BatchDeleteItem - AWS AppSync GraphQL
BatchDeleteItem fields

BatchDeleteItem

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

  • The table names where to delete the items from

  • The keys of the items to delete from each table

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

The BatchDeleteItem mapping document has the following structure:

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

The fields are defined as follows:

BatchDeleteItem fields

version

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

operation

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

tables

The DynamoDB tables to delete the items from. Each table is a list of DynamoDB keys representing the primary key of the items to delete. 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). At least one table must be provided. The tables value is required.

Things to remember:

  • Contrary to the DeleteItem operation, the fully deleted item isn’t returned in the response. Only the passed key is returned.

  • If an item has not been deleted from the table, a null element appears in the data block for that table.

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

  • Each Delete command inside a BatchDeleteItem 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.

  • BatchDeleteItem is limited to 25 keys.

  • 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": "BatchDeleteItem",
  "tables": {
    "authors": [
        {
          "author_id": {
            "S": "a1"
          }
        },
    ],
    "posts": [
        {
          "author_id": {
            "S": "a1"
          },
          "post_id": {
            "S": "p2"
          }
        }
    ],
  }
}

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

{
   "data": {
     "authors": [null],
     "posts": [
        # Was deleted
        {
          "author_id": "a1",
          "post_id": "p2"
        }
     ]
   },
   "unprocessedKeys": {
     "authors": [
        # This key was not processed due to an error
        {
          "author_id": "a1"
        }
      ],
     "posts": []
   }
}

The $ctx.error contains details about the error. The keys data, unprocessedKeys, 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 deleted are present in the data block. Items that haven’t been processed are marked as null inside the data block and are placed inside the unprocessedKeys block.

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