Check uniqueness

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I believe this link explains your issue:

Executing `Collection.firstWhere().exists()` should return `true` or `false`

exists() does return true or false. But the return type of first() and firstWhere is a YourDocumentType | Null [image] The exists method only exists on Documents and “NullDocs”. exists() is used to check if a reference is in the database. A NullDoc are like a a pointer we know points at nothing because either it doesn’t exist or you don’t have permission to it. When you use .byId that method either returns a document or NullDoc, [image] A NullDoc is like a bad reference, but it has informa…

Basically, you could use either of these

let alreadyExists = theUser != null

or

let isUnique = User.by_name(${userData.username}).isEmpty()