GetItem - AWS AppSync GraphQL
GetItem fieldsExample

GetItem

The GetItem request mapping document lets you tell the AWS AppSync DynamoDB resolver to make a GetItem request to DynamoDB, and enables you to specify:

  • The key of the item in DynamoDB

  • Whether to use a consistent read or not

The GetItem mapping document has the following structure:

{
    "version" : "2017-02-28",
    "operation" : "GetItem",
    "key" : {
        "foo" : ... typed value,
        "bar" : ... typed value
    },
    "consistentRead" : true,
    "projection" : {
        ...
    }
}

The fields are defined as follows:

GetItem fields

version

The template definition version. 2017-02-28 and 2018-05-29 are currently supported. This value is required.

operation

The DynamoDB operation to perform. To perform the GetItem DynamoDB operation, this must be set to GetItem. This value is required.

key

The key of the item in DynamoDB. DynamoDB items may have a single hash key, or a hash key and sort key, depending on the table structure. For more information about how to specify a “typed value”, see Type system (request mapping). This value is required.

consistentRead

Whether or not to perform a strongly consistent read with DynamoDB. This is optional, and defaults to false.

projection

A projection that's used to specify the attributes to return from the DynamoDB operation. For more information about projections, see Projections. This field is optional.

The item returned from DynamoDB is automatically converted into GraphQL and JSON primitive types, and is available in the mapping context ($context.result).

For more information about DynamoDB type conversion, see Type system (response mapping).

For more information about response mapping templates, see Resolver mapping template overview.

Example

The following example is a mapping template for a GraphQL query getThing(foo: String!, bar: String!):

{
    "version" : "2017-02-28",
    "operation" : "GetItem",
    "key" : {
        "foo" : $util.dynamodb.toDynamoDBJson($ctx.args.foo),
        "bar" : $util.dynamodb.toDynamoDBJson($ctx.args.bar)
    },
    "consistentRead" : true
}

For more information about the DynamoDB GetItem API, see the DynamoDB API documentation.