angular-js过滤器查找空字符串

Question

I'd like to use the filters to return all values that have an empty string for a particular field.

That is, in the code:

var groups = $filter('unique')(addresses, 'country');
var groupedByCountry = [];

angular.forEach(groups, function (value, key) {
   var selectedGroup = value['country'];
   var grouped = $filter('filter')(addresses, { country: selectedGroup });
   this.push(grouped);
}, groupedByCountry);

As can be seen in http://jsfiddle.net/b7cjM/ , it creates groups as expected where a country is specified, but I'd like the last group to contain only the addresses that have no country specified (instead of, as currently, a group of all addresses in existence).

Is this possible using angularjs?

**

As suggested by punund, I wrote a 'groupBy' filter [a naive conversion of the 'unique' filter: http://jsfiddle.net/b7cjM/1 ], which is a much simpler solution to my problem than the one I was attempting. I suspect a custom 'filterByEmpty' of this type is also the solution for the problem as presented.

Answer 1

underscore or lodash may work better for you:

groupedBy = _.groupBy($scope.addresses, 'country');

Empty strings are properly taken into account, and you don't need the second filter. Another option would be to implement a kind of "groupBy" angular filter yourself.