AWS 服務。

每個範例都包含完整原始程式碼的連結，您可以在其中找到如何在內容中設定和執行程式碼的指示。

開始使用

下列程式碼範例示範如何開始使用 DynamoDB。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。



require 'aws-sdk-dynamodb'
require 'logger'

# DynamoDBManager is a class responsible for managing DynamoDB operations
# such as listing all tables in the current AWS account.
class DynamoDBManager
  def initialize(client)
    @client = client
    @logger = Logger.new($stdout)
  end

  # Lists and prints all DynamoDB tables in the current AWS account.
  def list_tables
    @logger.info('Here are the DynamoDB tables in your account:')

    paginator = @client.list_tables(limit: 10)
    table_names = []

    paginator.each_page do |page|
      page.table_names.each do |table_name|
        @logger.info("- #{table_name}")
        table_names << table_name
      end
    end

    if table_names.empty?
      @logger.info("You don't have any DynamoDB tables in your account.")
    else
      @logger.info("\nFound #{table_names.length} tables.")
    end
  end
end

if $PROGRAM_NAME == __FILE__
  dynamodb_client = Aws::DynamoDB::Client.new
  manager = DynamoDBManager.new(dynamodb_client)
  manager.list_tables
end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考ListTables中的。

基本概念

以下程式碼範例顯示做法：

建立可存放電影資料的資料表。
放入、取得和更新資料表中的單個電影。
從範例JSON檔案將影片資料寫入資料表。
查詢特定年份發表的電影。
掃描某個年份範圍內發表的電影。
從資料表刪除電影，然後刪除資料表。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。

建立封裝 DynamoDB 資料表的類別。


  # Creates an Amazon DynamoDB table that can be used to store movie data.
  # The table uses the release year of the movie as the partition key and the
  # title as the sort key.
  #
  # @param table_name [String] The name of the table to create.
  # @return [Aws::DynamoDB::Table] The newly created table.
  def create_table(table_name)
    @table = @dynamo_resource.create_table(
      table_name: table_name,
      key_schema: [
        {attribute_name: "year", key_type: "HASH"},  # Partition key
        {attribute_name: "title", key_type: "RANGE"}  # Sort key
      ],
      attribute_definitions: [
        {attribute_name: "year", attribute_type: "N"},
        {attribute_name: "title", attribute_type: "S"}
      ],
      provisioned_throughput: {read_capacity_units: 10, write_capacity_units: 10})
    @dynamo_resource.client.wait_until(:table_exists, table_name: table_name)
    @table
  rescue Aws::DynamoDB::Errors::ServiceError => e
    @logger.error("Failed create table #{table_name}:\n#{e.code}: #{e.message}")
    raise
  end

創建一個輔助函數以下載並提取示例JSON文件。


  # Gets sample movie data, either from a local file or by first downloading it from
  # the Amazon DynamoDB Developer Guide.
  #
  # @param movie_file_name [String] The local file name where the movie data is stored in JSON format.
  # @return [Hash] The movie data as a Hash.
  def fetch_movie_data(movie_file_name)
    if !File.file?(movie_file_name)
      @logger.debug("Downloading #{movie_file_name}...")
      movie_content = URI.open(
        "https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/samples/moviedata.zip"
      )
      movie_json = ""
      Zip::File.open_buffer(movie_content) do |zip|
        zip.each do |entry|
          movie_json = entry.get_input_stream.read
        end
      end
    else
      movie_json = File.read(movie_file_name)
    end
    movie_data = JSON.parse(movie_json)
    # The sample file lists over 4000 movies. This returns only the first 250.
    movie_data.slice(0, 250)
  rescue StandardError => e
    puts("Failure downloading movie data:\n#{e}")
    raise
  end

執行互動式案例以建立資料表並對其執行動作。


  table_name = "doc-example-table-movies-#{rand(10**4)}"
  scaffold = Scaffold.new(table_name)
  dynamodb_wrapper = DynamoDBBasics.new(table_name)

  new_step(1, "Create a new DynamoDB table if none already exists.")
  unless scaffold.exists?(table_name)
    puts("\nNo such table: #{table_name}. Creating it...")
    scaffold.create_table(table_name)
    print "Done!\n".green
  end

  new_step(2, "Add a new record to the DynamoDB table.")
  my_movie = {}
  my_movie[:title] = CLI::UI::Prompt.ask("Enter the title of a movie to add to the table. E.g. The Matrix")
  my_movie[:year] = CLI::UI::Prompt.ask("What year was it released? E.g. 1989").to_i
  my_movie[:rating] = CLI::UI::Prompt.ask("On a scale of 1 - 10, how do you rate it? E.g. 7").to_i
  my_movie[:plot] = CLI::UI::Prompt.ask("Enter a brief summary of the plot. E.g. A man awakens to a new reality.")
  dynamodb_wrapper.add_item(my_movie)
  puts("\nNew record added:")
  puts JSON.pretty_generate(my_movie).green
  print "Done!\n".green

  new_step(3, "Update a record in the DynamoDB table.")
  my_movie[:rating] = CLI::UI::Prompt.ask("Let's update the movie you added with a new rating, e.g. 3:").to_i
  response = dynamodb_wrapper.update_item(my_movie)
  puts("Updated '#{my_movie[:title]}' with new attributes:")
  puts JSON.pretty_generate(response).green
  print "Done!\n".green

  new_step(4, "Get a record from the DynamoDB table.")
  puts("Searching for #{my_movie[:title]} (#{my_movie[:year]})...")
  response = dynamodb_wrapper.get_item(my_movie[:title], my_movie[:year])
  puts JSON.pretty_generate(response).green
  print "Done!\n".green

  new_step(5, "Write a batch of items into the DynamoDB table.")
  download_file = "moviedata.json"
  puts("Downloading movie database to #{download_file}...")
  movie_data = scaffold.fetch_movie_data(download_file)
  puts("Writing movie data from #{download_file} into your table...")
  scaffold.write_batch(movie_data)
  puts("Records added: #{movie_data.length}.")
  print "Done!\n".green

  new_step(5, "Query for a batch of items by key.")
  loop do
    release_year = CLI::UI::Prompt.ask("Enter a year between 1972 and 2018, e.g. 1999:").to_i
    results = dynamodb_wrapper.query_items(release_year)
    if results.any?
      puts("There were #{results.length} movies released in #{release_year}:")
      results.each do |movie|
        print "\t #{movie["title"]}".green
      end
      break
    else
      continue = CLI::UI::Prompt.ask("Found no movies released in #{release_year}! Try another year? (y/n)")
      break if !continue.eql?("y")
    end
  end
  print "\nDone!\n".green

  new_step(6, "Scan for a batch of items using a filter expression.")
  years = {}
  years[:start] = CLI::UI::Prompt.ask("Enter a starting year between 1972 and 2018:")
  years[:end] = CLI::UI::Prompt.ask("Enter an ending year between 1972 and 2018:")
  releases = dynamodb_wrapper.scan_items(years)
  if !releases.empty?
    puts("Found #{releases.length} movies.")
    count = Question.ask(
      "How many do you want to see? ", method(:is_int), in_range(1, releases.length))
    puts("Here are your #{count} movies:")
    releases.take(count).each do |release|
      puts("\t#{release["title"]}")
    end
  else
    puts("I don't know about any movies released between #{years[:start]} "\
         "and #{years[:end]}.")
  end
  print "\nDone!\n".green

  new_step(7, "Delete an item from the DynamoDB table.")
  answer = CLI::UI::Prompt.ask("Do you want to remove '#{my_movie[:title]}'? (y/n) ")
  if answer.eql?("y")
    dynamodb_wrapper.delete_item(my_movie[:title], my_movie[:year])
    puts("Removed '#{my_movie[:title]}' from the table.")
    print "\nDone!\n".green
  end

  new_step(8, "Delete the DynamoDB table.")
  answer = CLI::UI::Prompt.ask("Delete the table? (y/n)")
  if answer.eql?("y")
    scaffold.delete_table
    puts("Deleted #{table_name}.")
  else
    puts("Don't forget to delete the table when you're done!")
  end
  print "\nThanks for watching!\n".green
rescue Aws::Errors::ServiceError
  puts("Something went wrong with the demo.")
rescue Errno::ENOENT
  true
end

如需詳API細資訊，請參閱「AWS SDK for Ruby API參考」中的下列主題。

動作

下列程式碼範例會示範如何使用BatchExecuteStatement。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。

使用 PartiQL 讀取一批項目。


class DynamoDBPartiQLBatch

  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamodb = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamodb.table(table_name)
  end

  # Selects a batch of items from a table using PartiQL
  #
  # @param batch_titles [Array] Collection of movie titles
  # @return [Aws::DynamoDB::Types::BatchExecuteStatementOutput]
  def batch_execute_select(batch_titles)
    request_items = batch_titles.map do |title, year|
      {
        statement: "SELECT * FROM \"#{@table.name}\" WHERE title=? and year=?",
        parameters: [title, year]
      }
    end
    @dynamodb.client.batch_execute_statement({statements: request_items})
  end

使用 PartiQL 刪除一批項目。


class DynamoDBPartiQLBatch

  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamodb = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamodb.table(table_name)
  end

  # Deletes a batch of items from a table using PartiQL
  #
  # @param batch_titles [Array] Collection of movie titles
  # @return [Aws::DynamoDB::Types::BatchExecuteStatementOutput]
  def batch_execute_write(batch_titles)
    request_items = batch_titles.map do |title, year|
      {
        statement: "DELETE FROM \"#{@table.name}\" WHERE title=? and year=?",
        parameters: [title, year]
      }
    end
    @dynamodb.client.batch_execute_statement({statements: request_items})
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考BatchExecuteStatement中的。

下列程式碼範例會示範如何使用BatchWriteItem。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


class DynamoDBBasics
  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamo_resource.table(table_name)
  end

  # Fills an Amazon DynamoDB table with the specified data. Items are sent in
  # batches of 25 until all items are written.
  #
  # @param movies [Enumerable] The data to put in the table. Each item must contain at least
  #                            the keys required by the schema that was specified when the
  #                            table was created.
  def write_batch(movies)
    index = 0
    slice_size = 25
    while index < movies.length
      movie_items = []
      movies[index, slice_size].each do |movie|
        movie_items.append({put_request: { item: movie }})
      end
      @dynamo_resource.client.batch_write_item({request_items: { @table.name => movie_items }})
      index += slice_size
    end
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts(
      "Couldn't load data into table #{@table.name}. Here's why:")
    puts("\t#{e.code}: #{e.message}")
    raise
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考BatchWriteItem中的。

下列程式碼範例會示範如何使用CreateTable。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


# Encapsulates an Amazon DynamoDB table of movie data.
class Scaffold
  attr_reader :dynamo_resource
  attr_reader :table_name
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table_name = table_name
    @table = nil
    @logger = Logger.new($stdout)
    @logger.level = Logger::DEBUG
  end

  # Creates an Amazon DynamoDB table that can be used to store movie data.
  # The table uses the release year of the movie as the partition key and the
  # title as the sort key.
  #
  # @param table_name [String] The name of the table to create.
  # @return [Aws::DynamoDB::Table] The newly created table.
  def create_table(table_name)
    @table = @dynamo_resource.create_table(
      table_name: table_name,
      key_schema: [
        {attribute_name: "year", key_type: "HASH"},  # Partition key
        {attribute_name: "title", key_type: "RANGE"}  # Sort key
      ],
      attribute_definitions: [
        {attribute_name: "year", attribute_type: "N"},
        {attribute_name: "title", attribute_type: "S"}
      ],
      provisioned_throughput: {read_capacity_units: 10, write_capacity_units: 10})
    @dynamo_resource.client.wait_until(:table_exists, table_name: table_name)
    @table
  rescue Aws::DynamoDB::Errors::ServiceError => e
    @logger.error("Failed create table #{table_name}:\n#{e.code}: #{e.message}")
    raise
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考CreateTable中的。

下列程式碼範例會示範如何使用DeleteItem。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


class DynamoDBBasics
  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamo_resource.table(table_name)
  end

  # Deletes a movie from the table.
  #
  # @param title [String] The title of the movie to delete.
  # @param year [Integer] The release year of the movie to delete.
  def delete_item(title, year)
    @table.delete_item(key: {"year" => year, "title" => title})
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't delete movie #{title}. Here's why:")
    puts("\t#{e.code}: #{e.message}")
    raise
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考DeleteItem中的。

下列程式碼範例會示範如何使用DeleteTable。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


# Encapsulates an Amazon DynamoDB table of movie data.
class Scaffold
  attr_reader :dynamo_resource
  attr_reader :table_name
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table_name = table_name
    @table = nil
    @logger = Logger.new($stdout)
    @logger.level = Logger::DEBUG
  end

  # Deletes the table.
  def delete_table
    @table.delete
    @table = nil
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't delete table. Here's why:")
    puts("\t#{e.code}: #{e.message}")
    raise
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考DeleteTable中的。

下列程式碼範例會示範如何使用DescribeTable。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


# Encapsulates an Amazon DynamoDB table of movie data.
class Scaffold
  attr_reader :dynamo_resource
  attr_reader :table_name
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table_name = table_name
    @table = nil
    @logger = Logger.new($stdout)
    @logger.level = Logger::DEBUG
  end

  # Determines whether a table exists. As a side effect, stores the table in
  # a member variable.
  #
  # @param table_name [String] The name of the table to check.
  # @return [Boolean] True when the table exists; otherwise, False.
  def exists?(table_name)
    @dynamo_resource.client.describe_table(table_name: table_name)
    @logger.debug("Table #{table_name} exists")
  rescue Aws::DynamoDB::Errors::ResourceNotFoundException
    @logger.debug("Table #{table_name} doesn't exist")
    false
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't check for existence of #{table_name}:\n")
    puts("\t#{e.code}: #{e.message}")
    raise
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考DescribeTable中的。

下列程式碼範例會示範如何使用ExecuteStatement。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。

使用 PartiQL 選取單一項目。


class DynamoDBPartiQLSingle

  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamodb = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamodb.table(table_name)
  end

  # Gets a single record from a table using PartiQL.
  # Note: To perform more fine-grained selects,
  # use the Client.query instance method instead.
  #
  # @param title [String] The title of the movie to search.
  # @return [Aws::DynamoDB::Types::ExecuteStatementOutput]
  def select_item_by_title(title)
    request = {
      statement: "SELECT * FROM \"#{@table.name}\" WHERE title=?",
      parameters: [title]
    }
    @dynamodb.client.execute_statement(request)
  end

使用 PartiQL 更新單一項目。


class DynamoDBPartiQLSingle

  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamodb = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamodb.table(table_name)
  end

  # Updates a single record from a table using PartiQL.
  #
  # @param title [String] The title of the movie to update.
  # @param year [Integer] The year the movie was released.
  # @param rating [Float] The new rating to assign the title.
  # @return [Aws::DynamoDB::Types::ExecuteStatementOutput]
  def update_rating_by_title(title, year, rating)
    request = {
      statement: "UPDATE \"#{@table.name}\" SET info.rating=? WHERE title=? and year=?",
      parameters: [{ "N": rating }, title, year]
    }
    @dynamodb.client.execute_statement(request)
  end

使用 PartiQL 新增單一項目。


class DynamoDBPartiQLSingle

  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamodb = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamodb.table(table_name)
  end

  # Adds a single record to a table using PartiQL.
  #
  # @param title [String] The title of the movie to update.
  # @param year [Integer] The year the movie was released.
  # @param plot [String] The plot of the movie.
  # @param rating [Float] The new rating to assign the title.
  # @return [Aws::DynamoDB::Types::ExecuteStatementOutput]
  def insert_item(title, year, plot, rating)
    request = {
      statement: "INSERT INTO \"#{@table.name}\" VALUE {'title': ?, 'year': ?, 'info': ?}",
      parameters: [title, year, {'plot': plot, 'rating': rating}]
    }
    @dynamodb.client.execute_statement(request)
  end

使用 PartiQL 刪除單一項目。


class DynamoDBPartiQLSingle

  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamodb = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamodb.table(table_name)
  end

  # Deletes a single record from a table using PartiQL.
  #
  # @param title [String] The title of the movie to update.
  # @param year [Integer] The year the movie was released.
  # @return [Aws::DynamoDB::Types::ExecuteStatementOutput]
  def delete_item_by_title(title, year)
    request = {
      statement: "DELETE FROM \"#{@table.name}\" WHERE title=? and year=?",
      parameters: [title, year]
    }
    @dynamodb.client.execute_statement(request)
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考ExecuteStatement中的。

下列程式碼範例會示範如何使用GetItem。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


class DynamoDBBasics
  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamo_resource.table(table_name)
  end

  # Gets movie data from the table for a specific movie.
  #
  # @param title [String] The title of the movie.
  # @param year [Integer] The release year of the movie.
  # @return [Hash] The data about the requested movie.
  def get_item(title, year)
    @table.get_item(key: {"year" => year, "title" => title})
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't get movie #{title} (#{year}) from table #{@table.name}:\n")
    puts("\t#{e.code}: #{e.message}")
    raise
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考GetItem中的。

下列程式碼範例會示範如何使用ListTables。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。

判斷資料表是否存在。


# Encapsulates an Amazon DynamoDB table of movie data.
class Scaffold
  attr_reader :dynamo_resource
  attr_reader :table_name
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table_name = table_name
    @table = nil
    @logger = Logger.new($stdout)
    @logger.level = Logger::DEBUG
  end

  # Determines whether a table exists. As a side effect, stores the table in
  # a member variable.
  #
  # @param table_name [String] The name of the table to check.
  # @return [Boolean] True when the table exists; otherwise, False.
  def exists?(table_name)
    @dynamo_resource.client.describe_table(table_name: table_name)
    @logger.debug("Table #{table_name} exists")
  rescue Aws::DynamoDB::Errors::ResourceNotFoundException
    @logger.debug("Table #{table_name} doesn't exist")
    false
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't check for existence of #{table_name}:\n")
    puts("\t#{e.code}: #{e.message}")
    raise
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考ListTables中的。

下列程式碼範例會示範如何使用PutItem。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


class DynamoDBBasics
  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamo_resource.table(table_name)
  end

  # Adds a movie to the table.
  #
  # @param movie [Hash] The title, year, plot, and rating of the movie.
  def add_item(movie)
    @table.put_item(
      item: {
        "year" => movie[:year],
        "title" => movie[:title],
        "info" => {"plot" => movie[:plot], "rating" => movie[:rating]}})
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't add movie #{title} to table #{@table.name}. Here's why:")
    puts("\t#{e.code}: #{e.message}")
    raise
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考PutItem中的。

下列程式碼範例會示範如何使用Query。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


class DynamoDBBasics
  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamo_resource.table(table_name)
  end

  # Queries for movies that were released in the specified year.
  #
  # @param year [Integer] The year to query.
  # @return [Array] The list of movies that were released in the specified year.
  def query_items(year)
    response = @table.query(
      key_condition_expression: "#yr = :year",
      expression_attribute_names: {"#yr" => "year"},
      expression_attribute_values: {":year" => year})
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't query for movies released in #{year}. Here's why:")
    puts("\t#{e.code}: #{e.message}")
    raise
  else
    response.items
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考中的查詢。

下列程式碼範例會示範如何使用Scan。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


class DynamoDBBasics
  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamo_resource.table(table_name)
  end

  # Scans for movies that were released in a range of years.
  # Uses a projection expression to return a subset of data for each movie.
  #
  # @param year_range [Hash] The range of years to retrieve.
  # @return [Array] The list of movies released in the specified years.
  def scan_items(year_range)
    movies = []
    scan_hash = {
      filter_expression: "#yr between :start_yr and :end_yr",
      projection_expression: "#yr, title, info.rating",
      expression_attribute_names: {"#yr" => "year"},
      expression_attribute_values: {
        ":start_yr" => year_range[:start], ":end_yr" => year_range[:end]}
    }
    done = false
    start_key = nil
    until done
      scan_hash[:exclusive_start_key] = start_key unless start_key.nil?
      response = @table.scan(scan_hash)
      movies.concat(response.items) unless response.items.empty?
      start_key = response.last_evaluated_key
      done = start_key.nil?
    end
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't scan for movies. Here's why:")
    puts("\t#{e.code}: #{e.message}")
    raise
  else
    movies
  end

如需詳API細資訊，請參閱在AWS SDK for Ruby API參考中掃描。

下列程式碼範例會示範如何使用UpdateItem。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。


class DynamoDBBasics
  attr_reader :dynamo_resource
  attr_reader :table

  def initialize(table_name)
    client = Aws::DynamoDB::Client.new(region: "us-east-1")
    @dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
    @table = @dynamo_resource.table(table_name)
  end

  # Updates rating and plot data for a movie in the table.
  #
  # @param movie [Hash] The title, year, plot, rating of the movie.
  def update_item(movie)

    response = @table.update_item(
      key: {"year" => movie[:year], "title" => movie[:title]},
      update_expression: "set info.rating=:r",
      expression_attribute_values: { ":r" => movie[:rating] },
      return_values: "UPDATED_NEW")
  rescue Aws::DynamoDB::Errors::ServiceError => e
    puts("Couldn't update movie #{movie[:title]} (#{movie[:year]}) in table #{@table.name}\n")
    puts("\t#{e.code}: #{e.message}")
    raise
  else
    response.attributes
  end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考UpdateItem中的。

案例

以下程式碼範例顯示做法：

通過運行多個SELECT語句獲取一批項目。
通過運行多個INSERT語句添加一批項目。
執行多個UPDATE陳述式來更新一批項目。
執行多個DELETE陳述式以刪除批次項目。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。

執行一個情境，該情境會建立資料表並執行批次 PartiQL 查詢。


  table_name = "doc-example-table-movies-partiql-#{rand(10**4)}"
  scaffold = Scaffold.new(table_name)
  sdk = DynamoDBPartiQLBatch.new(table_name)

  new_step(1, "Create a new DynamoDB table if none already exists.")
  unless scaffold.exists?(table_name)
    puts("\nNo such table: #{table_name}. Creating it...")
    scaffold.create_table(table_name)
    print "Done!\n".green
  end

  new_step(2, "Populate DynamoDB table with movie data.")
  download_file = "moviedata.json"
  puts("Downloading movie database to #{download_file}...")
  movie_data = scaffold.fetch_movie_data(download_file)
  puts("Writing movie data from #{download_file} into your table...")
  scaffold.write_batch(movie_data)
  puts("Records added: #{movie_data.length}.")
  print "Done!\n".green

  new_step(3, "Select a batch of items from the movies table.")
  puts "Let's select some popular movies for side-by-side comparison."
  response = sdk.batch_execute_select([["Mean Girls", 2004], ["Goodfellas", 1977], ["The Prancing of the Lambs", 2005]])
  puts("Items selected: #{response['responses'].length}\n")
  print "\nDone!\n".green

  new_step(4, "Delete a batch of items from the movies table.")
  sdk.batch_execute_write([["Mean Girls", 2004], ["Goodfellas", 1977], ["The Prancing of the Lambs", 2005]])
  print "\nDone!\n".green

  new_step(5, "Delete the table.")
  if scaffold.exists?(table_name)
    scaffold.delete_table
  end
end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考BatchExecuteStatement中的。

以下程式碼範例顯示做法：

透過執行SELECT陳述式取得項目。
執行INSERT陳述式以新增項目。
執行UPDATE陳述式以更新項目。
執行DELETE陳述式以刪除項目。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在 AWS 程式碼範例儲存庫中設定和執行。

執行一個情境，該情境建立資料表並執行 PartiQL 查詢。


  table_name = "doc-example-table-movies-partiql-#{rand(10**8)}"
  scaffold = Scaffold.new(table_name)
  sdk = DynamoDBPartiQLSingle.new(table_name)

  new_step(1, "Create a new DynamoDB table if none already exists.")
  unless scaffold.exists?(table_name)
    puts("\nNo such table: #{table_name}. Creating it...")
    scaffold.create_table(table_name)
    print "Done!\n".green
  end

  new_step(2, "Populate DynamoDB table with movie data.")
  download_file = "moviedata.json"
  puts("Downloading movie database to #{download_file}...")
  movie_data = scaffold.fetch_movie_data(download_file)
  puts("Writing movie data from #{download_file} into your table...")
  scaffold.write_batch(movie_data)
  puts("Records added: #{movie_data.length}.")
  print "Done!\n".green

  new_step(3, "Select a single item from the movies table.")
  response = sdk.select_item_by_title("Star Wars")
  puts("Items selected for title 'Star Wars': #{response.items.length}\n")
  print "#{response.items.first}".yellow
  print "\n\nDone!\n".green

  new_step(4, "Update a single item from the movies table.")
  puts "Let's correct the rating on The Big Lebowski to 10.0."
  sdk.update_rating_by_title("The Big Lebowski", 1998, 10.0)
  print "\nDone!\n".green

  new_step(5, "Delete a single item from the movies table.")
  puts "Let's delete The Silence of the Lambs because it's just too scary."
  sdk.delete_item_by_title("The Silence of the Lambs", 1991)
  print "\nDone!\n".green

  new_step(6, "Insert a new item into the movies table.")
  puts "Let's create a less-scary movie called The Prancing of the Lambs."
  sdk.insert_item("The Prancing of the Lambs", 2005, "A movie about happy livestock.", 5.0)
  print "\nDone!\n".green

  new_step(7, "Delete the table.")
  if scaffold.exists?(table_name)
    scaffold.delete_table
  end
end

如需詳API細資訊，請參閱AWS SDK for Ruby API參考ExecuteStatement中的。

無伺服器範例

下列程式碼範例示範如何實作 Lambda 函數，該函數會接收透過從 DynamoDB 串流接收記錄而觸發的事件。此函數會擷取 DynamoDB 承載並記錄記錄內容。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在無伺服器範例儲存庫中設定和執行。

使用紅寶石與 Lambda 一起使用 DynamoDB 事件。



def lambda_handler(event:, context:)
    return 'received empty event' if event['Records'].empty?
  
    event['Records'].each do |record|
      log_dynamodb_record(record)
    end
  
    "Records processed: #{event['Records'].length}"
  end
  
  def log_dynamodb_record(record)
    puts record['eventID']
    puts record['eventName']
    puts "DynamoDB Record: #{JSON.generate(record['dynamodb'])}"
  end

下列程式碼範例示範如何針對接收來自 DynamoDB 串流之事件的 Lambda 函數實作部分批次回應。此函數會在回應中報告批次項目失敗，指示 Lambda 稍後重試這些訊息。

SDK對於紅寶石

注意

還有更多關於 GitHub。尋找完整範例，並了解如何在無伺服器範例儲存庫中設定和執行。

使用紅寶石使用 Lambda 報告批次項目失敗。


def lambda_handler(event:, context:)
    records = event["Records"]
    cur_record_sequence_number = ""
  
    records.each do |record|
      begin
        # Process your record
        cur_record_sequence_number = record["dynamodb"]["SequenceNumber"]
      rescue StandardError => e
        # Return failed record's sequence number
        return {"batchItemFailures" => [{"itemIdentifier" => cur_record_sequence_number}]}
      end
    end
  
    {"batchItemFailures" => []}
  end

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