Angular/Ionic RXJS pipe/map 重新加载时未定义元素
Angular/Ionic RXJS pipe/map undefined element on reload
简单的管理员角色检查方法:
isAdmin() {
return this.userProfileObservable.pipe(map((profile: UserObject) => {
//Here I can place some delaying code and it works!!!
return profile != null ? profile.role === 'admin' : false;
}));
}
如果我从上一页导航到该页面并且路由器调用 AdminGuard,则工作正常:
canActivate(
next: ActivatedRouteSnapshot,
state: RouterStateSnapshot): Observable<boolean> {
return this.auth.isAdmin();
}
Observables 在服务构造函数中初始化:
private _userProfileSubject: BehaviorSubject<UserObject>;
private _firebaseUserSubject: BehaviorSubject<firebase.User>;
private userProfileCollection: AngularFirestoreDocument<UserObject>;
public userProfileObservable: Observable<UserObject>;
private authObserver: firebase.Unsubscribe;
constructor(
private afAuth: AngularFireAuth,
private afs: AngularFirestore, ) {
// Init observers with null initial value
this._userProfileSubject = new BehaviorSubject(new UserObject()) as BehaviorSubject<UserObject>;
this._firebaseUserSubject = new BehaviorSubject(null) as BehaviorSubject<firebase.User>;
this.userProfileObservable = this._userProfileSubject.asObservable();
this.authObserver = afAuth.auth.onAuthStateChanged((user) => {
this._firebaseUserSubject.next(user);
if (user == null) {
this._userProfileSubject.next(null);
return;
}
this.userProfileCollection = afs.collection<UserObject>('Users').doc(user.uid);
// Monitor auth changes and update behaviorSubject -> observable <UserObject>
this.userProfileCollection.snapshotChanges().subscribe((action => {
const data = action.payload.data() as UserObject;
data.uid = action.payload.id;
this._userProfileSubject.next(data);
return data;
}));
});
}
但是如果我重新加载页面/直接导航到受 AdminGuard 保护的路由,property/element in pipe -> map -> "profile" 由于某种原因变得未定义。
它好像还没有加载所有东西,好像我之前在 isAdmin 方法中执行了 "BIG HACK" 和 await/delay,然后它再次工作...
能否请您进行以下更改并尝试:
在您的服务中,让我们用 null 初始化 BehavorSubject;
this._userProfileSubject: BehaviorSubject<UserObject> = new BehaviorSubject(null);
然后更新您的 isAdmin() 方法,使其忽略 userProfileObservable
的第一个 'null' 值并等待直到它发出 NOT NULL 值 [为此使用 skipWhile()
运算符] 像这样:
isAdmin() {
return this.userProfileObservable
.pipe(
//it will skip all null value until source sobservable emits a NOT NULL value; i.e. it will wait until your service's subscribe get the response and emits a NOT NULL value of UserObject
skipWhile(u => !u),
map((profile: UserObject) => {
//Here I can place some delaying code and it works!!!
return profile != null ? profile.role === 'admin' : false;
})
);
}
简单的管理员角色检查方法:
isAdmin() {
return this.userProfileObservable.pipe(map((profile: UserObject) => {
//Here I can place some delaying code and it works!!!
return profile != null ? profile.role === 'admin' : false;
}));
}
如果我从上一页导航到该页面并且路由器调用 AdminGuard,则工作正常:
canActivate(
next: ActivatedRouteSnapshot,
state: RouterStateSnapshot): Observable<boolean> {
return this.auth.isAdmin();
}
Observables 在服务构造函数中初始化:
private _userProfileSubject: BehaviorSubject<UserObject>;
private _firebaseUserSubject: BehaviorSubject<firebase.User>;
private userProfileCollection: AngularFirestoreDocument<UserObject>;
public userProfileObservable: Observable<UserObject>;
private authObserver: firebase.Unsubscribe;
constructor(
private afAuth: AngularFireAuth,
private afs: AngularFirestore, ) {
// Init observers with null initial value
this._userProfileSubject = new BehaviorSubject(new UserObject()) as BehaviorSubject<UserObject>;
this._firebaseUserSubject = new BehaviorSubject(null) as BehaviorSubject<firebase.User>;
this.userProfileObservable = this._userProfileSubject.asObservable();
this.authObserver = afAuth.auth.onAuthStateChanged((user) => {
this._firebaseUserSubject.next(user);
if (user == null) {
this._userProfileSubject.next(null);
return;
}
this.userProfileCollection = afs.collection<UserObject>('Users').doc(user.uid);
// Monitor auth changes and update behaviorSubject -> observable <UserObject>
this.userProfileCollection.snapshotChanges().subscribe((action => {
const data = action.payload.data() as UserObject;
data.uid = action.payload.id;
this._userProfileSubject.next(data);
return data;
}));
});
}
但是如果我重新加载页面/直接导航到受 AdminGuard 保护的路由,property/element in pipe -> map -> "profile" 由于某种原因变得未定义。
它好像还没有加载所有东西,好像我之前在 isAdmin 方法中执行了 "BIG HACK" 和 await/delay,然后它再次工作...
能否请您进行以下更改并尝试:
在您的服务中,让我们用 null 初始化 BehavorSubject;
this._userProfileSubject: BehaviorSubject<UserObject> = new BehaviorSubject(null);
然后更新您的 isAdmin() 方法,使其忽略 userProfileObservable
的第一个 'null' 值并等待直到它发出 NOT NULL 值 [为此使用 skipWhile()
运算符] 像这样:
isAdmin() {
return this.userProfileObservable
.pipe(
//it will skip all null value until source sobservable emits a NOT NULL value; i.e. it will wait until your service's subscribe get the response and emits a NOT NULL value of UserObject
skipWhile(u => !u),
map((profile: UserObject) => {
//Here I can place some delaying code and it works!!!
return profile != null ? profile.role === 'admin' : false;
})
);
}