Java – JSR 303 – validate multiple internal lists

I am using JSR 303 and have written many comments, so I am familiar with the process of obtaining custom constraints

I've just had a problem. I'm not sure if I can solve it gracefully The items here are for illustration! So I have a grandparent object with a list of children Each child has its own list of children (apparently grandsons of grandparents) You can use @ size to constrain the size of this list But I need to limit the total number of grandparents' children so that if I test my grandparents' example, their children will be limited to 50 grandchildren Strange examples, I know: -)

I started this method by creating a method in my grandparents, which only calculates all elements in the sublist of the grandparent sublist and adds a simple @ size annotation to it It feels a little ugly - this method is added just for some validation Isn't that the part that JSR should solve?

Or – create a custom comment like this:

@CustomListSize(listName="children.children",min=0,max=50)
Grandparent
    --> List<Child> children
        @Size(min=0,max=5)
        -->List<Child> children
    --> List<Object> list1
        -->List<Object> list2

I can obviously use reflection / propertydescriptor to get it and check the minimum / maximum value This sounds good, or I have a better method in JSR 303, which I missed This works, but requires more code, but is still not ideal

Finally, what if I want to do the same check for the number of entries in List2? I can't repeat customlistsize, so how do I do this - have an internal list?

thank you

Chris

Solution

I think a custom validator for your grandparents will be a good way

@InnerListSize(lists = {"list1",list2"},max=50)
class GrandParent{
   List list1;
   List list2;

}

Reflection can be used to get a list Once we have them, it's easy to calculate the overall size The validator class is not particularly complex