How to set a variable from an $http call then use it in the rest of the application WITHOUT making the whole application asynchronous

Question

I have this data

{
  \"config\": {
    \"RESTAPIURL\": \"http://myserver/myrestsite\"
  }
}

and I have this factory that reads that data

Answer 1

I would pass a callback to the getURL method, and save the URL when it returns. Then I would attach any subsequent requests to that callback. Here I am assuming that you are doing something similar with api.AUTH that you don't have a reference to in your code.

Pass a callback to the getURL method in the api service.

angular.module('myApp').factory('api', ["$http", "$q",

function ($http, $q) {

    function _getConfiguration() {
        var deferred = $q.defer();
        $http.get('/scripts/constants/config.json')
            .success(function (data) {
            deferred.resolve(data);
        })
            .error(function (data, status) {
            deferred.reject(data, status);
        });
        return deferred.promise;
    }

    return {
        getURL: function (cb) {
            var that = this;
            if (that.URL) {
                return cb(that.URL);
            }

            _.getConfiguration().then(function (data) {
                that.URL = data.config.RESTAPIURL + "/api";
                cb(that.URL);
            });
        }
    }
}]);

And in your AuthService, wrap your _get inside a callback like this:

angular.module('myApp').factory('AuthService', function ($http, $q, api, NotificationService) {

    function _get(creds) {
        var deferred = $q.defer();
        var getCallback = function (url) {

            $http({
                method: 'GET',
                url: url + api.AUTH,
                headers: {
                    'Authorization': 'Basic ' + creds
                }
            })
                .success(function (data, status, results, headers) {
                deferred.resolve(results);
            })
                .error(function (data, status) {
                NotificationService.redirect(status);
                deferred.reject(data, status);
            });
        };
        api.getURL(getCallback);
        return deferred.promise;
    }

    return {
        get: _get
    };
});