So I was working on a new component in Angular and in the ngOninit I have the following asynchronous functions below...
This.getUserProfile needs to be finished before I can call this.getPrivateGroup() and this.getPrivateGroup() needs to be finished before I can call this.loadGroupPosts(). I know I could write these functions inside the callback of the asynchronous requests, but I was wondering if there is a way to keep it in ngOnInit to keep it cleaner?
Anyone has an idea?
ngOnInit() {
this.getUserProfile();
// my-workplace depends on a private group and we need to fetch that group and edit
// the group data before we proceed and get the group post
if (this.isItMyWorkplace) {
this.getPrivateGroup();
}
this.loadGroupPosts();
}
getUserProfile() {
this._userService.getUser()
.subscribe((res) => {
this.user = res.user;
console.log('log user', this.user);
this.profileImage = res.user['profile_pic'];
this.profileImage = this.BASE_URL + `/uploads/${this.profileImage}`;
}, (err) => {
this.alert.class = 'alert alert-danger';
if (err.status === 401) {
this.alert.message = err.error.message;
setTimeout(() => {
localStorage.clear();
this._router.navigate(['']);
}, 3000);
} else if (err.status) {
this.alert.class = err.error.message;
} else {
this.alert.message = 'Error! either server is down or no internet connection';
}
});
}
getPrivateGroup() {
console.log('user check', this.user);
this.groupService.getPrivateGroup(`${this.user.first_name}${this.user.last_name}`)
.subscribe((group) => {
console.log('received response', group)
})
}
// !--LOAD ALL THE GROUP POSTS ON INIT--! //
loadGroupPosts() {
this.isLoading$.next(true);
this.postService.getGroupPosts(this.group_id)
.subscribe((res) => {
// console.log('Group posts:', res);
this.posts = res['posts'];
console.log('Group posts:', this.posts);
this.isLoading$.next(false);
this.show_new_posts_badge = 0;
}, (err) => {
swal("Error!", "Error while retrieving the posts " + err, "danger");
});
}
// !--LOAD ALL THE GROUP POSTS ON INIT--! //
4 Answers
You can use basic promises with async/await.
async ngOnInit() {
await this.getUserProfile(); // <-- 1. change
// my-workplace depends on a private group and we need to fetch that group and edit
// the group data before we proceed and get the group post
if (this.isItMyWorkplace) {
this.getPrivateGroup();
}
this.loadGroupPosts();
}
async getUserProfile() {
this._userService.getUser()
.subscribe((res) => {
this.user = res.user;
console.log('log user', this.user);
this.profileImage = res.user['profile_pic'];
this.profileImage = this.BASE_URL + `/uploads/${this.profileImage}`;
return true; // <-- this
}, (err) => {
this.alert.class = 'alert alert-danger';
if (err.status === 401) {
this.alert.message = err.error.message;
setTimeout(() => {
localStorage.clear();
this._router.navigate(['']);
}, 3000);
} else if (err.status) {
this.alert.class = err.error.message;
} else {
this.alert.message = 'Error! either server is down or no internet connection';
}
throw err;
});
}
You could instead leverage RxJS and use a switchMap something like this (syntax NOT checked):
getData(): Observable<string[]> {
return this._userService.getUser()
.pipe(
switchMap(userInfo=> {
return this.getPrivateGroup();
}),
catchError(this.someErrorHandler)
);
}
One way to do is, return the Observable instead of subscribing in the getPrivateGroup()
getPrivateGroup() {
console.log('user check', this.user);
return this.groupService.getPrivateGroup(`${this.user.first_name}${this.user.last_name}`)
}
And then, subscribe to the data where you want the chain the this.loadGroupPosts()
if (this.isItMyWorkplace) {
this.getPrivateGroup().subscribe(group => {
this.group = group; //you probably want to assign the group data
this.loadGroupPosts()});
}
you could also use the 3rd part of your subscribe function when its completed i am not quite sure if this is a clean solution, in my opinion it is.
ngOnInit() {
this.getUserProfile();
}
getUserProfile() {
this._userService.getUser()
.subscribe((res) => {
this.user = res.user;
console.log('log user', this.user);
this.profileImage = res.user['profile_pic'];
this.profileImage = this.BASE_URL + `/uploads/${this.profileImage}`;
}, (err) => {
this.alert.class = 'alert alert-danger';
if (err.status === 401) {
this.alert.message = err.error.message;
setTimeout(() => {
localStorage.clear();
this._router.navigate(['']);
}, 3000);
} else if (err.status) {
this.alert.class = err.error.message;
} else {
this.alert.message = 'Error! either server is down or no internet connection';
}
}, () => {
// my-workplace depends on a private group and we need to fetch that group and edit
// the group data before we proceed and get the group post
if (this.isItMyWorkplace) {
this.getPrivateGroup();
}
});
}
getPrivateGroup() {
console.log('user check', this.user);
this.groupService.getPrivateGroup(`${this.user.first_name}${this.user.last_name}`)
.subscribe((group) => {
console.log('received response', group)
}, error => {
console.log(error)
}, () => {
this.loadGroupPosts();
})
}
loadGroupPosts() {
this.isLoading$.next(true);
this.postService.getGroupPosts(this.group_id)
.subscribe((res) => {
// console.log('Group posts:', res);
this.posts = res['posts'];
console.log('Group posts:', this.posts);
this.isLoading$.next(false);
this.show_new_posts_badge = 0;
}, (err) => {
swal("Error!", "Error while retrieving the posts " + err, "danger");
});
}
