spring-cloud/spring-cloud-gateway

Modify Request Body for a GET request

Open

#1147 opened on Jul 3, 2019

View on GitHub
 (7 comments) (0 reactions) (0 assignees)Java (4,284 stars) (3,204 forks)batch import
enhancementhelp wanted

Description

We currently have custom code for modifying request body which works but I want to move to the standard ModifyRequestBodyGatewayFilterFactory.

We have a scenario where Spring Cloud Gateway received a GET request and we need call an internal GraphQL api with a POST and a request body.

ModifyRequestBodyGatewayFilterFactory works great if there is a body present in the original request but doesn't apply the rewriteFunction when there is no body on GET requests.

I am using v2.1.2.RELEASE and I have hacked together a change to ModifyRequestBodyGatewayFilterFactory which works for me:

Mono<?> modifiedBody = serverRequest.bodyToMono(inClass)
        .defaultIfEmpty("") //added this line
        .flatMap(o -> config.rewriteFunction.apply(exchange, o));

I appreciate that the ModifyRequestBodyGatewayFilterFactory is beta, but would it be possible to support adding a body for GET requests in the future?

Contributor guide

Tech stack
javaspringgraphql
Domain
backendapi
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
JavaSpring Cloud GatewayReactive programming
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Examine the current implementation of `ModifyRequestBodyGatewayFilterFactory` in the spring cloud gateway repository. The user's proposed fix is to add `.defaultIfEmpty("")` in the `filter` method to allow body rewriting when original request body is empty (typical for GET requests). Implement this change and ensure it does not break existing behavior for POST requests with a body. Write unit tests covering both scenarios and verify the filter works with the standard `ModifyRequestBodyGatewayFilterFactory`. Refer to the linked issue for additional context on the expected behavior.