angular filter empty array in an object

Question

I have this array of objects

var list = [{
    "questionId": 1,
    "correctChoiceIds": [],
    "choiceId": 0,
    "number": 1
}, {
    "questionId": 1,
    "correctChoiceIds": [1234, 4567],
    "choiceId": 0,
    "number": 2,
}, {
    "questionId": 2,
    "correctChoiceIds": [],
    "choiceId": 0,
    "number": 3
}];

//This filter gives me an array with list[0] and list[1]
var filterQuestion = $filter('filter')(list, { questionId: 1 }, true);

I want to filter all those with an empty array for their correctChoiceIds.

var filterNoCorrectChoice= $filter('filter')(list, { correctChoiceIds: [] }, true);

This is what I came up with but it simply gives me nothing. I'm not sure if this is the right way or why it results to nothing.

Answer 1

see demo

Use the filter like this,

  var filterNoCorrectChoice= $filter('filter')(list,function(item) {
        // must have array, and array must be empty
        return item.correctChoiceIds && item.correctChoiceIds.length === 0;
    });