How to update all children in Firebase?

Question

I'm try on firebase update all child on one level of tree. For example something like this:

firebase.child("auctions").child().update({a: true});

and this give me back error, because child is empty. Are there any way how update all children of auctions?

Answer 1

You don't need that empty .child() invocation.

What firebase.child("auctions").update({a: true}); is going to do is change /auctions/a/whatever to /auctions/a/true.

If you really want to "update all child on one level of tree" then .set might work better since it will replace all the data at the endpoint with the object you give it. So if you ran firebase.child("auctions").set({a: true}); then everything under /auctions will be replaced with {a: true}

If you didn't want to blast away everything under /auctions but instead you wanted to blast away everything under auctions/a you could do firebase.child("auctions/a").set(true);

There are multiple ways to accomplish what you need. I'm just not 100% sure what you actually are in need of.

Answer 2

You will need to loop over all children at some point. Here's one simple way to do this:

firebase.child("auctions").on('value', function(snapshot) {
    snapshot.ref().update({a: true}); // or snapshot.ref if you're in SDK 3.0 or higher
});

Alternatively you can first collect all updates and then send them to Firebase as one (potentially big) update statement:

var updates = {};
firebase.child("auctions").on('value', function(snapshot) {
    updates["auctions/"+snapshot.key+"/a"] = true;
});
snapshot.ref().update(updates);  // or snapshot.ref if you're in SDK 3.0 or higher

Both snippets accomplish the same, but the latter send a single command so is more resilient in the case of network failure.