Is it possible for an Angular Service to trigger a function in the Controller that then calls the same service?

Question

Is it possible for an Angular Service to trigger a function in the Controller that then calls the same service?

Presenting my controller

RegisterController.$inject = ['$location', '$scope', 'Authentication'];

function RegisterController($location, $scope, Authentication){
  var vm = this;

  vm.register = register;

  function register(){
    Authentication.register(vm.email, vm.password, vm.confirm_password, vm.username);
  }

  function display_registration_error(error_list){
    console.log("This seems odd")
  }

}

Introducing my service

function Authentication($cookies, $http, RegisterController){

var Authentication = {
  register: register
};

return Authentication;


// Registration process
function register(email, password, confirm_password, username){
  return $http.post('/api/v1/accounts/',{
    username: username,
    password: password,
    confirm_password: confirm_password,
    email: email
  }).then(registerSuccess, registerError);
}


function registration_failure(response){
  error_list = response["data"];
  RegisterController.display_registration_error(error_list);
}

}

The sequence is as follows register (controller) -> post (service) -> registration_failure (service) ->

display_registration_error (controller)

I suspect this might be causing the error

Error: [$injector:unpr] Unknown provider: RegisterControllerProvider <- RegisterController <- Authentication

Why is this error occurring and can it be resolved?

javascript angularjs service controller

Answer 1

Answer №1

Injecting controllers in services is not possible due to the difference in instantiation behavior. Controllers are created each time a directive is instantiated, while services are only instantiated once during startup.

To work around this, you can modify the Authentication.register function to return a promise. This can be achieved by utilizing the $q service.

If you prefer not to handle authentication outcomes within the Authentication service, you can simply return the promise generated by the $http.post call.

Alternatively, you can directly return the $http.post response:

service function Authentication($cookies, $http){

   var Authentication = {
     register: register
   };

    return Authentication;


   // Registration logic
  function register(email, password, confirm_password, username){
    return $http.post('/api/v1/accounts/',{
    username: username,
    password: password,
    confirm_password: confirm_password,
    email: email
   });
  }

controller

RegisterController.$inject = ['$location', '$scope', 'Authentication'];

function RegisterController($location, $scope, Authentication){
  var vm = this;

  vm.register = register;

  function register(){
    Authentication.register(vm.email, vm.password, vm.confirm_password,    vm.username).then(onSuccess, onError);
  }

  function onSuccess(result) {
    console.log("HTTP request succeeded");
  }

  function onError(result) {
    console.log("HTTP request failed");
  }
}

Custom promise handling: service

function Authentication($cookies, $http, $q){

var Authentication = {
  register: register
};

return Authentication;


// Registration logic
function register(email, password, confirm_password, username){
    var deferred = $q.defer();
   $http.post('/api/v1/accounts/',{
     username: username,
     password: password,
     confirm_password: confirm_password,
     email: email
   }).then(function(result) {
       deferred.resolve(result);
   }, function(error) {
       deferred.reject(result);
   });

   return deferred.promise();
 }

}

controller

RegisterController.$inject = ['$location', '$scope', 'Authentication'];

function RegisterController($location, $scope, Authentication){
  var vm = this;

  vm.register = register;

  function register(){
    Authentication.register(vm.email, vm.password, vm.confirm_password, vm.username).then(onSuccess, onError);
  }

  function onSuccess(result) {
    console.log("Authentication success");
  }

  function onError(result) {
    console.log("Authentication success");
  }

}

It's advisable to implement and return your own promise to abstract the authentication process from the controller, allowing for flexibility in handling authentication results.

Answer 2

Injecting controllers in services is not possible due to the difference in instantiation behavior. Controllers are created each time a directive is instantiated, while services are only instantiated once during startup.

To work around this, you can modify the Authentication.register function to return a promise. This can be achieved by utilizing the $q service.

If you prefer not to handle authentication outcomes within the Authentication service, you can simply return the promise generated by the $http.post call.

Alternatively, you can directly return the $http.post response:

service function Authentication($cookies, $http){

   var Authentication = {
     register: register
   };

    return Authentication;


   // Registration logic
  function register(email, password, confirm_password, username){
    return $http.post('/api/v1/accounts/',{
    username: username,
    password: password,
    confirm_password: confirm_password,
    email: email
   });
  }

controller

RegisterController.$inject = ['$location', '$scope', 'Authentication'];

function RegisterController($location, $scope, Authentication){
  var vm = this;

  vm.register = register;

  function register(){
    Authentication.register(vm.email, vm.password, vm.confirm_password,    vm.username).then(onSuccess, onError);
  }

  function onSuccess(result) {
    console.log("HTTP request succeeded");
  }

  function onError(result) {
    console.log("HTTP request failed");
  }
}

Custom promise handling: service

function Authentication($cookies, $http, $q){

var Authentication = {
  register: register
};

return Authentication;


// Registration logic
function register(email, password, confirm_password, username){
    var deferred = $q.defer();
   $http.post('/api/v1/accounts/',{
     username: username,
     password: password,
     confirm_password: confirm_password,
     email: email
   }).then(function(result) {
       deferred.resolve(result);
   }, function(error) {
       deferred.reject(result);
   });

   return deferred.promise();
 }

}

controller

RegisterController.$inject = ['$location', '$scope', 'Authentication'];

function RegisterController($location, $scope, Authentication){
  var vm = this;

  vm.register = register;

  function register(){
    Authentication.register(vm.email, vm.password, vm.confirm_password, vm.username).then(onSuccess, onError);
  }

  function onSuccess(result) {
    console.log("Authentication success");
  }

  function onError(result) {
    console.log("Authentication success");
  }

}

It's advisable to implement and return your own promise to abstract the authentication process from the controller, allowing for flexibility in handling authentication results.

Is it possible for an Angular Service to trigger a function in the Controller that then calls the same service?

Answer №1

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