example_marshaling_test.go

Documentation: encoding/xml

		 1  // Copyright 2018 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  package xml_test
		 6  
		 7  import (
		 8  	"encoding/xml"
		 9  	"fmt"
		10  	"log"
		11  	"strings"
		12  )
		13  
		14  type Animal int
		15  
		16  const (
		17  	Unknown Animal = iota
		18  	Gopher
		19  	Zebra
		20  )
		21  
		22  func (a *Animal) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
		23  	var s string
		24  	if err := d.DecodeElement(&s, &start); err != nil {
		25  		return err
		26  	}
		27  	switch strings.ToLower(s) {
		28  	default:
		29  		*a = Unknown
		30  	case "gopher":
		31  		*a = Gopher
		32  	case "zebra":
		33  		*a = Zebra
		34  	}
		35  
		36  	return nil
		37  }
		38  
		39  func (a Animal) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
		40  	var s string
		41  	switch a {
		42  	default:
		43  		s = "unknown"
		44  	case Gopher:
		45  		s = "gopher"
		46  	case Zebra:
		47  		s = "zebra"
		48  	}
		49  	return e.EncodeElement(s, start)
		50  }
		51  
		52  func Example_customMarshalXML() {
		53  	blob := `
		54  	<animals>
		55  		<animal>gopher</animal>
		56  		<animal>armadillo</animal>
		57  		<animal>zebra</animal>
		58  		<animal>unknown</animal>
		59  		<animal>gopher</animal>
		60  		<animal>bee</animal>
		61  		<animal>gopher</animal>
		62  		<animal>zebra</animal>
		63  	</animals>`
		64  	var zoo struct {
		65  		Animals []Animal `xml:"animal"`
		66  	}
		67  	if err := xml.Unmarshal([]byte(blob), &zoo); err != nil {
		68  		log.Fatal(err)
		69  	}
		70  
		71  	census := make(map[Animal]int)
		72  	for _, animal := range zoo.Animals {
		73  		census[animal] += 1
		74  	}
		75  
		76  	fmt.Printf("Zoo Census:\n* Gophers: %d\n* Zebras:	%d\n* Unknown: %d\n",
		77  		census[Gopher], census[Zebra], census[Unknown])
		78  
		79  	// Output:
		80  	// Zoo Census:
		81  	// * Gophers: 3
		82  	// * Zebras:	2
		83  	// * Unknown: 3
		84  }
		85
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