Get length of an array returned by firebase

Question

The usual .length property of the array doesn't work on the arrays returned by firebase. Here is the console.log of the returned array:

0: Object
1: Object
2: Object
3: Object
4: Object
$$added: function () { [native code] }
$$error: function () { [native code] }
$$moved: function () { [native code] }
$$removed: function () { [native code] }
$$updated: function () { [native code] }
$add: function () { [native code] }
$destroy: function () { [native code] }
$getRecord: function () { [native code] }
$indexFor: function () { [native code] }
$inst: function () { [native code] }
$keyAt: function () { [native code] }
$loaded: function () { [native code] }
$remove: function () { [native code] }
$save: function () { [native code] }
$watch: function () { [native code] }
length: 5
__proto__: Array[0]
concat: function concat() { [native code] }
constructor: function Array() { [native code] }
every: function every() { [native code] }
filter: function filter() { [native code] }
findIndex: function (a){if(null==this)throw new TypeError("Array.prototype.find called on null or undefined");if("function"!=typeof a)throw new TypeError("predicate must be a function");for(var b,c=Object(this),d=c.length>>>0,e=arguments[1],f=0;d>f;f++)if(f in c&&(b=c[f],a.call(e,b,f,c)))return f;return-1}
forEach: function forEach() { [native code] }
indexOf: function indexOf() { [native code] }
join: function join() { [native code] }
lastIndexOf: function lastIndexOf() { [native code] }
length: 0
map: function map() { [native code] }
pop: function pop() { [native code] }
push: function push() { [native code] }
reduce: function reduce() { [native code] }
reduceRight: function reduceRight() { [native code] }
reverse: function reverse() { [native code] }
shift: function shift() { [native code] }
slice: function slice() { [native code] }
some: function some() { [native code] }
sort: function sort() { [native code] }
splice: function splice() { [native code] }
toLocaleString: function toLocaleString() { [native code] }
toString: function toString() { [native code] }
unshift: function unshift() { [native code] }

even the console.log length property shows 5 but for some reason calling the length property returns 0.

Edit:

The length property of the array is set to 5 but the length property of the proto is 0. The .length property returns the 0 value under the proto .

Please output your `$scope.Notes` to the console and show a snapshot of it, that would help — Fedaykin, Aug 16 '14 at 14:11
if it returns 0, it definitely is empty. Select isn't broken (http://pragmatictips.com/26) — xtofl, Aug 16 '14 at 14:12
Did you try official documentation? https://www.firebase.com/docs/web/libraries/angular/api.html#firebasearray — PSL, Aug 16 '14 at 14:18
@PSL yep I tried the official docs but I couldn't find anything useful there related to this issue. — Kash Pourdeilami, Aug 16 '14 at 14:45
@J.Wells He is using AngulareFire which is Firebase's realtime data sync library for AngularJS. — David East, Aug 16 '14 at 17:29
@Khashayar.P I understand it's an angular app, but there wasn't any angular code. Also - it would appear that it turned out to be a firebase thing. — J.Wells, Aug 17 '14 at 13:44

David East · Accepted Answer · 2014-08-16T17:45:39.027

21

Keep in mind that calling $asArray is an asynchronous action.

$scope.notes = $firebase(ref).$asArray();
console.log($scope.notes.length); // the data has not loaded yet

The reason why you're seeing a zero length in the console is because values can change between buffering of the log and printing it, which can be very misleading. Try using a breakpoint to see the values as they execute.

Since the data is asynchronous you'll need to use the $loaded promise.

$scope.notes.$loaded().then(function(notes) {
   console.log(notes.length); // data is loaded here
});

edited Aug 16 '14 at 17:45

answered Aug 16 '14 at 17:27

David East

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How can the length value displayed in the DOM? will it be updated every without adding watch ? – nabil Dec 28 '14 at 17:42
Thank you David for your help ) – Kas Elvirov Sep 19 '16 at 13:54

Get length of an array returned by firebase

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