我正在学习Angular,并尝试监听包含http请求值的变量。这是服务
export class UsersService {
message = new Subject<string>();
constructor(private http: HttpClient) { }
addUser(userData: {username, email, password, school}) {
this.http.post<any>('http://127.0.0.1/apiapp/insert.php', userData).subscribe( (r) => {
this.message = r.message;
});
}
[当我记录该消息时,我得到success
现在,我想调用此函数并从组件中监听该变量
result = '';
private resultSubscription: Subscription;
ngOnInit() {
this.resultSubscription = this.userS.message.subscribe( (r) => {
this.result = r;
});
}
addPost(userData: {username: string, email: string, password: string, school: string}) {
this.userS.addUser(userData);
console.log(this.result);
}
我得到一个空白数据(什么都没有记录到控制台中的空白行)。为什么会这样以及如何解决呢?在此先感谢
您在这里有3个问题。
console.log(this.result)
的位置上存在一些异步问题您希望在主题上致电.asObservable
以使主题可观察到
export class UsersService {
message = new Subject<string>();
constructor(private http: HttpClient) { }
addUser(userData: {username, email, password, school}) {
this.http.post<any>('http://127.0.0.1/apiapp/insert.php', userData).subscribe( (r) => {
// .next is how you send data via a subject
this.message.next(r.message);
});
}
result = '';
private resultSubscription: Subscription;
ngOnInit() {
// Get subject as observable
this.resultSubscription = this.userS.message.asObservable().subscribe( (r) => {
this.result = r;
// by logging here we can ensure that the result will be populated
console.log(this.result);
});
}
addPost(userData: {username: string, email: string, password: string, school: string}) {
this.userS.addUser(userData);
}
// It is important to unsubscribe for your observable when the component is destroyed
ngOnDestroy(): void { this.resultSubscription.unsubscribe(); }