Interceptor Implementation

This guide explains how to implement interceptors in Goa, focusing on the flexibility provided by the interceptor pattern and the next function.

Implementation Structure

Goa generates type-safe interceptor interfaces based on your design. Each interceptor method follows this signature:

func (i *Interceptor) MethodName(ctx context.Context, info *InterceptorInfo, next goa.Endpoint) (any, error)

Where:

• ctx: The request context
• info: Type-safe access to payload and result attributes
• next: The wrapped endpoint (service method or next interceptor)

The Next Function

The next function is the key to interceptor flexibility. It represents the wrapped endpoint and can be called at any point in your interceptor code. This enables three main patterns: