Quick XML to/from JSON conversion

At a first glance XML and JSON have some similiarities but XML is actually document oriented while JSON is data-oriented. Nevertheless for some cases, specially when processing in Javascript, it's useful to convert XML into JSON and JSON into XML. Let's check some basic examples.

Simple example XML to JSON

Consider the following example:

<orders>
    <orderId type="normal">1234</orderId>
    <items>
        <item>
            <id>1234</id>
            <qty>1</qty>
        </item>
        <item>
            <id>5678</id>
            <qty>2</qty>
        </item>
    <items>
</orders>

To simply convert it to JSON in OpenAF just execute:

> af.fromXML2Obj("<orders>\n\t<orderId type=\"normal\">1234</orderId>\n\t<items>\n\t\t<item>\n\t\t\t<id>1234</id>\n\t\t\t<qty>1</qty>\n\t\t</item>\n\t\t<item>\n\t\t\t<id>5678</id>\n\t\t\t<qty
>2</qty>\n\t\t</item>\n\t</items>\n</orders>")
{
  "orders": {
    "orderId": "1234",
    "items": {
      "item": [
        {
          "id": "1234",
          "qty": "1"
        },
        {
          "id": "5678",
          "qty": "2"
        }
      ]
    }
  }
}

The result is pretty much similar to the original XML with just one small detail: the orderId's type attribute. It's missing from the final JSON object because JSON doesn't have "an array of attributes per key".

But there is a workaround:

> af.fromXML2Obj("<orders>\n\t<orderId type='normal'>1234</orderId>\n\t<items>\n\t\t<item>\n\t\t\t<id>1234</id>\n\t\t\t<qty>1</qty>\n\t\t</item>\n\t\t<item>\n\t\t\t<id>5678</id>\n\t\t\t<qty>2</qty>\n\t\t</item>\n\t</items>\n</orders>", ["orderId"])
{
  "orders": {
    "orderId": {
      "_type": "normal",
      "_": "1234"
    },
    "items": {
      "item": [
        {
          "id": "1234",
          "qty": "1"
        },
        {
          "id": "5678",
          "qty": "2"
        }
      ]
    }
  }
}

The last optional argument of af.fromXML2Obj is actually an array of keys meaning that if the XML tag name is found on the XML OpenAF will make it a map with keys prefixed with "_".

In this case, "_" is the XML tag associated value (e.g. 1234) and "_type" is the tag attribute type with its corresponding value (e.g. "normal").

Simple example JSON to XML

The reverse of the previous example is also possible:

> var obj = af.fromXML2Obj("<orders>\n\t<orderId type='normal'>1234</orderId>\n\t<items>\n\t\t<item>\n\t\t\t<id>1234</id>\n\t\t\t<qty>1</qty>\n\t\t</item>\n\t\t<item>\n\t\t\t<id>5678</id>\n\t\t\t<qty>2</qty>\n\t\t</item>\n\t</items>\n</orders>");
> af.fromObj2XML(obj);
<orders><orderId>1234</orderId><items><item><id>1234</id><qty>1</qty></item><item><id>5678</id><qty>2</qty></item></items></orders>

Note: Keep in mind that af.fromXML2Obj and af.fromObj2XML are just "simplifiers" to handle XML/JSON conversion. For full support of XML you should use OpenAF's XML plugin.

RSS example

One pratical use for these functions is the hability to easily convert RSS feeds into JSON and JSON into a RSS feed:

> mapArray(af.fromXML2Obj($rest().get("http://feeds.reuters.com/reuters/technologyNews")).rss.channel.item, ["title", "pubDate"])
[
  {
    "title": "Apple says Uighurs targeted in iPhone attack but disputes Google findings",
    "pubDate": "Fri, 06 Sep 2019 20:14:45 -0400"
  },
  {
    "title": "U.S. states launch antitrust probes of tech companies, focus on Facebook, Google",
    "pubDate": "Fri, 06 Sep 2019 18:05:56 -0400"
  },
  {
    "title": "Alphabet says received civil investigative demand from U.S. DoJ",
    "pubDate": "Fri, 06 Sep 2019 17:28:58 -0400"
  },
  {
[...]