# DeleteItem
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The `DeleteItem` request lets you tell the AWS AppSync DynamoDB function to make a `DeleteItem` request to DynamoDB, and enables you to specify the following:
+ The key of the item in DynamoDB
+ Conditions for the operation to succeed

The `DeleteItem` request has the following structure:

```
type DynamoDBDeleteItemRequest = {
  operation: 'DeleteItem';
  key: { [key: string]: any };
  condition?: ConditionCheckExpression;
  customPartitionKey?: string;
  populateIndexFields?: boolean;
  _version?: number;
};
```

The fields are defined as follows:

## DeleteItem fields
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### DeleteItem fields list
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** `operation` **  
The DynamoDB operation to perform. To perform the `DeleteItem` DynamoDB operation, this must be set to `DeleteItem`. 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 specifying a “typed value”, see [Type system (request mapping)](https://docs.aws.amazon.com/appsync/latest/devguide/js-resolver-reference-dynamodb.html#js-aws-appsync-resolver-reference-dynamodb-typed-values-request). This value is required.

** `condition` **  
A condition to determine if the request should succeed or not, based on the state of the object already in DynamoDB. If no condition is specified, the `DeleteItem` request deletes an item regardless of its current state. For more information about conditions, see [Condition expressions](https://docs.aws.amazon.com/appsync/latest/devguide/js-resolver-reference-dynamodb.html#js-aws-appsync-resolver-reference-dynamodb-condition-expressions). This value is optional.

** `_version` **  
A numeric value that represents the latest known version of an item. This value is optional. This field is used for *Conflict Detection* and is only supported on versioned data sources.

**`customPartitionKey`**  
When enabled, this string value modifies the format of the `ds_sk` and `ds_pk` records used by the delta sync table when versioning has been enabled (for more information, see [Conflict detection and sync](https://docs.aws.amazon.com/appsync/latest/devguide/conflict-detection-and-sync.html) in the *AWS AppSync Developer Guide*). When enabled, the processing of the `populateIndexFields` entry is also enabled. This field is optional.

**`populateIndexFields`**  
A boolean value that, when enabled **along with the `customPartitionKey`**, creates new entries for each record in the delta sync table, specifically in the `gsi_ds_pk` and `gsi_ds_sk` columns. For more information, see [Conflict detection and sync](https://docs.aws.amazon.com/appsync/latest/devguide/conflict-detection-and-sync.html) in the *AWS AppSync Developer Guide*. This field is optional. 

The item deleted from DynamoDB is automatically converted into GraphQL and JSON primitive types and is available in the context result (`context.result`).

For more information about DynamoDB type conversion, see [Type system (response mapping)](https://docs.aws.amazon.com/appsync/latest/devguide/js-resolver-reference-dynamodb.html#js-aws-appsync-resolver-reference-dynamodb-typed-values-responses).

For more information about JavaScript resolvers, see [JavaScript resolvers overview](https://docs.aws.amazon.com/appsync/latest/devguide/resolver-reference-overview-js.html).

## Example 1
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The following example is a function request handler for a GraphQL mutation `deleteItem(id: ID!)`. If an item exists with this ID, it’s deleted.

```
import { util } from '@aws-appsync/utils';
export function request(ctx) {
  return {
    operation: 'DeleteItem',
    key: util.dynamodb.toMapValues({ id: ctx.args.id }),
  };
}
```

## Example 2
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The following example is a function request handler for a GraphQL mutation `deleteItem(id: ID!, expectedVersion: Int!)`. If an item exists with this ID, it’s deleted, but only if its `version` field set to `expectedVersion`:

```
import { util } from '@aws-appsync/utils';

export function request(ctx) {
  const { id, expectedVersion } = ctx.args;
  const condition = {
    id: { attributeExists: true },
    version: { eq: expectedVersion },
  };
  return {
    operation: 'DeleteItem',
    key: util.dynamodb.toMapValues({ id }),
    condition: util.transform.toDynamoDBConditionExpression(condition),
  };
}
```

For more information about the DynamoDB `DeleteItem` API, see the [DynamoDB API documentation](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_DeleteItem.html).