Decode XML string into struct

Question

I've the following xml:

<DOC>
<SubGroup1>
    <Value1>ABC123</Value1>
    <Value2>ABC123</Value2>
    <Value3>ABC123</Value3>
    <Value4>ABC123</Value4>
</SubGroup1>
<SubGroup2>
    <TheTag MyTagAttr="ABC123">
        <Value1>ABC123</Value1>
        <Value2>ABC123</Value2>
        <Value3>ABC123</Value3>
        <Value4 MyTagAttr="ABC123">ABC123</Value4>
        <Value5>ABC123</Value5>
        <Value6>ABC123</Value6>
        <Value7>ABC123</Value7>
        <Value8>ABC123</Value8>
        <Value9>ABC123</Value9>
    </TheTag>
</SubGroup2>
</DOC>

And I need to decode into this struct:

type TheTag struct {
    XMLName xml.Name `xml:"SubGroup2>TheTag"`

    Value1  string  `xml:"Value1"`
    Value2  string  `xml:"Value2"`
}

But I'm not able to decode properly this subelement into the struct.

I'm getting the following error:

error decoding message content: %!w(xml.UnmarshalError=expected element type <SubGroup2>TheTag> but have <DOC>)

My code is available here on Go Playgroud: https://go.dev/play/p/O688qTBARJm

Thanks in advance!

Stéphane Jeandeaux · Accepted Answer · 2023-02-08 13:30:00Z

2

You should probably move the tags.

type TheTag struct {
  XMLName xml.Name `xml:"DOC"`

  Value1 string `xml:"SubGroup2>TheTag>Value1"`
  Value2 string `xml:"SubGroup2>TheTag>Value2"`
}

answered Feb 8, 2023 at 13:30

Stéphane Jeandeaux

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5 Comments

jsfelipearaujo Over a year ago

Hi Stéphane, your suggestion works, thanks! But how about the attributes? Do you have any clue about how to load these values?

kostix Over a year ago

@jsfelipearaujo, sorry for being glib, but have you read the package documentation? SO is not a service for reciting it, really. In particular, see the process of unmarshaling.

jsfelipearaujo Over a year ago

@kostix, yes I did. But there is no mention about how to read attributes from sub-elements using the path syntax.

kostix Over a year ago

@jsfelipearaujo, «If the XML element has an attribute whose name matches a struct field name with an associated tag containing ",attr" or the explicit name in a struct field tag of the form "name,attr", Unmarshal records the attribute value in that field.» and then «If the XML element contains a sub-element whose name matches the prefix of a tag formatted as "a" or "a>b>c", <…>»–the 1st explains name,attr, and the second explains how to format name there to refer to a nested element.

balki Over a year ago

stackoverflow.com/questions/18662730/…

Alexandr Kamenev · Accepted Answer · 2023-02-09 05:03:09Z

0

You can use the library github.com/clbanning/mxj

xmlBytes = []byte("<DOC>...</DOC>")
xmlStruct, err := mxj.NewMapXml(xmlBytes)
if err != nil {
  // handle error
}
theTag, err := xmlStruct.ValuesForPath("DOC.SubGroup2.TheTag")
if err != nil {
  // Do not exist "TheTag"
}
theTagInterface := theTag.(map[string]interface{})
myTagAttr := theTagInterface["-MyTagAttr"].(string)

val4, err := xmlStruct.ValuesForPath("DOC.SubGroup2.TheTag.Value4")
if err != nil {
  // Do not exist "Value4"
}
theVal4Interface := val4.(map[string]interface{})
myVal4Attr := theVal4Interface["-MyTagAttr"].(string)

answered Feb 9, 2023 at 5:03

Alexandr Kamenev

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