# AWS AppSync resolver mapping template reference for EventBridge
<a name="resolver-mapping-template-reference-eventbridge"></a>

**Note**  
We now primarily support the APPSYNC\$1JS runtime and its documentation. Please consider using the APPSYNC\$1JS runtime and its guides [here](https://docs.aws.amazon.com/appsync/latest/devguide/resolver-reference-js-version.html).

The AWS AppSync resolver mapping template used with the EventBridge data source allows you to send custom events to the Amazon EventBridge bus.

## Request mapping template
<a name="request-mapping-template"></a>

The `PutEvents` request mapping template allows you to send multiple custom events to an EventBridge event bus. The mapping document has the following structure:

```
{
    "version" : "2018-05-29", 
    "operation" : "PutEvents",
    "events" : [{}]
}
```

The following is an example of a request mapping template for EventBridge: 

```
{
    "version": "2018-05-29",
    "operation": "PutEvents",
    "events": [{
        "source": "com.mycompany.myapp",
        "detail": {
            "key1" : "value1",
            "key2" : "value2"
        },
        "detailType": "myDetailType1"
    },
    {
        "source": "com.mycompany.myapp",
        "detail": {
            "key3" : "value3",
            "key4" : "value4"
        },
        "detailType": "myDetailType2",
        "resources" : ["Resource1", "Resource2"],
        "time" : "2023-01-01T00:30:00.000Z"
    }
    
    ]
}
```

## Response mapping template
<a name="response-mapping-template"></a>

If the `PutEvents` operation is successful, the response from EventBridge is included in the `$ctx.result`:

```
#if($ctx.error)
  $util.error($ctx.error.message, $ctx.error.type, $ctx.result)
#end
  $util.toJson($ctx.result)
```

Errors that occur while performing `PutEvents` operations such as `InternalExceptions` or `Timeouts` will appear in `$ctx.error`. For a list of EventBridge's common errors, see the [EventBridge common error reference](https://docs.aws.amazon.com/eventbridge/latest/APIReference/CommonErrors.html).

The `result` will be in the following format:

```
{
    "Entries" [
        {
            "ErrorCode" : String,
            "ErrorMessage" : String,
            "EventId" : String
        }
    ],
    "FailedEntryCount" : number
}
```
+ **Entries**

  The ingested event results, both successful and unsuccessful. If the ingestion was successful, the entry has the `EventID` in it. Otherwise, you can use the `ErrorCode` and `ErrorMessage` to identify the problem with the entry.

  For each record, the index of the response element is the same as the index in the request array.
+ **FailedEntryCount**

  The number of failed entries. This value is represented as an integer.

For more information about the response of `PutEvents`, see [PutEvents](https://docs.aws.amazon.com/eventbridge/latest/APIReference/API_PutEvents.html#API_PutEvents_ResponseElements).

**Example sample response 1**

The following example is a `PutEvents` operation with two successful events:

```
{
    "Entries" : [ 
        {
            "EventId": "11710aed-b79e-4468-a20b-bb3c0c3b4860"
        }, 
        {
            "EventId": "d804d26a-88db-4b66-9eaf-9a11c708ae82"
        }
    ],
    "FailedEntryCount" : 0
}
```

**Example sample response 2**

The following example is a `PutEvents` operation with three events, two successes and one fail:

```
{
    "Entries" : [ 
        {
            "EventId": "11710aed-b79e-4468-a20b-bb3c0c3b4860"
        }, 
        {
            "EventId": "d804d26a-88db-4b66-9eaf-9a11c708ae82"
        },
        {
            "ErrorCode" : "SampleErrorCode",
            "ErrorMessage" : "Sample Error Message"
        }
    ],
    "FailedEntryCount" : 1
}
```

## `PutEvents` fields
<a name="putevents-field"></a>

`PutEvents` contains the following mapping template fields:
+ **Version**

  Common to all request mapping templates, the `version` field defines the version that the template uses. This field is required. The value `2018-05-29` is the only version supported for the EventBridge mapping templates.
+ **Operation**

  The only supported operation is `PutEvents`. This operation allows you to add custom events to your event bus.
+ **Events**

  An array of events that will be added to the event bus. This array should have an allocation of 1 - 10 items.

  The `Event` object is a valid JSON object that has the following fields:
  + `"source"`: A string that defines the source of the event.
  + `"detail"`: A JSON object that you can use to attach information about the event. This field can be an empty map ( `{ }` ).
  + `"detailType`: A string that identifies the type of event.
  + `"resources"`: A JSON array of strings that identifies resources involved in the event. This field can be an empty array.
  + `"time"`: The event timestamp provided as a string. This should follow the [RFC3339](https://www.rfc-editor.org/rfc/rfc3339.txt) timestamp format.

The snippets below are some examples of valid `Event` objects:

**Example 1**

```
{
    "source" : "source1",
    "detail" : {
        "key1" : [1,2,3,4],
        "key2" : "strval"
    },
    "detailType" : "sampleDetailType",
    "resources" : ["Resouce1", "Resource2"],
    "time" : "2022-01-10T05:00:10Z"
}
```

**Example 2**

```
{
    "source" : "source1",
    "detail" : {},
    "detailType" : "sampleDetailType"
}
```

**Example 3**

```
{
    "source" : "source1",
    "detail" : {
        "key1" : 1200
    },
    "detailType" : "sampleDetailType",
    "resources" : []
}
```