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November 20, 2013

Grails Goodness: Pretty Print XML and JSON Output

If our Grails application renders XML or JSON output we can set configuration properties to enable pretty printing. This can be useful in for example in the development environment where we enable pretty printing and disable it for other environments. We set the configuration property grails.converters.default.pretty.print with the value true to enable pretty printing for both XML and JSON output. If we only want to pretty print XML we use the property grails.converters.xml.pretty.print and for JSON we use grails.converters.json.pretty.print.

First we look at the XML and JSON output when we don't enable pretty printing for a simple book resource:

<?xml version="1.0" encoding="UTF-8"?><book id="1"><isbn>0451169514</isbn><numberOfPages>1104</numberOfPages><title>It</title></book>
{"class":"com.mrhaki.grails.sample.Book","id":1,"isbn":"0451169514","numberOfPages":1104,"title":"It"}

Now we get the same book resource but with the following grails-app/conf/Config.groovy snippet:

...
environments {
    development {
        // Enable pretty print for JSON.
        //grails.converters.json.pretty.print = true

        // Enable pretty print for XML.
        //grails.converters.xml.pretty.print = true

        // Enable pretty print for JSON and XML.
        grails.converters.default.pretty.print = true
        ...
    }
}        
...

The following output shows how the representation is formatted nicely:

<?xml version="1.0" encoding="UTF-8"?>
<book id="1">
  <isbn>
    0451169514
  </isbn>
  <numberOfPages>
    1104
  </numberOfPages>
  <title>
    It
  </title>
</book>
{
  "class": "com.mrhaki.grails.sample.Book",
  "id": 1,
  "isbn": "0451169514",
  "numberOfPages": 1104,
  "title": "It"
}

Code written with Grails 2.3.2.