I have a feeling I am going over old ground here but I have checked numerous posts and they aren't of a great deal of help for what I am trying to do.
I should say at the outset that the project is a change to an existing sharepoint site hence the design. I probably wouldn't do it this way if I was doing it from scratch.
I have two drop downs on a form, Category and Subcategory for a document information panel. We have projects that are broken down historically by categorys eg A1:, A2:, A3:, A4:, A5: (These mean something to our design teams and then subcategorys of A11, A12, A13, A14, A21, A22, A23, A24, A25 etc......... These have descriptions after them but for brevity I have left them off.
What I need to do is choose the category say A1 and have the subcategory dropdown filtered to A11, A12, A13, A14 only.
What I've done so far.
1) If I leave the main data connection, The correct data appears on the form but the filter wont work. In fact I cant even add a filter as I need to select "lookup values from this forms data source" on the data tab on the drop down lists properties. When you try to do that an point it to the correct field it basically says "You have selected a fieldd where the control saves data. Instead, select a field where the control looks up data".
2) If I add a secondary data connection, my filter (namely - Subcategory begins with substring-before(Category,":") works perfectly except that it seems to query the metadata on the items in the list rather than the properties on the main data source. This means not all the possible Subcategorys appear, only the ones that exist already on documents in the document library. To be clear, Assume there are 30 different subcategorys and there are 3 documents in the library at the moment. When I set it up as per 2) I would get only the 3 subcategorys that are on the documents in the library.
I have tried many other work around but I am getting nowhere. Does anyone have any ideas as to how I could accomplish this or can anyone direct me to helpful information. I have scoured the web for a few days now and this is slowly making me suicidal.
Any help would be greatly appreciated .
Best wishes,
Gav