TFS Work Item - Allow transition to state only if System.AttachedFileCount > 0

Question

Is it possible to do without having to create a custom control?

I need to allow the change of state of a custom work item only if it has at least one file attached. System.AttachedFileCount field of Attachments Control doesn't support "REQUIRED": I would like to use it as a condition for a transition.

I am trying to figure it out by adding one custom Field used only to copy in the value present in System.AttachedCount.
I set the rule "COPY" in the custom field in order to copy in the number of attachments of the work item. Then I can check the value of the custom field in the transition or state using the rule "PROHIBITEDVALUES" = 0. This could be a workaround, but the problem is that it cannot work inside the same state: If I edit the work item without changing the state and add some attachments, the value of the custom field does not change.

Are there is some other rules to try?

Answer 1

Ok, I found a way.

I added a new custom field, integer type. No rules. On the GUI, I added just above the Attachment Control a Fild control referenced to my new custom field. At a first transition, I set the field with rule "EMPTY". At a first state, I added to the field the following rules: - "COPY": copy from field System.AttachedFileCount - "WHENCHANGED": check if the field System.AttachedFileCount changes and as rule I set "EMPTY" - "PROHIBITEDVALUES": set che value "0", so counter = 0 is not allowed (but EMPTY is Allowed!).

when I try to save the workItem at the first state i gives the error indicating that 0 is a prohibited value, so I need to attach at least one file.. IT WORKS!!

L.