javascript - How to delete a specific child from a child in Firebase

Question

I have an application where a user can create lists.

The user can share a list with other users. I already manage to create the sharing part, the one I'm having issues is with the delete part. I want that when a user deletes a list that is shared , this list is also deleted from the other users.

This delete will be made only by list owner.

So a scenario will be:

• User A creates a List with pushID = 1.
• This list is added in the following firebase ref: /userList/$userAID/$pushID.
• User A shares list with User B and User C.
• This list is added in the following firebase ref: /userList/$userBID/$pushID and /userList/$userCID/$pushID.
• User A deletes list with pushID = 1.

So in my

So i have this schema:

userList: {
   2xYnKcZFEdPYWfUJ3E63yQEDShe2: {
     -Kt7lXiY0Yt-oDcV38L5
   }
   KtQHkXMSwKSByZ1rmTRwjDmSYnE3: {
     -Kt7lXiY0Yt-oDcV38L5: {}
     -Kt9XP91hjwcwgcBSgbc: {}
   }
   XHpMVoRqcCdzwTP70L29Lza1ibD3: {
     -Kt7lXiY0Yt-oDcV38L5: {}
   }
}

In high level this will be:

userList: {
       userID: (A) {
         -listID : (1) {}
       }
       userID: (B) {
         -listID: (1) {}
         -listID: (2) {}
       }
       userID: (C) {
         -listID: (1) {}
         -listID: (3) {}
         -listID: (4) {}
       }
    }

The current code I have to do this is the following:

const ref = firebase.database().ref('userList');
    ref.once('value')
      .then((snapshot) => {
        snapshot.forEach((childSnapshot) => {
          ref.child(childSnapshot.key)
            .once('value')
            .then((snapshot2) => {
              snapshot2.forEach((childSnapshot2) => {
                if (childSnapshot2.key === uid) {
                  ref.child(childSnapshot2.key)
                    .remove();
                }
              });
            })
            .catch(() => {
              console.log('error2');
            });
        });
      })
      .catch((error) => {
        console.log(error);
      });

What I'm doing in this code is, first fetching ALL the list inside userList, by getting the key I manage to jump to the userID child. Inside this node once again I manage to jump inside the pushID where I make a validation of checking if current key is equal to the UID of the list i want to delete, if so I do a remove().

I feel there must be a better way of telling Firebase to go directly to pushID and find all of those that are equal to the UID of the list I want to delete and then do it.

Answer 1

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