CODEWITHSUNDEEP
firebase
Paulo P. Marinas
Paulo P. Marinas

Reputation: 43

Change limitToLast dynamically

I have an app that can load more items when user scrolled at the bottom, I'm thinking one way to handle this is to adjust limitToLast dynamically so the child_added event will get triggered again.

Can I do this without having to rebind my .on() functions?

Upvotes: 1

Views: 1110

Answers (2)

sublok
sublok

Reputation: 1

function doDynamic(offset){
    ref.orderByChild("foo").limitToLast(1 * offset).once('value', function (snap) {
        //do stuff
    })
}

Upvotes: 0

Frank van Puffelen
Frank van Puffelen

Reputation: 599686

If you have a query like this:

var query = ref.orderByKey().limitToLast(10)

And you want to change the number of items shown, you will have to create a new query:

var query = ref.orderByKey().limitToLast(25)

However: if you're just looking to pick up new items that are added to Firebase, that will happen automatically.

An example may clarify this. Say that you start with a list of 10 items:

-Jy39378901
-Jy39378902
-Jy39378903
-Jy39378904
-Jy39378905
-Jy39378906
-Jy39378907
-Jy39378908
-Jy39378909
-Jy39378910

With the first query above, you will initially get 10 child_added events.

Now if someone later adds an item -Jy39378911 to this list, you will get two events:

child_removed: -Jy39378900
child_added  : -Jy39378910

So new items show up automatically. But changing the query parameters is not possible, unless you create a new query.

Upvotes: 1

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