Pobieranie danych, fabryka

Witam, mam mały problem. Mianowicie po kliknięciu przycisku w widoku powinny mi się pobrać dane za pomocą fabryki z zewnetrznego serwera(dane pogodowe, w zależności które miasto będzie w select'cie). Dane się pobierają z tym, że muszę kliknąc 2x przycisk.

Kontroler:

(function(){
  angular
    .module('projectApp')
    .controller('SinglearticleCtrl', SinglearticleCtrl);

  SinglearticleCtrl.$inject=['$routeParams', 'articlesFactory', 'weatherfactory']

  function SinglearticleCtrl($routeParams, articlesFactory, weatherfactory){
    var sa=this;

    sa.show=false;
    sa.id=$routeParams.id;
    sa.article=articlesFactory.getOneArticle(sa.id);
    sa.cities=weatherfactory.getCities();
    sa.weatherData=weatherData;

    function weatherData(city){
      sa.weather=weatherfactory.GetWeather(city);
      sa.show=true;
    }
  }
})();

Fabryka:

(function(){
  angular
    .module('projectApp')
    .factory('weatherfactory', weatherfactory);

  weatherfactory.$inject=['$http'];

  function weatherfactory($http){
    var cities=[
      {name: "Łódź", link: "http://api.openweathermap.org/data/2.5/weather?q=Lodz,pl"},
      {name: "Warszawa", link: "http://api.openweathermap.org/data/2.5/weather?q=Warszawa,pl"}

    ];
    var weat={};

    var service={
      getCities: getCities,
      GetWeather: _GetWeather
    };
    return service;

    function _GetWeather(link){
      $http.get(link).success(function(data){
        weat=data;
      });
      return weat;
    }


    function getCities(){
      return cities;
    }
  }
})();

Widok:

<div class="row">
  <div class="col-md-8">
    <div class="panel panel-primary">
      <div class="panel-heading">{{sa.article.title}}</div>
      <div class="panel-body">{{sa.article.content}}</div>
    </div>
  </div>

  <div class="col-md-4">
    <div class="well">
      <div class="row">
        <div class="col-md-8">
          <select class="form-control" ng-model="sa.city">
            <option ng-repeat="city in sa.cities" value="{{city.link}}">{{city.name}}</option>
          </select>
        </div>
        <div class="col-md-4">
          <button class="btn btn-primary" ng-click="sa.weatherData(sa.city)">Wybierz</button>
        </div>
        <div ng-if="sa.show">
          {{sa.weather.name}}
        </div>
      </div>
    </div>
  </div>
</div>