Combo Box vaildation

hey there,, 

i have a combox show all rooms in the database that i had created it ,, so i need to make something when the user make a new booking the combo box show only the available room ..


Remember those Widget I or Widget II online courses.

Combo Box have 2 source, you need to choose 1:

1. Source Entity ==> directly from entity, cannot have custom filter (but may filter your IsActive attribute if specified)

2. Source Record List ===> accept any List, including Aggregate List in your Preparation Logic, or List in your Local Variable.

If you want customization for combobox, use option 2.

To enable Source Record List option, you need to pick None in Source Entity option.

thank you very mush for replaying , but how i customization the list ? if i have a room entity and booking entity and they have a relationship 

Create aggregate in Preparation Logic.

Aggregate can join entities.

Use Aggregate's List in combobox.