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AWS Mobile SDK
Xamarin Developer Guide

Using the DynamoDB Service Level APIs

The Dynamo Service Level APIs allow you to create, update and delete tables. You can also perform typical create, read, update, and delete (CRUD) operations on items in a table using this API.

Create a DynamoDB Client

To create a DynamoDB client:

AmazonDynamoDBClient client = new AmazonDynamoDBClient(credentials,region);

CRUD Operations

Save an Item

To save an item to a DynamoDB table:

// Create a client AmazonDynamoDBClient client = new AmazonDynamoDBClient(credentials,region); // Define item attributes Dictionary<string, AttributeValue> attributes = new Dictionary<string, AttributeValue>(); // Author is hash-key attributes["Author"] = new AttributeValue { S = "Mark Twain" }; attributes["Title"] = new AttributeValue { S = "The Adventures of Tom Sawyer" }; attributes["PageCount"] = new AttributeValue { N = "275" }; attributes["Price"] = new AttributeValue{N = "10.00"}; attributes["Id"] = new AttributeValue{N="10"}; attributes["ISBN"] = new AttributeValue{S="111-1111111"}; // Create PutItem request PutItemRequest request = new PutItemRequest { TableName = "Books", Item = attributes }; // Issue PutItem request var response = await client.PutItemAsync(request);

Retrieve an Item

To retrieve an item:

// Create a client AmazonDynamoDBClient client = new AmazonDynamoDBClient(credentials,region); Dictionary<string, AttributeValue> key = new Dictionary<string, AttributeValue> { { "Id", new AttributeValue { N = "10" } } }; // Create GetItem request GetItemRequest request = new GetItemRequest { TableName = "Books", Key = key, }; // Issue request var result = await client.GetItemAsync(request); // View response Console.WriteLine("Item:"); Dictionary<string, AttributeValue> item = result.Item; foreach (var keyValuePair in item) { Console.WriteLine("Author := {0}", item["Author"]); Console.WriteLine("Title := {0}", item["Title"]); Console.WriteLine("Price:= {0}", item["Price"]); Console.WriteLine("PageCount := {0}", item["PageCount"]); }

Update an Item

To update an item:

// Create a client AmazonDynamoDBClient client = new AmazonDynamoDBClient(credentials,region); Dictionary<string, AttributeValue> key = new Dictionary<string, AttributeValue> { { "Id", new AttributeValue { N = "10" } } }; // Define attribute updates Dictionary<string, AttributeValueUpdate> updates = new Dictionary<string, AttributeValueUpdate>(); // Add a new string to the item's Genres SS attribute updates["Genres"] = new AttributeValueUpdate() { Action = AttributeAction.ADD, Value = new AttributeValue { SS = new List<string> { "Bildungsroman" } } }; // Create UpdateItem request UpdateItemRequest request = new UpdateItemRequest { TableName = "Books", Key = key, AttributeUpdates = updates }; // Issue request var response = await client.UpdateItemAsync(request);

Delete an Item

To delete an item:

// Create a client AmazonDynamoDBClient client = new AmazonDynamoDBClient(credentials,region); Dictionary<string, AttributeValue> key = new Dictionary<string, AttributeValue> { { "Id", new AttributeValue { N = "10" } } }; // Create DeleteItem request DeleteItemRequest request = new DeleteItemRequest { TableName = "Books", Key = key }; // Issue request var response = await client.DeleteItemAsync(request);

Query and Scan

To query and retrieve all books whose author is "Mark Twain":

public void Query(AWSCredentials credentials, RegionEndpoint region) { using(var client = new AmazonDynamoDBClient(credentials, region)) { var queryResponse = await client.QueryAsync(new QueryRequest() { TableName = "Books", IndexName = "Author-Title-index", KeyConditionExpression = "Author = :v_Id", ExpressionAttributeValues = new Dictionary < string, AttributeValue > { { ":v_Id", new AttributeValue { S = "Mark Twain" } } } }); queryResponse.Items.ForEach((i) = > { Console.WriteLine(i["Title"].S); }); } }

The scan example code below returns all books in our table:

public void Scan(AWSCredentials credentials, RegionEndpoint region) { using(var client = new AmazonDynamoDBClient(credentials, region)) { var queryResponse = client.Scan(new ScanRequest() { TableName = "Books" }); queryResponse.Items.ForEach((i) = > { Console.WriteLine(i["Title"].S); }); } }