Creating your own grails plugin and eating your own dog food

So as you may have seen in my last few posts. I spent most of the weekend creating my first grails plugin. My lovely wife is away for 3 weeks on holiday so I am blasting out all the little projects that I have wanted to do.

So I thought I would just write a little piece about my experience of writing the plugin. First thing i would like to say is what a pleasure it was to write and as how easy it was. So how did it come about.

Well I have been building my own application in grails for the last few months and one thing I really missed was client side javascript. I was quite suprised to find that there was no direct support for this in grails. In my day job we use the valang library that has greate support for generating client side javascript so I had gotten used to it. One thing I did find was this disbandond tag lib that sits in the grails core validate tag. So i looked at the source code for this tag and figured out what is was trying todo. It turns out that is was using the javascript support of the commons validation libarary.

So after some experimentation I realised I could resurect this and put it together as plugin to support client side javascript. So after some complicated things like getting access to the constraints object of command objects and generating i18n messages for the errors I finally put together the plugin in 4 releases over a weekend.

So things i found hard to do and never really managed to do it in a nice way was to mock out the grailsattributes object and grails application etc. My tag needs these to get access to domain and command objects but it is very complicated to mock them out.

Eating your own dog food.

So before i actually realeased the plugin i installed it in my own application and started using it in a real app. This turned out to be essential for testing. I found several issues that it did not handle. Things like: grails auto generating nullable constraints for all attributes of a domain class but not for command objects was tricky as you ended up with unecessary validation generated. So after a few rounds of tuning and robusting i realesed it.

Grails plugin release process.
It is so easy to release and re-release a grails plugin that you have to create one just to see that work. Auto tagging and versioning is handled so smoothly. But i guess i would not expect anything less from grails.

So to conclude if you have any greate ideas for a plugin then build them. There is nothing stopping you.

Remember someone once said that the saddest words of tongue or pen are these: "it might have been".

Ps. Version 0.4 is out now :)

Enjoy