| // compile |
| |
| // Copyright 2011 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // This file contains the code snippets included in "Error Handling and Go." |
| |
| package main |
| |
| import ( |
| "net/http" |
| "text/template" |
| ) |
| |
| type appError struct { |
| Error error |
| Message string |
| Code int |
| } |
| |
| // STOP OMIT |
| |
| type appHandler func(http.ResponseWriter, *http.Request) *appError |
| |
| func (fn appHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) { |
| if e := fn(w, r); e != nil { // e is *appError, not error. |
| c := appengine.NewContext(r) |
| c.Errorf("%v", e.Error) |
| http.Error(w, e.Message, e.Code) |
| } |
| } |
| |
| // STOP OMIT |
| |
| func viewRecord(w http.ResponseWriter, r *http.Request) *appError { |
| c := appengine.NewContext(r) |
| key := datastore.NewKey(c, "Record", r.FormValue("id"), 0, nil) |
| record := new(Record) |
| if err := datastore.Get(c, key, record); err != nil { |
| return &appError{err, "Record not found", 404} |
| } |
| if err := viewTemplate.Execute(w, record); err != nil { |
| return &appError{err, "Can't display record", 500} |
| } |
| return nil |
| } |
| |
| // STOP OMIT |
| |
| func init() { |
| http.Handle("/view", appHandler(viewRecord)) |
| } |
| |
| type ap struct{} |
| |
| func (ap) NewContext(*http.Request) *ctx { return nil } |
| |
| type ctx struct{} |
| |
| func (*ctx) Errorf(string, ...interface{}) {} |
| |
| var appengine ap |
| |
| type ds struct{} |
| |
| func (ds) NewKey(*ctx, string, string, int, *int) string { return "" } |
| func (ds) Get(*ctx, string, *Record) error { return nil } |
| |
| var datastore ds |
| |
| type Record struct{} |
| |
| var viewTemplate *template.Template |
| |
| func main() {} |