目的:我有一个 xml 文档,其中包含许多混合内容 cdata 元素,我需要以编程方式编辑它们。令人烦恼的是,由于 cdata 元素具有其他/混合内容,默认的“,cdata”标记无法正常工作(根据 xml 规范)。如果您对此具体细节有疑问,请告诉我。
问题:在下面的简化示例中,我将其中包含 cdata 的元素标记为“,innerxml”,以便自己处理前缀/后缀。通过解组,一切都按预期工作,但是通过编组(编码),特殊字符被转义。当标签明确表示不转义时(通过“,innerxml”标签),为什么 EncodeElement 方法会转义特殊字符?当我在文档中读到此方法时,它让我参考 xml.Marshal 方法,其中包含以下内容:
带有标签“,innerxml”的字段是逐字写入的,不受通常的编组过程的影响。
示例:
这是代码(也可在 https://go.dev/play/p/MH_ONAVaG_1 获取):
package main
import (
"encoding/xml"
"fmt"
"strings"
)
var xmlFile string = `<?xml version="1.0" encoding="UTF-8"?>
<statusdb>
<status date="today">
<![CDATA[today is < yesterday]]>
</status>
<status date="yesterday">
<![CDATA[PM,
1. there are issues with the marshaller
2. i don't know how to solve them]]>
</status>
</statusdb>`
type statusDB struct {
Status []*status `xml:"status"`
}
type status struct {
Text string `xml:",innerxml"`
Date string `xml:"date,attr"`
}
type statusMarshaller status
func main() {
var projectStatus statusDB
err := xml.Unmarshal([]byte(xmlFile), &projectStatus)
if err != nil {
fmt.Println(err)
return
}
fmt.Println("In Go: \"" + projectStatus.Status[0].Text + "\"")
fmt.Println("In Go: \"" + projectStatus.Status[1].Text + "\"")
x, err := xml.MarshalIndent(projectStatus, "", " ")
if err != nil {
fmt.Println(err)
return
}
//why this is not printing properly
fmt.Printf("%s\n", x)
}
func (tagElement *status) UnmarshalXML(d *xml.Decoder, se xml.StartElement) error {
temp := statusMarshaller{}
d.DecodeElement(&temp, &se)
temp.Text = strings.TrimSpace(temp.Text)
temp.Text = strings.TrimPrefix(temp.Text, "<![CDATA[")
temp.Text = strings.TrimSuffix(temp.Text, "]]>")
*tagElement = status(temp)
return nil
}
func (tagElement status) MarshalXML(d *xml.Encoder, se xml.StartElement) error {
tagElement.Text = "<![CDATA[" + tagElement.Text + "]]>"
temp, _ := xml.Marshal(statusMarshaller(tagElement))
return d.EncodeElement(temp, se)
}
此代码返回以下内容:
In Go: "today is < yesterday"
In Go: "PM,
1. there are issues with the marshaller
2. i don't know how to solve them"
<statusDB>
<status><statusMarshaller date="today"><![CDATA[today is < yesterday]]></statusMarshaller></status>
<status><statusMarshaller date="yesterday"><![CDATA[PM,
 1. there are issues with the marshaller
 2. i don't know how to solve them]]></statusMarshaller></status>
</statusDB>
Program exited.
结论: 有人可以解释为什么 xml 包会这样做,以及潜在的解决方法是什么?
谢谢!
当然,如果包中的 cdata 允许混合元素,那就太好了,但现在我已经找到了我的解决方法,即上面的代码,进行了一些小更改,以便不在 marhshalXML 函数中的 statusMarshaller 类型上调用“marshal”。相反,我只将 tagElement 转换为 statusMarshaller 类型,然后对该元素进行编码。请参阅以下详细信息:
修订历史:
package main
import (
"encoding/xml"
"fmt"
"strings"
)
var xmlFile string = `<?xml version="1.0" encoding="UTF-8"?>
<statusdb>
<status date="today">
<![CDATA[today is < yesterday]]>
</status>
<status date="yesterday">
<![CDATA[PM,
1. there are issues with the marshaller
2. i don't know how to solve them]]>
</status>
</statusdb>`
type statusDB struct {
Status []*status `xml:"status"`
}
type status struct {
XMLName xml.Name
Text string `xml:",innerxml"`
Date string `xml:"date,attr"`
}
type statusMarshaller status
func main() {
var projectStatus statusDB
err := xml.Unmarshal([]byte(xmlFile), &projectStatus)
if err != nil {
fmt.Println(err)
return
}
fmt.Println("In Go: \"" + projectStatus.Status[0].Text + "\"")
fmt.Println("In Go: \"" + projectStatus.Status[1].Text + "\"")
x, err := xml.MarshalIndent(projectStatus, "", " ")
if err != nil {
fmt.Println(err)
return
}
//why this is not printing properly
fmt.Printf("%s\n", x)
}
func (tagElement *status) UnmarshalXML(d *xml.Decoder, se xml.StartElement) error {
temp := statusMarshaller{}
d.DecodeElement(&temp, &se)
temp.Text = strings.TrimSpace(temp.Text)
temp.Text = strings.TrimPrefix(temp.Text, "<![CDATA[")
temp.Text = strings.TrimSuffix(temp.Text, "]]>")
*tagElement = status(temp)
return nil
}
func (tagElement status) MarshalXML(d *xml.Encoder, se xml.StartElement) error {
tagElement.Text = "<![CDATA[" + tagElement.Text + "]]>"
temp := statusMarshaller(tagElement)
return d.EncodeElement(temp, se)
}