Generate error when attempting to use filter on objects

[justincy]

Currently it fails silently if you try to use filter on objects, as in the example below, because it only supports arrays.

<div ng-repeat="item in object | filter:{display:true}">stuff</div>

I blew a ton of time on this because it's not very intuitive since ng-repeat supports objects. I fully expect to make the same mistake again. A simple error message would save a world of hurt.

[BrianMinister]

I am concerned that if angular performs an is array check on every ng-repeat directive, one of the slowest directives in angular may get notably slower on more complex dashboard applications like mine where I have 2 or 3 layers of nested ng-repeats.

[caitp]

I am concerned that if angular performs an is array check on every ng-repeat directive, one of the slowest directives in angular may get notably slower on more complex dashboard applications like mine where I have 2 or 3 layers of nested ng-repeats.

this is not likely to matter at all --- it's a one-time operation and it's a very small slice of the time (per set, as opposed to per item) taken to process that array in the first place. Even for nested repeats, the work isn't going to grow exponentially, it's really not going to matter

[caitp]

@justincy would you be interested in sending a PR for this? it should be a pretty trivial 1 line fix + a test case

[justincy]

@caitp I am interested but I've never looked at the angular.js source code so I can't promise anything.

[caitp]

If I'm not mistaken, it's basically this:

function filterFilter() {
  return function(array, expression, comparator) {
-   if (!isArray(array)) return array;
+   if (!isArray(array)) throw $minErr('filter')('notarray', 'expected Array but received {0}'', array);

    var comparatorType = typeof(comparator),
        predicates = [];

(and then you'd need to make up a 'notarray' error document in docs/content/error/filter/notarray.ngdoc --- but its not hard.

[caitp]

then again, I guess this would be a breaking change, so really you'd just want to log it --- even simpler

[caitp]

(oops, too much coffee)