Create reducer about user state - ngrx

Question

I'm trying to apply reflux/ngrx on my current front-end project.
I want to take advantage of this in order to change a slight functionality: Change current user related tasks in order to use a single user state.
Current user related tasks: Currently, I'm using an traditional model in order to achieve user login process... UserService is able to check user credentials. Once it's been checked I store user information on an AppService:
export class LoginComponent implements OnInit {
private fb: FormBuilder;
private form:FormGroup;
private commty: UsersService;
private router: Router;
private appState: AppState;
private alerts: Array<Object>;
constructor()
{
this.alerts = [];
}
ngOnInit():void {
this.form = this.fb.group({
user: ['', Validators.required],
passwd: ['', Validators.minLength(6)]
});
}
public checkPasswd():void {
this.clearAlerts();
this.commty.checkPasswd(this.form.value.mail, this.form.value.passwd)
.subscribe(
(result: any) => {
this.appState.user = result;
this.router.navigate(['/app']);
},
(error: any) => {
this.addAlert(error.message);
}
);
}
private addAlert(message: string): void {
this.alerts.push({type: 'danger', msg: message});
}
public closeAlert(index): void {
this.alerts.splice(index, 1);
};
private clearAlerts(): void {
this.alerts.splice(0, this.alerts.length);
}
}
I'm a bit confused about how to move this code in order to use reflux/ngrx. I'ce read a bit about this topic, nevertheless I'm not quite able to figure out how to move my code. Up to now, I've created an single Store and User interfaces:
store.interface.ts:
export interface IStore {
user: IUser
sources: ISourceRedux;
}
user.interfcae.ts:
export interface IUser {
id: string;
name: string;
username: string;
customer: string;
}
The next step I think I need to do is to create reducers. This step is which I don't quite understand how build this code. Up to now
user.initialstate.ts:
export function initialUserState(): IUser {
return {
id: '',
name: '',
username: '',
customer: '',
sources: []
};
};
user.reducer.ts
export class User {
private static reducerName = 'USER_REDUCER';
public static reducer(user = initialUserState(), {type, payload}: Action) {
if (typeof User.mapActionsToMethod[type] === 'undefined') {
return user;
}
return User.mapActionsToMethod[type](user, type, payload);
}
// ---------------------------------------------------------------
// tslint:disable-next-line:member-ordering
private static mapActionsToMethod = {};
}
Which reducers I should create in order to:
Check credentials.
If credentials are right get this user and update User state store.
If credentials are wrong inform the process has failed.
Perhaps I'm merging concepts... I need some lights...
EDIT
public connect(user: string, currentPasswd: string, extraHttpRequestParams?: any): Observable<UserDTO> {
return this.checkPasswdWithHttpInfo(id, currentPasswd, extraHttpRequestParams)
.map((response: Response) => {
if (response.status === 204) {
return undefined;
} else {
return response.json();
}
}).catch((error: any) => {
if (error.status >= 500) {
return Observable.throw(new Error(error.status));
}
else { //if (error.status >= 400) {
const body = error.json() || '';
const code = body.error || JSON.stringify(body);
const message = body.message || JSON.stringify(body);
return Observable.throw(ApiError.create(code, message));
}
});
}

Answer 1

Ok so this is the next question of your "Integrate ngrx into my code" =).
What you're looking for is : https://github.com/ngrx/effects
The idea behind effects is that an effect let you catch an Action, do side effect (API call or whatever) and you can then dispatch another Action (often success or error).
Flow example to connect a user :
--| [from component] Dispatch action USER_CONNECT
--| [from user.effect.ts]
----| Catch action ofType('USER_CONNECT')
----| Do what you need to do (API call for ex)
----| When the response comes back :
------| If success : Dispatch USER_CONNECT_SUCCESS
------| If error : Dispatch USER_CONNECT_ERROR
Of course when you dispatch either USER_CONNECT_SUCCESS or USER_CONNECT_ERROR you can pass additional data in the payload (for example user information or the error).
Here's a full example :
#Injectable()
export class UsersEffects {
constructor(
private _actions$: Actions,
private _store$: Store<IStore>,
private _userService: UserService,
) { }
#Effect({ dispatch: true }) userConnect$: Observable<Action> = this._actions$
.ofType('USER_CONNECT')
.switchMap((action: Action) =>
this._userService.connect(action.payload.username, action.payload.password)
.map((res: Response) => {
if (!res.ok) {
throw new Error('Error while connecting user !');
}
const rslt = res.json();
return { type: 'USER_CONNECT_SUCCESS', payload: rslt };
})
.catch((err) => {
if (environment.debug) {
console.group();
console.warn('Error catched in users.effects.ts : ofType(USER_CONNECT)');
console.error(err);
console.groupEnd();
}
return Observable.of({
type: 'USER_CONNECT_ERROR',
payload: { error: err }
});
})
);
}
You can take a look into my project Pizza-Sync were I did something similar (except that I don't catch in case of error and do not dispatch if there's an error).