Mapping Templates

A mapping template is used by the AWS API Gateway to understand and transform incoming or outgoing messages between APIs and backend services.

How are mapping templates used?

API Gateway Integrations

AWS API Gateway allows you to create RESTful APIs and integrate them with backend services, such as DynamoDB.

When defining an integration between your API and DynamoDB, you configure how requests and responses are transformed using mapping templates.

Request Mapping

For incoming requests to your API, you can define a request mapping template that transforms the incoming request payload or query parameters into a format suitable for DynamoDB operations. This allows you to extract specific data from the request, modify it, or restructure it to match the expected format of DynamoDB requests.

Response Mapping

Similarly, for outgoing responses from DynamoDB to the API Gateway, you can define a response mapping template. This template specifies how the DynamoDB response data should be transformed before being returned to the API caller. It allows you to modify the response structure, filter unwanted data, or extract specific elements to include in the API response.

Velocity Template Language (VTL) Syntax and Features

Velocity Template Language (VTL) is a scripting language used in mapping templates.

It provides a set of powerful features for data manipulation, conditional statements, looping, and variable assignment. With VTL, you can perform complex transformations and logic within your mapping templates.

Error Handling

Mapping templates also allow you to handle errors and exceptions that may occur during the transformation process. You can define error mappings to handle specific error conditions returned by DynamoDB and transform them into appropriate API responses with meaningful error messages or HTTP status codes.