Cloud Firestore exception handling

Question

My flutter app is using firestore. In the firestore collection 'members' I am restricting adding new documents having the same mobileNo using a security rule

match /members/{mobileNo} {
      allow create: if !exists(/databases/$(database)/documents/members/$(mobileNo))
    }

I am putting the dart code in a try catch block like so

try {
    await members.doc().set({
                'id': members.doc().id,
                'name': name,
                'mobileNo': mobileNo,
                'address': address,

              });
    } catch (e) {
MyMessageHandler.showSnackBar(_scaffoldKey, 'number already registered!');
    }

so I can catch the exception and provide an error message. Instead of the generic catch(e), I want to catch a specific exception using on SpecificFireStoreException catch(e) clause and deal with it. But I don't know the type of exceptions thrown by the security rules by firestore so as to code like the FirebaseAuthException

}on FirebaseAuthException catch(e) {
 if (e.code = 'weak-password'){
MyMessageHandler.showSnackBar(_scaffoldKey, 'Weak password!!');
}

I want to do something similar but with the exception given by the security rule. Thanks for the help.

Answer 1

Cloud Firestore throws a variety of exceptions depending on the operation and the specific error encountered. However, you can catch exceptions related to security rules using the FirebaseFirestoreException class.

The FirebaseFirestoreException class has the following properties:

• code: a string that represents the error code.
• message: a string that describes the error message.
• details: a list of strings that contains additional details about the error.

Here's an example of how you can catch FirebaseFirestoreException in your code:

try {
  await members.doc().set({
    'id': members.doc().id,
    'name': name,
    'mobileNo': mobileNo,
    'address': address,
  });
} on FirebaseFirestoreException catch (e) {
  if (e.code == 'permission-denied') {
    MyMessageHandler.showSnackBar(_scaffoldKey, 'You do not have permission to perform this action.');
  } else if (e.code == 'already-exists') {
    MyMessageHandler.showSnackBar(_scaffoldKey, 'Number already registered!');
  } else {
    MyMessageHandler.showSnackBar(_scaffoldKey, 'An error occurred: ${e.message}');
  }
}

In this example, you can catch FirebaseFirestoreException using the on keyword and the catch clause. You can then access the code property of the exception to determine the type of error and provide an appropriate error message.

Note that the specific error codes that Firestore throws can change over time, so you should consult the Firestore documentation to ensure that you are using the correct codes for your use case.