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Originally published on The Go Programming Language Blog, July 12, 2011. http://blog.golang.org/2011/07/error-handling-and-go.html Update #2547 R=golang-dev, r CC=golang-dev https://golang.org/cl/5475060
72 lines
1.6 KiB
Go
72 lines
1.6 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file contains the code snippets included in "Error Handling and Go."
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package main
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import (
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"net/http"
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"text/template"
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)
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type appError struct {
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Error error
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Message string
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Code int
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}
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// STOP OMIT
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type appHandler func(http.ResponseWriter, *http.Request) *appError
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func (fn appHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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if e := fn(w, r); e != nil { // e is *appError, not os.Error.
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c := appengine.NewContext(r)
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c.Errorf("%v", e.Error)
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http.Error(w, e.Message, e.Code)
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}
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}
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// STOP OMIT
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func viewRecord(w http.ResponseWriter, r *http.Request) *appError {
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c := appengine.NewContext(r)
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key := datastore.NewKey(c, "Record", r.FormValue("id"), 0, nil)
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record := new(Record)
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if err := datastore.Get(c, key, record); err != nil {
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return &appError{err, "Record not found", 404}
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}
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if err := viewTemplate.Execute(w, record); err != nil {
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return &appError{err, "Can't display record", 500}
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}
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return nil
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}
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// STOP OMIT
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func init() {
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http.Handle("/view", appHandler(viewRecord))
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}
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type ap struct{}
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func (ap) NewContext(*http.Request) *ctx { return nil }
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type ctx struct{}
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func (*ctx) Errorf(string, ...interface{}) {}
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var appengine ap
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type ds struct{}
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func (ds) NewKey(*ctx, string, string, int, *int) string { return "" }
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func (ds) Get(*ctx, string, *Record) error { return nil }
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var datastore ds
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type Record struct{}
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var viewTemplate *template.Template
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func main() {}
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