What type of Typescript return value should I use for a $http call that returns nothing other than success?

Question

I created a service using Typescript:

class ConfigService implements IConfigService {

    public admin = {};
    public adminBackup = {};
    public user = {};
    public loaded = false;

    constructor(
        private $http: ng.IHttpService,
        private $q: ng.IQService
        ) {

    }

    static $inject = [
        '$http',
        '$q'
    ];

    put = ():ng.IHttpPromise<> => {
        var defer = this.$q.defer();
        if (angular.equals(this.admin, this.adminBackup)) {
            return defer.resolve();
        } else {
            this.$http({
                data: {
                    adminJSON: JSON.stringify(this.admin),
                    userJSON: JSON.stringify(this.user)
                },
                url: '/api/Config/Put',
                method: "PUT"
            })
                .success(function (data) {
                    this.adminBackup = angular.copy(this.admin);
                    this.userBackup = angular.copy(this.user)
                    return defer.resolve();
                });
        }
        return defer.promise;
    };

}

I also created this interface:

interface IConfigService {
     put(): ng.IHttpPromise<>;
}

However the code is giving me an error saying:

Error   3   Cannot convert 'void' to 'ng.IHttpPromise<any>'.    

Error   4   Cannot convert 'ng.IPromise<{}>' to 'ng.IHttpPromise<any>':
    Type 'ng.IPromise<{}>' is missing property 'success' from type 'ng.IHttpPromise<any>'.  

Answer 1

Use

ng.IPromise<void>

Also you could let it implicitly type it for you if you don't declare a return type and don't use that interface.

Also there should be no return statement here :

return defer.resolve();

Just :

defer.resolve();