Restrict duplicate phone numbers

[mahalakshme]

Need:

• Restrict duplicate phone numbers to 5. If two farmers have the same name, then don't count them as duplicates

Suggested technical approach:

• Add a custom query that returns the no of individuals with same phone number but different first name and last name than the ones in the request. For farmers with same name and same mobile numbers should not be counted as 2.
• Make validation rule async(for now mobile app alone) - refer this
• From the mobile app validation rule, call /executeQuery api and show the error stating 'Number of times this mobile number can be used has exceeded than the allowed limit' if the number of duplicate mobile numbers with different names exceed 5. This error message should be translatable. Suggest doing in form element or form element group rule unless we are sure it will cause performance issues.
• If API call doesn't go through, then show the error 'Switch on your internet connection.' This error message should be translatable.

Questions:

Why not form element rule or form element group rule we can do it in?