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AWS AppSync resolver mapping template utility reference

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AWS AppSync resolver mapping template utility reference - AWS AppSync GraphQL
Note

We now primarily support the APPSYNC_JS runtime and its documentation. Please consider using the APPSYNC_JS runtime and its guides here.

AWS AppSync defines a set of utilities that you can use within a GraphQL resolver to simplify interactions with data sources. Some of these utilities are for general use with any data source, such as generating IDs or timestamps. Others are specific to a type of data source. The following utilities are available:

  • Utility helpers in $util - The $util variable contains general utility methods to help you work with data. Unless otherwise specified, all utilities use the UTF-8 character set.

  • AppSync directives - AppSync exposes directives to facilitate developer productivity when writing in VTL.

  • Time helpers in $util.time - The $util.time variable contains datetime methods to help generate timestamps, convert between datetime formats, and parse datetime strings. The syntax for datetime formats is based on DateTimeFormatter, which you can reference for further documentation.

  • List helpers in $util.list - $util.list contains methods to help with common List operations such as removing or retaining items from a list for filtering use cases.

  • Map helpers in $util.map - $util.map contains methods to help with common Map operations such as removing or retaining items from a Map for filtering use cases.

  • DynamoDB helpers in $util.dynamodb - $util.dynamodb contains helper methods that make it easier to write and read data to Amazon DynamoDB, such as automatic type mapping and formatting.

  • Amazon RDS helpers in $util.rds - $util.rds contains helper methods that format RDS operations by getting rid of extraneous data in result outputs.

  • HTTP helpers in $util.http - The $util.http utility provides helper methods that you can use to manage HTTP request parameters and to add response headers.

  • XML helpers in $util.xml - $util.xml contains helper methods that can make it easier to translate XML responses to JSON or a Dictionary.

  • Transformation helpers in $util.transform - $util.transform contains helper methods that make it easier to perform complex operations against data sources, such as DynamoDB filter operations.

  • Math helpers in $util.math - $util.math contains methods to help with common Math operations.

  • String helpers in $util.str - $util.str contains methods to help with common String operations.

  • Extensions - $extensions contains a set of methods to make additional actions within your resolvers.

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