Question 118981 in Firebase Question posted in
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Firebase – Firestore rules for not existing documents

Below code works if I have collection (in this case suppliers)

function isNotRestrictedinSuppliers(){
  let value=3;
  let suppliers=get(/databases/$(database)/documents/users/$(request.auth.uid)/settings/suppliers);
  return suppliers.data.suppliers_array.size() < value;
  //return true;
}
 match /suppliers/{document=**}{        
    allow read,update, delete: if isSignedIn() && isValidUser();
    //above is the same like allow write;
    allow create: if isSignedIn() && isValidUser() && (isPremium() || isNotRestrictedinSuppliers());  
}
match /suppliers/{supplier}{        
    allow read,update, delete: if isSignedIn() && isValidUser();
    //above is the same like allow write;
    allow create: if isSignedIn() && isValidUser() && (isPremium() || isNotRestrictedinSuppliers());  
}

Unfortunately, if there is no collection "suppliers" it doesn’t work.
What I want to do is restrict creation of suppliers but create if no supplier exists

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2

Answers


  1. 0

    I think there is no way to read a collection in sercurity rules. This is what document says:

    The get() and exists() functions both expect fully specified document paths.

    But you can count documents with aggregation queries via client sdk.

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  2. 0

    Firebase Security Rules won’t allow users to create if/else conditions. So basically you need to create another function to check if supplier documents exist and return true if it doesn’t exist

    function notExists(){
  let suppliers=exists(/databases/$(database)/documents/users/$(request.auth.uid)/settings/suppliers);
  return !suppliers
}

    This would cost one additional read per security check

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