I have a power pages implementation associated with D365, I have implemented some duplicate detection rules:
https://learn.microsoft.com/en-us/power-platform/admin/set-up-duplicate-detection-rules-keep-data-clean
However those only works in the CRM, how I can prevent the web portal user create a duplicate record? like a post or a contact? I’m using a basic form for create new records.
Write a custom duplicate detection rule under addOnSave that runs before the duplicate record is saved and validates the entry. Add a custom XML here to find the duplicate and perform necessary actions.
You may also consider registering a preimage plugin to stop duplicate record creation. You may also perform post creation validation and deactivation.