https://github.com/mislav/asbestos

Render JSON from your XML Builder templates
https://github.com/mislav/asbestos

Last synced: 2 months ago
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Render JSON from your XML Builder templates

• Host: GitHub
• URL: https://github.com/mislav/asbestos
• Owner: mislav
• License: mit
• Created: 2009-06-23T18:37:40.000Z (almost 16 years ago)
• Default Branch: master
• Last Pushed: 2009-12-20T11:27:25.000Z (over 15 years ago)
• Last Synced: 2025-04-15T17:11:48.919Z (2 months ago)
• Language: Ruby
• Size: 85 KB
• Stars: 7
• Watchers: 4
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.markdown
  • License: LICENSE

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README

        
Asbestos

========

Template handler for Rails that allows you to use

a subset of XML Builder markup to produce JSON.

Take, for instance, a common "show.xml.builder" template:

    xml.instruct!

    xml.category(:private => false) do

      xml.name @category.name

      xml.parent do

        xml.id @category.parent_id

        xml.name @category.parent.name

      end

    end

If you copied that to "show.json.asbestos", you would get:

    

    {"category": {

      "private": "false",

      "name": "Science & Technology",

      "parent": {

        "id": 1,

        "name": "Religion"

      }

    }}

But of course, you don't want to duplicate your builder template

in another file, so we'll handle this in the controller:

    def show

      respond_to do |wants|

        wants.xml

        wants.json {

          # takes the "show.xml.builder" template and renders it to JSON

          render_json_from_xml

        }

      end

    end

With this method there's no need for a special template file for JSON.

Asbestos is designed to use existing XML Builder templates.

How does it work?

-----------------

The `xml` variable in your normal builder templates is the XML Builder object.

When you call methods on this object, it turns that into XML nodes and appends

everything to a string, which is later returned as the result of rendering.

This plugin provides Asbestos::Builder, which tries to mimic the behavior

of the XML Builder while saving all the data to a big nested ruby hash.

In the end, `to_json` is called on it.

Aggregates and ignores (important!)

-----------------------------------

Problems start when you have Builder templates that render *collections*,

like in index actions:

    xml.instruct!

    for category in @categories

      xml.category do

        # ...

      end

    end

There is a ruby loop in there, so if there are multiple categories the resulting

JSON would have just one. This is because the same "category" field in the JSON

hash would keep getting re-written by the next iteration. Asbestos::Builder is,

unfortunately, not aware about any loops in your template code.

The solution is to indicate explicitly which keys you want aggregated:

    render_json_from_xml :aggregate => ['category']

Now, what would previously create a "category" key will get aggregated

under a "categories" array, instead:

    { "categories": [ ... ] }

Sometimes, most often with root elements, you want a key ignored.

You can specify which occurrences to ignore:

    render_json_from_xml :ignore => ['category']