errorhandling.go

package main

import (
	"fmt"
	"log"
	"net/http"

	"github.com/pkg/errors"
)

var ErrNotFound = errors.New("Page not found")
var ErrBadRequest = errors.New("Bad Request")

func handleError(resp *http.Response) error {
	switch resp.StatusCode {
	case 400:
		return ErrBadRequest
	case 404:
		return ErrNotFound
	}
	return nil
}

func getRequest() (int, error) {
	resp, err := http.Get("http://www.google.com/blabla")
	if err != nil {
		return 0, err
	}
	defer resp.Body.Close()
	err = handleError(resp)
	if err != nil {
		return 0, err
	}
	return resp.StatusCode, nil
}

func main() {
	code, err := getRequest()

	switch errors.Cause(err) {
	case ErrNotFound:
		fmt.Println("its not there")
	case ErrBadRequest:
		fmt.Println("oh no")
	default:
		// unknown error
		log.Fatalf("this was unexpected: %v\n", err)
	}
	fmt.Println(code)
}