Grails internals : Auto mapping and Domain object creation

Question

Hello, I am trying to make a taglib to represent an object (to read and display at the UI). When creating an object (save method in the controller), I see the domain class and association are created by the auto assignment of parameter

def Book = new Book(params) 

It also maps complex types (for eg: joda time). I wonder about the naming convention necessary to facilitate this mapping. Out of curiosity, can someone also point where in the grails source code I could see how grails handles this mapping. I'm still learning Spring and probably this would be a good exercise. Thanks, Babu.

Answer 1

AFAIK the naming conventions are rather straightforward. If there's a field params.foo and the object you are binding to has a field foo, it will bind the value, assuming the type conversion works properly. If there's a params.bar.id set with an Long value and your object has a complex property of type Bar, it will lookup this instance and inject it.

If you need more control over the binding process, you might want to use bindData.

If you are interested into the details of the binding process, have a look at Java's PropertyEditor as this is what is being used in the background. I wrote a blog post on how to create and register PropertyEditors a while ago, maybe it helps you getting started with that stuff.