angularjs - How to change pyramid request to promises with $q -

i want change pyramid request promises $q.

app.controller('ctrl', function ($scope, $http, $q) {  $http.post('http://localhost:1235',data_post1).success(function (data){     console.log("1");     $http.post('http://localhost:1236',data_post2).success(function (data){         console.log("2");         $http.post('http://localhost:1237',data_post3).success(function (data){             console.log("3");             $http.post('http://localhost:1238',data_post4).success(function (data){                 console.log("4");             });         });         }); });  } 

i'm never use $q before.

so best practice pull http requests out of controller

so if had factory

app.factory("foosrvc", ["$q", "$http", function($q, $http){     return {         data1: function(postdata){             var deferred = $q.defer();             $http.post("", postdata).success(function(results){                 deferred.resolve(results);             });              return deferred.promise;         },         data2: function(postdata){             var deferred = $q.defer();             $http.post("", postdata).success(function(results){                 deferred.resolve(results);             });              return deferred.promise;         }     }; }]); 

then controller like

app.controller("ctrl", ["$scope", "foosrvc", function($scope, foosrvc){     foosrvc.data1(datatopost).then(function(results){         // here possibly         foosrvc.data2(moredatatopost).then(function(moreresults){             // here possibly         });     }); }]);