feat(firestore): set to Firestore only when parameter is unique

[towfiqi]

Does the library has any builtin function to check for unique field fore firestore profile field? apprantly its not possible to make a document field value unique with firestore.

What is the current behavior?

I am trying to implement a this on signup form submit. I am trying this way, but I am getting firestore is not a function

onformSubmit = () =>{
const db = this.props.firebase.firestore(); //same error with withFirestore and this.props.firestore(); 
const usersRootRef = db.collection('Users');
const inputUsername = getUsernameFromInput();
const query = usersRootRef.where('username', '==', inputUsername).get();

query.then((snapShot) => {
    const matches = snapShot.size();
    if(matches > 0) {
        // prompt the user to come up with something else
        console.log('username already taken');
    } else {
        // username unique
        console.log('username is unique');
    }).catch((error) => console.log(error.message));
});
}

What is the expected behavior?
should query the Users collection with where constrains.

[towfiqi]

Update: Did it with vanilla Firebase API .

But it would be great if firebase.firestore query was supported by the library.

[prescottprue]

@towfiqi Firestore queries are supported with firestoreConnect (which uses redux-firestore for state management).

The uniqueSet method that exist for RTDB is for uniquely setting based on key, not one of that values on the object itself. I am open to something like a uniqueParameterSet where you would specify which parameter the write would be unique for (in your case "username". Do you have thoughts on a name?

Also, you may already know this, but you can use the useFirestoreForProfile config option with react-redux-firebase to have it automatically handle profile as it does with RTDB.