OpenFeign/feign

incomplete Object information when serialize object with Gson

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#2,485 opened on Jul 24, 2024

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 (3 comments) (0 reactions) (0 assignees)Java (9,070 stars) (1,911 forks)batch import
bughelp wanted

Description


    @PostMapping("/message/send?access_token={access_token}")
    MessageResponseDTO send(@RequestParam("access_token") String accessToken, @RequestBody AbsMessage message);

Such as the code, I need to call it,the interface has different performance depends on the Object passed. However AbsMessage is a abstract class,when I call it need to pass an object which instance of AbsMessage. But the reuest body doesn't conatin any field from the runtime sub class whic I passed. All fields are from the abstract class. I find the cause at last.

  GsonEncoder#encode(Object object, Type bodyType, RequestTemplate template)
  @Override
  public void encode(Object object, Type bodyType, RequestTemplate template) {
    template.body(gson.toJson(object, bodyType));
  }

It serializes object with the type which declared in the function,not runtime type of the passed object. If gson.toJson(object),It appears normal.

Contributor guide

Tech stack
java
Domain
api
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
needs maintainer response
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaGsonFeign basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75
Research direction
Inspect the GsonEncoder class in the feign gson module. The encode method currently uses gson.toJson(object, bodyType) which uses the declared type. Change it to gson.toJson(object) to serialize using the runtime type. Ensure tests are added to verify that subclass fields are included in serialization.