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)

[IShotTheSheriff]

Hi, I would be also interested in this issue, as it seems like a good place to start contributing adventure ;). I've started to work on that, but I couldn't make the tests passes. Could I ask for one more tip about how to use logging inside your source files? I've done it like this:

filterFilter.$inject = ['$log'];
function filterFilter($log) {
  return function(array, expression, comparator) {
   if (!isArray(array)) { 
     $log.error(new Error('filter expcted array but received ' + typeof array))
     return array;
   };

I've tested the solution and I've added unit test and it passes. Unfortunately from ngMock unit tests I get error:

Expected $log to be empty! Either a message was logged unexpectedly, or an expected log message was not checked and removed.

If it wouldn't be a problem could you please point me gently to the right direction with this one?

[IgorMinar]

I think that we should throw, but because that's a breaking change we should schedule this for 1.4

[Puigcerber]

While creating this pull request I've noticed there are two protractor tests failing. The should auto compile for the example-example51 throws Expected 'name}}!' to be 'Angular!'. but is not related to these changes and fails for me as well in master. Could somebody try it out?

[mgcrea]

This type check broke promise usage with filters, the following expression is now throwing errors before resolving the promise:

getAddress($viewValue) | filter:"Al" | limitTo:6

  $scope.getAddress = function() {
    return $q(function(resolve, reject) {
      resolve(['Alabama', 'Alaska', ...]);
    });
  }

This broke AngularStrap typeahead with remote source example.

Is there another way to achieve this?
If not, I think we should revert this & remove the check/error (or at least allow promises).