In a workflow where fields entered in a registration form are concatenated to create a unique ID (IE municipal and district IDs, date of birth, first two digits of first and last name, etc) and saved, is there a way to check the saved ID case property against the other existing IDs of the other cases to ensure you're not creating an identical ID? 
Checking unique case property (saving an ID) against already-saved case properties of other cases
commcare
I don't think there is a way to actively check (especially given the offline functionality). The best design solution I can think of is:The domain must be on the Standard Plan for User as a Case to be availableAdd custom user data number for each mobile worker (e.g. mobile user 1 = 01, mobile user 2 = 02)Add a counter that would increment for each case registered by each mobile workerAdd the custom user data+counter number to each of the UIDs for the cases (e.g. the first case registered by mobile user 1 would be 011 = user case property + counter number) 