Just a very quick look at a new feature in v2009 vol 2 of XAF. This is very early stuff, I hear the beta won't be along before the end of June.
We have added the ability to apply rules to collection properties. For instance, in this screenshot you can see a rule failing that is defined to check against the sum of values over the collection. The values in the field "Sum between 0 and 50" are supposed to add up to 50 at most, but since the sum is actually 60, the rule triggers a validation error.
Here's another example. In the "lowest" of the three stacked windows, you can see a collection of objects with a field called "Item Unique Value". The rule that is applied to the collection checks whether the field values are unique across the entire collection. When the detail view is brought up and the second item is edited to have the same value in that field as the first object, the rule triggers a validation error.
