Making Grails data-binding interpret empty String values ("") as zero (0)

Question

This question is about altering how the Grails data-binding handles string-to-integer conversion.

Consider the following domain object:

class Foo {
  String name
  Integer price
}

Furthermore, assume that the domain object is populated from HTTP request parameters:

def foo = new Foo(params).save()

The save() method above will fail if params.price == "" (empty string). I'd like to change this behaviour globally so that an empty string is parsed as zero (0) when converting from a string to an integer in Grails data-binding. How do I achieve that?

Answer 1

Instead of changing the data binding why not just write your own setter? In the setter test to see if the string is empty, if it is set price to 0. If it isn't do a normal integer conversion.

Answer 2

added a filter see the setion 5.5.1 Events and Auto Timestamping in the grails documentation (http://grails.org/doc/1.1.x/index.html)

   def beforeInsert = {
       if (price == '') { price = 0}
   }

Answer 3

try this constraint instead

static constraints = {
    price(validator: {val, obj ->
        if (val == '' || val == 0) {
            obj.price = 0
            return true
        } else if (val < 1) {
            return false;
        }
    })
}