utils-xml2object

v2.0.2

Published

a year ago

Extract object from xml using xpath syntax

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stanbienaives

xml xpath

xml2Obj

xml2obj is a utility that convert a xml document in an object in regard to a given mapping

It uses the xpath syntax. Here is a helpfull cheatsheet

 const xml = "\
  <HEAD> \
    <TITLE>My title</TITLE> \
    <VERSION myattr='truc'> nothing </VERSION> \
  </HEAD>"

  const extractor = xml2Obj.extract(xml, {
    title: '/HEAD/TITLE/text()', // this will take the text content withing the tag TITLE
    attr: '/HEAD/VERSION/@myattr' // This will take the attribute "attr" attached to the VERSION tag,
  }

  // {title: 'My title', attr: 'truc'}

Extract html

When html is embedded within the html you have to specify it

const extractor = xml2Obj.extract(xml, {
  content: {
    path: '/HEAD/TITLE' // this will capture every thing withing the Title Element stripping out the TITLE tag
    isHtml: true,
  },
  attr: '/HEAD/VERSION/@myattr',
}

Extract nested object

Sometime it is handy to create an array or a nested object from a group of keys You can do that using the syntax below

const xml = "\
  <HEAD> \
    <TITLE>My title</TITLE> \
    <VERSIONS> \
       <VERSION num='v1'> \
          <ELEM myattr='this is v1'>v1text</ELEM> \
      </VERSION> \
       <VERSION num='v2'> \
          <ELEM myattr='this is v2'>v2text</ELEM> \
      </VERSION> \
    </VERSIONS> \
  </HEAD>"

  const extractor = xml2Obj.extract(xml, {
    myarray: {
      path: '/HEAD/VERSIONS/VERSION',
      mapping: {
        num: '/@num', // the num attribute of every VERSION 
        text: '/ELEM/text()', //The inner Text within all the ELEM tag in the VERSIONS
        attr: '/ELEM/@myattr', //You get it... 
      }
    }
  })

  //returns   { myarray: [{num: 'v1', text: 'v1text', attr: 'this is v1'}, {num: 'v2', text: 'v2text', attr: 'this is v2'}]

Check the tests for more examples

Strict Mode

By default all missing throws an error If you want to deactivate this beaviour you can call the extract function with an tolerance parameter The missing keys wont appear in the resulting object

 xml2Obj.extract(xml, {...mapping}, {tolerant: true})

You can also set the tolerance at key level:

  const extractor = xml2Obj.extract(xml, {
    firstVersion: {
      path: '/HEAD/VERSIONS/VERSION[1]/@doesnotexists',
      tolerance: true,
    },
  }, { tolerance: false })

NOTE: if tolerance is set to true at the global level. Tolerance at key level has no effect.

Namespaces

Whenever namespaces are used in the document you should specify the name space useds and their ids in the options The namespaces and id are specified in the xmls document

  const xml = "\
  <HEAD> \
    <NS1:TITLE xmlns:NS1='NS1ID'> \
      <NS1:SUBTITLE>My Sub Title</NS1:SUBTITLE> \
    </NS1:TITLE> \
    <NS2:TITLE xmlns:NS2='NS2ID'> \
      <NS2:SUBTITLE>My Sub Title 2</NS2:SUBTITLE> \
    </NS2:TITLE> \
    <CONTENT> Content </CONTENT> \
  </HEAD>"

  const extractor = xml2Obj.extract(xml, {
    subtitle: '/HEAD/NS1:TITLE/NS1:SUBTITLE/text()',
    subtitle2: '/HEAD/NS2:TITLE/NS2:SUBTITLE/text()',
    content: '/HEAD/CONTENT/text()',
  }, {namespaces: {
      'NS1': 'NS1ID',
      'NS2': 'NS2ID',
    }})

  // returns { subtitle: 'My Sub Title, subtitle2: My Sub title 2 , content: 'Content'}

Apply function to results

It is possible to apply a function to the result a the key level using the function apply

  const xml = "\
  <HEAD> \
    <TITLE>My title; garbage</TITLE> \
    <VERSION myattr='truc'> nothing </VERSION> \
  </HEAD>"

  const extractor = xml2Obj.extract(xml, {
    title: {
      path: '/HEAD/TITLE/text()',
      apply: (title) => title.split(';')[0],
    },
    attr: '/HEAD/VERSION/@myattr',
  })

Set default to key

You can set a default value to keys using the syntax below:

  const extractor = xml2Obj.extract(xml, {
    title: {
      path: '/HEAD/TITLE/text()',
      default: 'value if missing',
    },
  }, {tolerance: true})

Extract trees

Tree extraction can be done specifiying the name of the recursive node the _childrens key will be added when any child is found:

NOTE: The apply function cannot be used along with tree

  const xml = "<HEAD> \
    <TITLE>My title</TITLE> \
    <NAV> \
      <ITEM num='1' name='parent'> \
        <ITEM num='11' name='child'> \
          <ITEM num='111' name='child'> </ITEM> \
        </ITEM> \
      </ITEM> \
      <ITEM num='2' name='parent'> \
        <ITEM num='21' name='child'> </ITEM> \
        <ITEM num='22' name='child'> </ITEM> \
      </ITEM> \
    </NAV> \
  </HEAD>"

  const extractor = xml2Obj.extract(xml, {
    docs: {
      path: "//HEAD/NAV/ITEM",
      tree: 'ITEM',
      tolerance: true,
      mapping: {
        num: '/@num',
        name: '/@name',
      }
    }
  }

TEST

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