Amazon AppSync
resolver mapping template reference for None
data source
Note
We now primarily support the APPSYNC_JS runtime and its documentation. Please consider using the APPSYNC_JS runtime and its guides here.
The Amazon AppSync resolver mapping template used with the data source of type None, enables you to shape requests for Amazon AppSync local operations.
Request mapping template
The mapping template is simple and enables you to pass as much context information as
possible via the payload
field.
{ "version": string, "payload": any type }
Here is the JSON schema representation of the request mapping template, once resolved:
{ "definitions": {}, "$schema": "https://json-schema.org/draft-06/schema#", "$id": "https://aws.amazon.com/appsync/request-mapping-template.json", "type": "object", "properties": { "version": { "$id": "/properties/version", "type": "string", "enum": [ "2018-05-29" ], "title": "The Mapping template version.", "default": "2018-05-29" }, "payload": {} }, "required": [ "version" ], "additionalProperties": false }
Here is an example where the field arguments are passed via the VTL context
property $context.arguments
:
{ "version": "2018-05-29", "payload": $util.toJson($context.arguments) }
The value of the payload
field will be forwarded to the response mapping
template and available on the VTL context property
($context.result
).
This is an example representing the interpolated value of the payload
field:
{ "id": "postId1" }
Version
Common to all request mapping templates, the version
field defines the version used
by the template.
The version
field is required.
Example:
"version": "2018-05-29"
Payload
The payload
field is a container that can be used to pass any well-formed
JSON to the response mapping template.
The payload
field is optional.
Response mapping template
Because there is no data source, the value of the payload
field will be
forwarded to the response mapping template and set on the context
object
that is available via the VTL $context.result
property.
If the shape of the payload
field value exactly matches the shape of the
GraphQL type, you can forward the response using the following response mapping
template:
$util.toJson($context.result)
There are no required fields or shape restrictions that apply to the response mapping template. However, because GraphQL is strongly typed, the resolved mapping template must match the expected GraphQL type.