Using render.JSON with no http Request object throws an error

Open
  • Is something wrong?
#28 0 comments 0 reactions 0 assignees View on GitHub

@team-humaki is already working on this.

Since Sep 16, 2026.

  • #67 by @team-humaki — open

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
50/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Stale
Tech stack
go
Domain
api, backend

Research direction

Start in responder.go at line 103, where JSON accesses the request context, and reproduce the failure with the wrapper test shown in the issue. Check the nil-request path and verify that the response body is written without a panic while preserving the requested status behavior.

Written by the indexing model from the issue text.

Description

In the responder, render.JSON() function takes in an "http.Request" object which will be used to get the http response status code

I'm customizing the behavior of the function, by wrapping it with a wrapper function in my project. So I can call one function to pass in the response body as well as the status code, like so

func (r *responder) JSON(w http.ResponseWriter, v interface{}, s int) {
	// Write http response status
	w.WriteHeader(s)
	render.JSON(w, nil, v)
}

When "nil" is passed is shown above instead of an http.Request object, the function throws an error.

--- FAIL: TestJSON (0.00s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0xf0 pc=0x12a9ca0]

Here is the test I wrote to test the wrapper:

func TestJSON(t *testing.T) {
	type mockResponse struct {
		MockField string `json:"field"`
	}
	responder := NewResponder()

	recorder := httptest.NewRecorder()
	responder.JSON(recorder, mockResponse{MockField: "test"}, http.StatusOK)
	assert.Equal(t, recorder.Code, 200)
	assert.JSONEq(t, `{"field": "test"}`, recorder.Body.String())
}

I did some debugging, it seems like the error is caused by line 103 in JSON function in responder.go, which is the following:

	if status, ok := r.Context().Value(StatusCtxKey).(int); ok {
		w.WriteHeader(status)
	}

How about adding a check for when the request object is nil, it skips this whole check and only writes the body to the buffer?

Dominant language
Go
Stars
340
Forks
69
No merged PRs in 30d

Getting set up

This project ships no dev container, Dockerfile or contributing guide, so setting up is up to you: start from its README, and see our first-contribution guide for the general steps.

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from go-chi/render

All issues in go-chi/render

Similar issues

More Go issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.