How do I unmarshal nested XML elements into an array?

问题

My XML contains an array of predefined elements, but I can't pick up the array. Here is the XML structure:

var xml_data = `<Parent>
                   <Val>Hello</Val>
                   <Children>
                      <Child><Val>Hello</Val></Child>
                      <Child><Val>Hello</Val></Child>
                      <Child><Val>Hello</Val></Child>
                   </Children>
                </Parent>`

Here is the full code and here is the playground link. Running this will pick up Parent.Val, but not Parent.Children.

package main

import (
    "fmt"
    "encoding/xml"
)

func main() {

    container := Parent{}
    err := xml.Unmarshal([]byte(xml_data), &container)

    if err != nil {
        fmt.Println(err)
    } else {
        fmt.Println(container)  
    }
}

var xml_data = `<Parent>
                   <Val>Hello</Val>
                   <Children>
                      <Child><Val>Hello</Val></Child>
                      <Child><Val>Hello</Val></Child>
                      <Child><Val>Hello</Val></Child>
                   </Children>
                </Parent>`

type Parent struct {
    Val string
    Children []Child
}

type Child struct {
    Val string
}

EDIT: I simplified the problem a bit here. Basically I can't unmarshal any array, not just of predefined structure. Below is the updated work code. In that example, only one item ends up in the container interface.

func main() {

    container := []Child{}
    err := xml.Unmarshal([]byte(xml_data), &container)

    if err != nil {
        fmt.Println(err)
    } else {
        fmt.Println(container)  
    }

    /* 
        ONLY ONE CHILD ITEM GETS PICKED UP
    */
}

var xml_data = `
            <Child><Val>Hello</Val></Child>
            <Child><Val>Hello</Val></Child>
            <Child><Val>Hello</Val></Child>
        `

type Child struct {
    Val string
}

回答1:

For this kind of nesting, you'll need also a struct for Children element:

package main

import (
    "fmt"
    "encoding/xml"
)

func main() {

    container := Parent{}
    err := xml.Unmarshal([]byte(xml_data), &container)

    if err != nil {
        fmt.Println(err)
    } else {
        fmt.Println(container)  
    }
}

var xml_data = `<Parent>
            <Val>Hello</Val>
            <Children>
                <Child><Val>Hello</Val></Child>
                <Child><Val>Hello</Val></Child>
                <Child><Val>Hello</Val></Child>
            </Children>
        </Parent>`

type Parent struct {
    Val string
    Children Children
}

type Children struct {
    Child []Child
}

type Child struct {
    Val string
}

Also pasted here: Go Playground

Note that your code would work (after changing variable name from Children to Child) with this kind of XML structure:

<Parent>
    <Val>Hello</Val>
    <Child><Val>Hello</Val></Child>
    <Child><Val>Hello</Val></Child>
    <Child><Val>Hello</Val></Child>
</Parent>

回答2:

type Parent struct {
    Val string
    Children []Child  `xml:"Children>Child"`  //Just use the '>'
}

来源：https://stackoverflow.com/questions/34941539/how-do-i-unmarshal-nested-xml-elements-into-an-array

标签

xml

unmarshalling