ADD sorting in views by nested (related) fields ?

[mcd-php]

For ArrayDataProvider, i already did this by overriding ArrayHelper::getValue to make it recursive and trivially overriding ArrayDataProvider::sortModels to use it ( hey, dependency injection, where you are ? )

For ActiveDataProvider, this will imply joins and extraction of join criterias from relations. But why not ?

P.S. In nested relations, dot is used as separator. However, in sort it doesn't get through, so i was forced to use -> as separator. Where is the dot being rejected and how to fix it ?

\yii\data\Sort::$separators should be changed to anything not related to class-field separation in any reasonable programming language, maybe ['~','-'] ? Separate issue ?

P.S.2 Do you need \app\data\LazyRelationsArrayDataProvider i just created for populating relations only on models to be shown ?

[cebe]

related to #802