Exception when trying to delete a data file type that is referenced from item subtype

[Nicklas Nordborg]

We have an item subtype and a data file type. The item subtype has been configured with a reference to the data file type.

When trying to delete the data file type there is no indication that it is used in the trashcan. This results in the following exception:

update or delete on table "DataFileTypes" 
violates foreign key constraint "FKmnjqbi7ofj7k0bam7cyh5t3k5" 
on table "ItemSubtypeFileTypes"
Detail: Key (id)=(204867) is still referenced from table "ItemSubtypeFileTypes".

The workaround is to manually remove the link between the item subtype and the data file type. This is done from the item subtype edit dialog.

[Nicklas Nordborg]

UPDATE:

It should not be possible to delete the data file type without first removing the link. The traschcan should display the item subtype that is referencing the data file type.

[Nicklas Nordborg]

(In [7312]) Fixes #2065: Exception when trying to delete a data file type that is referenced from item subtype

The item subtype should now be displayed in the trashcan under the "Items using" section.