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decode as object is the default

format/xml/xml.md

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XML can be decoded and encoded into jq values in two ways, elements as object or array. Which variant to use depends a bit what you want to do. The object variant might be easier to query for a specific value but array might be easier to use to generate xml or to query after all elements of some kind etc.

Encoding is done using the to_xml function and it will figure what variant that is used based on the input value. Is has two optional options indent and attribute_prefix.

Elements as object

Element can have different shapes depending on body text, attributes and children:

  • <a key="value">text</a> is {"a":{"#text":"text","@key":"value"}}, has text (#text) and attributes (@key)
  • <a>text</a> is {"a":"text"}
  • <a><b>text</b></a> is {"a":{"b":"text"}} one child with only text and no attributes
  • <a><b/><b>text</b></a> is {"a":{"b":["","text"]}} two children with same name end up in an array
  • <a><b/><b key="value">text</b></a> is {"a":{"b":["",{"#text":"text","@key":"value"}]}}

If there is #seq attribute it encodes the child element order. Use -o seq=true to include sequence number when decoding, otherwise order might be lost.

sh
# decode as object is the default
$ echo '<a><b/><b>bbb</b><c attr="value">ccc</c></a>' | fq -d xml -o seq=true
{
  "a": {
    "b": [
      {
        "#seq": 0
      },
      {
        "#seq": 1,
        "#text": "bbb"
      }
    ],
    "c": {
      "#seq": 2,
      "#text": "ccc",
      "@attr": "value"
    }
  }
}

# access text of the <c> element
$ echo '<a><b/><b>bbb</b><c attr="value">ccc</c></a>' | fq '.a.c["#text"]'
"ccc"

# decode to object and encode to xml
$ echo '<a><b/><b>bbb</b><c attr="value">ccc</c></a>' | fq -r -d xml -o seq=true 'to_xml({indent:2})'
<a>
  <b></b>
  <b>bbb</b>
  <c attr="value">ccc</c>
</a>

Elements as array

Elements are arrays of the shape ["#text": "body text", "attr_name", {key: "attr value"}|null, [<child element>, ...]].

sh
# decode as array
$ echo '<a><b/><b>bbb</b><c attr="value">ccc</c></a>' | fq -d xml -o array=true
[
  "a",
  null,
  [
    [
      "b",
      null,
      []
    ],
    [
      "b",
      {
        "#text": "bbb"
      },
      []
    ],
    [
      "c",
      {
        "#text": "ccc",
        "attr": "value"
      },
      []
    ]
  ]
]

# decode to array and encode to xml
$ echo '<a><b/><b>bbb</b><c attr="value">ccc</c></a>' | fq -r -d xml -o array=true -o seq=true 'to_xml({indent:2})'
<a>
  <b></b>
  <b>bbb</b>
  <c attr="value">ccc</c>
</a>

# access text of the <c> element, the object variant above is probably easier to use
$ echo '<a><b/><b>bbb</b><c attr="value">ccc</c></a>' | fq -o array=true '.[2][2][1]["#text"]'
"ccc"

References