Request Body
Explore how to handle complex request bodies in AWS API Gateway by leveraging Velocity templates for data transformation. Understand the use of the $context variable, programming constructs like #set and #foreach, and how to implement mappings on the AWS console. This lesson helps you build efficient APIs without extra latency or cost by avoiding unnecessary Lambda functions.
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Payload mapping
Query strings and path parameters are pretty simple to isolate and transform. However, the complexity increases exponentially when we look into the API payload. The request body could be a complex JSON, XML, or just a blob. It’s challenging to extract details from it and transform them per the target API's requirements. Let’s now dig deeper to understand the immense potential of this feature.
API Gateway simplifies this process using Apache Velocity templates, which provide a concise syntax for data transformation. The templates are intuitive, learnable simply by reading a few lines of code.
Velocity template example
Let’s check out an example where we use a Velocity template to construct a payload of the API integration. The below code uses an HTTP integration with a public API for IP geolocation. The API returns the ...