Tech Beats

Now that I decided to organize and publish some of my code/hacks here, I thought it would be a good thing to republish here my Grails caller script.

I work and mantain various Grails projects at the same time, and some of them uses versions of Grails as old as 1.0.3! So the question is: How to call the right version of grails command for a given project, the version that the project was created with?

First I tried changing the GRAILS_HOME environment variable every time I was going to work with a project that uses a different version than the default. But it’s just too much work for a thing that should be transparent. So I decided to create a shell script to solve this problem. The script should detect which Grails version to call when it’s executed. Here’s the script I came up with:

How it Works?

The script first checks if you specified a version in the command line, like: grails 1.3.5-SNAPSHOT create-app. If not, it looks for an application.properties file in the current folder. This file keeps some metadata for Grails' projects, including the Grails version the project was created with. If it does not find any application.properties in the current folder, it then just calls the default Grails installed in your system, the one that GRAILS_HOME points to.

Prerequisites

• All your Grails versions must be installed under the same base directory. Ex:

  /opt/grails-1.0.3
    /opt/grails-1.1.1
    /opt/grails-1.2-M2
    /opt/grails-1.3.3
    /opt/grails-1.3.5-SNAPSHOT

• GRAILS_HOME environment variable must be set and point to your “default” Grails installation

• This script was tested on Mac OS X (Snow Leopard), Linux (Ubuntu) and Windows (with cygwin)

Installation

• Download the script: http://gist.github.com/601039
• Include the folder where it is installed in your PATH.
• Exclude $GRAILS_HOME/bin from your PATH

Usage

Using the script is as transparent as possible:

• If you invoke it from a project folder, it will detect the version used by the project and call the correct grails (if it is installed in your system)
• If you invoke it from any other folder that does not contain a Grails project, it will call the “default” Grails installation

• If you want to call a specific Grails version (i.e. when doing an upgrade) you can specify the version you want in the first parameter. Ex:

  $ grails 1.3.3 upgrade

If you have any question or suggestion, please leave a comment here or send it to the Grails user list.