// Copyright 2016 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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package json_test
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import (
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"encoding/json"
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"fmt"
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"log"
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"strings"
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)
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type Animal int
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const (
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Unknown Animal = iota
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Gopher
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Zebra
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)
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func (a *Animal) UnmarshalJSON(b []byte) error {
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var s string
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if err := json.Unmarshal(b, &s); err != nil {
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return err
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}
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switch strings.ToLower(s) {
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default:
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*a = Unknown
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case "gopher":
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*a = Gopher
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case "zebra":
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*a = Zebra
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}
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return nil
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}
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func (a Animal) MarshalJSON() ([]byte, error) {
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var s string
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switch a {
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default:
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s = "unknown"
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case Gopher:
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s = "gopher"
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case Zebra:
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s = "zebra"
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}
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return json.Marshal(s)
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}
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func Example_customMarshalJSON() {
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blob := `["gopher","armadillo","zebra","unknown","gopher","bee","gopher","zebra"]`
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var zoo []Animal
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if err := json.Unmarshal([]byte(blob), &zoo); err != nil {
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log.Fatal(err)
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}
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census := make(map[Animal]int)
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for _, animal := range zoo {
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census[animal] += 1
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}
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fmt.Printf("Zoo Census:\n* Gophers: %d\n* Zebras: %d\n* Unknown: %d\n",
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census[Gopher], census[Zebra], census[Unknown])
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// Output:
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// Zoo Census:
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// * Gophers: 3
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// * Zebras: 2
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// * Unknown: 3
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}
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