Ionic with Firestore and user session

Hi all, goodmorning,

Hope someone knows more of Firestore. I create an index but when data is inserted than every user see tha same data. What I want is that I want to see data only of the user.

The app can used with and without an account but is it somehow possible to use a sort off sessionid what comes with a phone that use the app?

Here what I insert now in de index of firestore:

 add(text) {

   const id = this.db.createId();

   return this.db.collection('todos').doc(id).set({

     id: id,

     text: text,

     complete: false,

     createdAt: firebase.firestore.FieldValue.serverTimestamp(),

     updatedAt: firebase.firestore.FieldValue.serverTimestamp()