BatchPutItem

The BatchPutItem request mapping document lets you tell the AWS AppSync DynamoDB resolver to make a BatchWriteItem request to DynamoDB to put multiple items, potentially across multiple tables. For this request template, you must specify the following:

• The table names where to put the items in

• The full items to put in each table

The DynamoDB BatchWriteItem limits apply and no condition expression can be provided.

The BatchPutItem mapping document has the following structure:

{
    "version" : "2018-05-29",
    "operation" : "BatchPutItem",
    "tables" : {
        "table1": [
        ## Item to put
        {
             "foo" : ... typed value,
             "bar" : ... typed value
        },
        ## Item2 to put
        {
             "foo" : ... typed value,
             "bar" : ... typed value
        }],
        "table2": [
        ## Item3 to put
        {
             "foo" : ... typed value,
             "bar" : ... typed value
        },
        ## Item4 to put
        {
             "foo" : ... typed value,
             "bar" : ... typed value
        }],
    }
}

The fields are defined as follows:

BatchPutItem fields

BatchPutItem fields list

version

The template definition version. Only 2018-05-29 is supported. This value is required.

operation

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

tables

The DynamoDB tables to put the items in. Each table entry represents a list of DynamoDB items to insert for this specific table. At least one table must be provided. This value is required.

Things to remember:

• The fully inserted items are returned in the response, if successful.

• If an item hasn’t been inserted in the table, a null element is displayed in the data block for that table.

• The inserted items are sorted per table, based on the order in which they were provided inside the request mapping template.

• Each Put command inside a BatchPutItem is atomic, however, a batch can be partially processed. If a batch is partially processed due to an error, the unprocessed keys are returned as part of the invocation result inside the unprocessedKeys block.

• BatchPutItem is limited to 25 items.

• This operation is not supported when used with conflict detection. Using both at the same time may result in an error.

For the following example request mapping template:

{
  "version": "2018-05-29",
  "operation": "BatchPutItem",
  "tables": {
    "authors": [
        {
          "author_id": {
            "S": "a1"
          },
          "author_name": {
            "S": "a1_name"
          }
        },
    ],
    "posts": [
        {
          "author_id": {
            "S": "a1"
          },
          "post_id": {
            "S": "p2"
          },
          "post_title": {
            "S": "title"
          }
        }
    ],
  }
}

The invocation result available in $ctx.result is as follows:

{
   "data": {
     "authors": [
         null
     ],
     "posts": [
        # Was inserted
        {
          "author_id": "a1",
          "post_id": "p2",
          "post_title": "title"
        }
     ]
   },
   "unprocessedItems": {
     "authors": [
        # This item was not processed due to an error
        {
          "author_id": "a1",
          "author_name": "a1_name"
        }
      ],
     "posts": []
   }
}

The $ctx.error contains details about the error. The keys data, unprocessedItems, and each table key that was provided in the request mapping template are guaranteed to be present in the invocation result. Items that have been inserted are in the data block. Items that haven’t been processed are marked as null inside the data block and are placed inside the unprocessedItems block.

For a more complete example, follow the DynamoDB Batch tutorial with AppSync here Tutorial: DynamoDB batch resolvers.