How to Effectively Terminate HTTP Requests in Go?

Terminating HTTP Requests in Go

In Go, you can terminate an HTTP request by returning from the ServeHTTP() method of an HTTP handler. This approach allows you to end the request and send a response to the client.

Example:

http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    // Examine incoming parameters
    if !ok {
        str := `{"Result":"","Error":"No valid Var"}`
        fmt.Fprint(w, str)
        return // Terminate the request
    }

    // Continue normal API serving
})

Notes:

• Consider returning an HTTP error code instead of the default 200 OK when your API's input parameters are invalid. Use the http.Error() function for this purpose.

Example:

http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    // Examine incoming parameters
    if !ok {
        http.Error(w, `Invalid input params!`, http.StatusBadRequest) 
        return // Terminate the request
    }

    // Continue normal API serving
})

• For more control, you can set headers and return JSON error responses explicitly.

Example:

http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    // Examine incoming parameters
    if !ok {
        w.Header().Set("Content-Type", "application/json")
        w.WriteHeader(http.StatusBadRequest)
        str := `{"Result":"","Error":"No valid Var"}`
        fmt.Fprint(w, str)
        return // Terminate the request
    }

    // Continue normal API serving
})

Propagation of Errors:

If you encounter an error outside of ServeHTTP(), you must return that error state so that ServeHTTP() can terminate the request.

Example:

type params struct {
    // Field definitions for your parameters
}

func decodeParams(r *http.Request) (*params, error) {
    p := new(params)
    // Decode parameters
    if !ok {
        return nil, errors.New("Invalid params")
    }
    return p, nil
}

http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
    p, err := decodeParams(r)
    if err != nil {
        http.Error(w, `Invalid input params!`, http.StatusBadRequest)
        return // Terminate the request
    }

    // Continue normal API serving
})

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