如何在反序列化时跳过元素？

huangapple
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英文:

How to skip elements when unmarshalling?

问题

如何在解组 XML 时删除 <Text Language="de">...</Text>（如下所示）？

我尝试使用 UnmarshalXML 方法跳过元素，但是这样做会跳过整个元素。

Play Golang 链接中的示例

  1. package main
  2.     
  3. import (
  4. 	"encoding/xml"
  5. 	"fmt"
  6. )
  8. type Root struct {
  9. 	Translation []Text `xml:"Texts>Text>Text"`
  10. }
  12. type Text struct {
  13. 	Language string `xml:"Language,attr"`
  14. 	Value    string `xml:"Value"`
  15. }
  17. func main() {
  18. 	foo := `
  19.         <Root>
  20.             <Texts>
  21.                 <Text>
  22.                     <Text Language="EN">
  23.                         <Value>One</Value>
  24.                     </Text>
  25.                     <Text Language="de">
  26.                         <Value>Eins</Value>
  27.                     </Text>
  28.                 </Text>
  29.             </Texts>
  30.         </Root>
  31.         `
  33. 	var root Root
  34. 	e := xml.Unmarshal([]byte(foo), &root)
  35. 	if e != nil {
  36. 		panic(e)
  37. 	}
  39. 	fmt.Printf("%+v\n", root)
  40. }
  42. func (t *Text) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
  43. 	tx := struct{ Language, Value string }{}
  44. 	
  45. 	if start.Attr[0].Value == "EN" {
  46. 		d.DecodeElement(&tx, &start)
  48.         // 在这里无法获取 Language 属性
  49. 		*t = Text{tx.Language, tx.Value}
  50.  		// fmt.Printf("hey: %+v %s\n", tx, start.Attr[0].Value)
  51. 	} else {
  52. 	    // 它输出了带有空字段的 DE 元素
  53. 	    d.Skip()
  54. 	}
  56. 	return nil
  57. }

当前输出:

  1. {Translation:[{Language: Value:One} {Language: Value:}]}

我想要的输出:

  1. {Translation:[{Language:EN Value:One}]}
英文:

How can I remove &lt;Text Language=&quot;de&quot;&gt;...&lt;/Text&gt; (as shown below) when unmarshaling XML?

I tried to skip the element with UnmarshalXML method, however, it's skipping the whole element when I do that.

Example in Play Golang Link

package main

  1. import (
  2. 	&quot;encoding/xml&quot;
  3. 	&quot;fmt&quot;
  4. )
  6. type Root struct {
  7. 	Translation []Text `xml:&quot;Texts&gt;Text&gt;Text&quot;`
  8. }
  10. type Text struct {
  11. 	Language string `xml:&quot;Language,attr&quot;`
  12. 	Value    string `xml:&quot;Value&quot;`
  13. }
  15. func main() {
  16. 	foo := `
  17.         &lt;Root&gt;
  18.             &lt;Texts&gt;
  19.                 &lt;Text&gt;
  20.                     &lt;Text Language=&quot;EN&quot;&gt;
  21.                         &lt;Value&gt;One&lt;/Value&gt;
  22.                     &lt;/Text&gt;
  23.                     &lt;Text Language=&quot;de&quot;&gt;
  24.                         &lt;Value&gt;Eins&lt;/Value&gt;
  25.                     &lt;/Text&gt;
  26.                 &lt;/Text&gt;
  27.             &lt;/Texts&gt;
  28.         &lt;/Root&gt;
  29.         `
  31. 	var root Root
  32. 	e := xml.Unmarshal([]byte(foo), &amp;root)
  33. 	if e != nil {
  34. 		panic(e)
  35. 	}
  37. 	fmt.Printf(&quot;%+v\n&quot;, root)
  38. }
  40. func (t *Text) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
  41. 	tx := struct{ Language, Value string }{}
  42. 	
  43. 	if start.Attr[0].Value == &quot;EN&quot; {
  44. 		d.DecodeElement(&amp;tx, &amp;start)
  46.         // I couldn&#39;t got Language attr here
  47. 		*t = Text{tx.Language, tx.Value}
  48.  		// fmt.Printf(&quot;hey: %+v %s\n&quot;, tx, start.Attr[0].Value)
  49. 	} else {
  50. 	    // It outputs DE element with empty fields
  51. 	    d.Skip()
  52. 	}
  54. 	return nil
  55. }

Current Output:

  1. {Translation:[{Language: Value:One} {Language: Value:}]}

What I Want:

  1. {Translation:[{Language:EN Value:One}]}

答案1

得分: 2

你的代码中存在问题，导致第二个元素为空。你可以尝试以下修改：

  1. package main
  3. import (
  4. 	"encoding/xml"
  5. 	"fmt"
  6. )
  8. type Root struct {
  9. 	Translation Text `xml:"Texts>Text>Text"`
  10. }
  12. type Text []struct {
  13. 	Language string `xml:"Language,attr"`
  14. 	Value    string `xml:"Value"`
  15. }
  17. func main() {
  18. 	foo := `
  19.         <Root>
  20.             <Texts>
  21.                 <Text>
  22.                     <Text Language="EN">
  23.                         <Value>One</Value>
  24.                     </Text>
  25.                     <Text Language="de">
  26.                         <Value>Eins</Value>
  27.                     </Text>
  28.                 </Text>
  29.             </Texts>
  30.         </Root>
  31.         `
  33. 	var root Root
  34. 	e := xml.Unmarshal([]byte(foo), &root)
  35. 	if e != nil {
  36. 		panic(e)
  37. 	}
  39. 	fmt.Printf("%+v\n", root)
  40. }
  42. func (t *Text) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
  43. 	tx := []struct {
  44. 		Language string `xml:"Language,attr"`
  45. 		Value    string `xml:"Value"`
  46. 	}{}
  47. 	d.DecodeElement(&tx, &start)
  49. 	tSl := *t
  50. 	for _, elem := range tx {
  51. 		switch elem.Language {
  52. 		case "EN":
  53. 			tSl = append(tSl, struct {
  54. 				Language string `xml:"Language,attr"`
  55. 				Value    string `xml:"Value"`
  56. 			}{elem.Language, elem.Value})
  57. 		default:
  58. 			d.Skip()
  59. 		}
  60. 	}
  61. 	*t = tSl
  62. 	return nil
  63. }

输出结果应为：

  1. {Translation:[{Language:EN Value:One}]}
英文:

You're operating too low by unmarshalling at the Text Level - you're still Unmarshalling 2 Texts elements which is why you are seeing an empty second element. You could try something like this:

  1. package main
  2. import (
  3. &quot;encoding/xml&quot;
  4. &quot;fmt&quot;
  5. )
  6. type Root struct {
  7. Translation Text `xml:&quot;Texts&gt;Text&gt;Text&quot;`
  8. }
  9. type Text []struct {
  10. Language string `xml:&quot;Language,attr&quot;`
  11. Value    string `xml:&quot;Value&quot;`
  12. }
  13. func main() {
  14. foo := `
  15. &lt;Root&gt;
  16. &lt;Texts&gt;
  17. &lt;Text&gt;
  18. &lt;Text Language=&quot;EN&quot;&gt;
  19. &lt;Value&gt;One&lt;/Value&gt;
  20. &lt;/Text&gt;
  21. &lt;Text Language=&quot;de&quot;&gt;
  22. &lt;Value&gt;Eins&lt;/Value&gt;
  23. &lt;/Text&gt;
  24. &lt;/Text&gt;
  25. &lt;/Texts&gt;
  26. &lt;/Root&gt;
  27. `
  28. var root Root
  29. e := xml.Unmarshal([]byte(foo), &amp;root)
  30. if e != nil {
  31. panic(e)
  32. }
  33. fmt.Printf(&quot;%+v\n&quot;, root)
  34. }
  35. func (t *Text) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
  36. tx := []struct{
  37. Language string `xml:&quot;Language,attr&quot;`
  38. Value    string `xml:&quot;Value&quot;`
  39. }{}
  40. d.DecodeElement(&amp;tx, &amp;start)
  41. tSl := *t
  42. for _, elem := range tx {
  43. switch elem.Language {
  44. case &quot;EN&quot;:
  45. tSl = append(tSl, struct{
  46. Language string `xml:&quot;Language,attr&quot;`
  47. Value    string `xml:&quot;Value&quot;`}{elem.Language, elem.Value})
  48. default:
  49. d.Skip()
  50. }
  51. }
  52. *t = tSl
  53. return nil
  54. }

Output:

  1. {Translation:[{Language:EN Value:One}]}

huangapple
  • 本文由 发表于 2017年6月9日 18:48:22
  • 转载请务必保留本文链接：https://go.coder-hub.com/44455853.html
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