中间件错误处理

Question

I have a chain of claw http.Handler middlewares, where my first handler might write an error response:

http.Error(w, err.Error(), http.StatusUnauthorized)

However my other middlewares continue executing, but I don't want it to. What is the best way to go about this? I tried checking the status header after calling http.Error(), to see if it is other than a 200:

status := w.Header().Get("Status")

but status is an empty string.

Answer 1

You can use a "naked" return just after your error to stop the middleware chain execution.

From http documentation:

Error replies to the request with the specified error message and HTTP code. It does not otherwise end the request; the caller should ensure no further writes are done to w. The error message should be plain text.

From this Custom Handlers and Avoiding Globals in Go Web Applications :

func myHandler(w http.ResponseWriter, r *http.Request) {
    session, err := store.Get(r, "myapp")
    if err != nil {
        http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
        return // Forget to return, and the handler will continue on
    }
    .../...
}