huma.WithContext() destroys original humago Context

[akhayyat]

I'm using humago.

I have a chain of middleware, and one of the later ones needs to use humago.Unwrap() to access the underlying http.Request to log some attributes that are not available in huma.Context (e.g. useragent).

One of the earlier middleware is injecting a key into the request context (context.Context), which naturally creates a new context. The new context is then reattached to the huma context using huma.WithContext().

However, after that point, humago.Unwrap(ctx) panics with the error: not a humago context.

If I move the panicking middleware up the chain so that it runs before the middleware that modifies the context, it works fine.

Here is a minimal example to reproduce the problem (TestMiddleware is the one that panics):

package main

import (
	"context"
	"net/http"

	"github.com/danielgtaylor/huma/v2"
	"github.com/danielgtaylor/huma/v2/adapters/humago"
)

func main() {
	router := http.NewServeMux()
	api := humago.New(router, huma.DefaultConfig("Campaigns", "1"))

	api.UseMiddleware(UpdateCtx, TestMiddleware)

	huma.Get(api, "/", handler)
	http.ListenAndServe(":8080", router)
}

type key struct{}

func UpdateCtx(ctx huma.Context, next func(huma.Context)) {
	// Inject key/value into context.
	ridCtx := context.WithValue(ctx.Context(), key{}, "value")
	ctx = huma.WithContext(ctx, ridCtx)
	next(ctx)
}

func TestMiddleware(ctx huma.Context, next func(huma.Context)) {
	req, _ := humago.Unwrap(ctx)
	println("Useragent:", req.UserAgent())

	next(ctx)
}

type Output struct {
	Body struct {
		Message string
	}
}

func handler(ctx context.Context, i *struct{}) (*Output, error) {
	output := Output{}
	output.Body.Message = "Hello"
	return &output, nil
}

[akhayyat]

I also tried replacing:

	ridCtx := context.WithValue(ctx.Context(), key{}, "value")
	ctx = huma.WithContext(ctx, ridCtx)

with:

	ctx = huma.WithValue(ctx, key{}, "value")

but still got the same panic.

[akhayyat]

This seems to work:

func WithContext(ctx huma.Context, reqCtx context.Context) huma.Context {
	req, resp := humago.Unwrap(ctx)
	req = req.WithContext(reqCtx)
	ctx = humago.NewContext(ctx.Operation(), req, resp)
	return ctx
}

Usage:

func(ctx huma.Context) {
	...
	ctx = WithContext(ctx, context.WithValue(ctx.Context(), key{}, "value"))
}

It'd be great if huma.WithContext() and huma.WithValue() were fixed to preserve humago context.

[akhayyat]

The workaround in the previous comment seems to break testing using the humatest package. Tests panic with not a humago context.