Filtered lookup field

Question

I would like to apply filtering to existing out-of-the-box lookup fields (without InfoPath).

The solution should be limited to GUI only: when Backup/Restoring to a clean farm the filtering would be gone but all the data preserved and usable.

Answer 1

You might want to look at the jQuery library for SharePoint, SPServices. There is one operation, SPFilterDropdown, that allows you to filter a lookup column via CAML. Usage example from the documentation:

$().SPServices.SPFilterDropdown({
  relationshipList: "Countries",
  relationshipListColumn: "Title",
  columnName: "Country",
  CAMLQuery: "<Eq><FieldRef Name='Active' /><Value Type='Boolean'>1</Value></Eq>",
  completefunc: null,
  debug: false
});

I haven't used this particular operation, but the other aspects of the library are stellar.