Annyce Davis

Davis Technology Consulting

Using Grails’ JSON and HTML Builders

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In order to generate JSON in groovy that can then be passed to a Grails controller you should use the JSONBuilder class. This class is part of the Grails util package. The code below demonstrates how to generate JSON and HTML.

Resulting JSON that is produced:

ResultSet {['text':'google', 'url':'http://www.google.com'], ...}

def writer = new StringWriter();
new grails.util.JSonBuilder(writer).json {
  ResultSet {
    links.each { link ->
      Links(text: link.text, url: link.url)
    }
  }
}
writer.toString()

This is the code to do the same with HTML, you would use the Groovy XML MarkupBuilder instead.


StringWriter w = new StringWriter()
def builder = new groovy.xml.MarkupBuilder(w)

builder.div (class: 'className'){
  links.each { link ->
    p {
      b 'Title: '
      builder.yield link.text
    }
  }
}
w.toString()

Resulting HTML that is produced:
<div class=”className”>
<p><b>Title: </b>google</p>
</div>

Deploying a Grails Application to Production

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Beware of a weird grails config option!

To create a war file that can be deployed to a web server you would use grails war file_name.war, however this by default includes any plugins (so it seems) that you have installed with the application that you would not necessarily want deployed and can cause serious issues when deployed to your web server. So the fix is to use grails prod war file_name.war and the plugins are not included.

Unix History Command

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In order to save myself from painstakingly typing the same commands over and over again I invested a little time in learning about the Unix history command. One workflow that I have found very useful is the following:

!vi – repeats the last vi command that I typed (apply this to any command)
!! – repeats the last command that I typed

history – prints out the entire history with the associated number for each command
example:
100 – vi info.txt
101 – mv info.txt noinfo.txt

history > myhistory.txt – this will store the contents of my history in a file for later reference

Using the information derived from history I can then do the following:
!100 – this will perform the command vi info.txt
more !:$ – this will take the first argument of the last command and perform a new command on it. So in this instance I will essentially have more info.txt.

Amazing stuff, hunh!

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