CODEWITHSUNDEEP
firebase
martypdx
martypdx

Reputation: 3712

Firebase data consistency across multiple nodes

According to the firebase docs data is flattened and indices are used to link different nodes in the tree:

users
  $userId
    widgets
      $widgetId
widgets
  $widgetId

In the above example, if a user creates a widget, that widgetid is also stored under the user node.

My question is whether there is a way to guarantee the consistency of the operation, considering there is now the more than one write required.

Assuming the first operation is:

var newKey = fb.child('widgets').push({ name: 'widge' }).key();

I can then write it to:

fb.child('users').child(auth.id).child('widgets').child(newKey).set(true);

But what if there was a failure or other problem between the two writes? Or if I have multiple places I need to store that key and a failure occurs between those writes?

Is there currently a way to handle this in firebase?

If not, are there plans to support this in the future?

And if so, can someone provide a specific example of how that would be done?

Upvotes: 4

Views: 1667

Answers (2)

Kato
Kato

Reputation: 40582

Note that this is now part of the core Firebase API. See this blog post for details.

var mergedUpdate = {};
mergedUpdate[ 'users/' + userId + '/widgets/' + widgetId ] = true;
mergedUpdate[ 'widgets/' + widgetId ] = widgetData;

var ref = new Firebase("https://<YOUR-FIREBASE-APP>.firebaseio.com/");
ref.update(mergedUpdate);

Upvotes: 2

Saeed D.
Saeed D.

Reputation: 1176

Take a look at transaction operation and utilize onComplete callback to make your second write. You can chain the transactions.
The examples provided on Firebase site are for incrementing counters safely.

I have provided a sample code for another question that may be of help to you. How to store users and groups for a chat using Firebase

Upvotes: 0

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