Question

有人能告诉我为什么变量this.userDataObserver未定义会导致.next（）函数失败吗？在这里敲我的头。

我需要将一些数据推送到可以从其他组件访问的服务变量（试图避免使用本地存储）。

有人可以帮助我理解为什么这个变量在类中明确设置时是未定义的？

import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import { Observer } from 'rxjs/Observer';
import 'rxjs/add/operator/map';


@Injectable()
export class globalService {
//Sets logon token
userData:any;
userDataRetrieval: Observable<any>;
userDataObserver: any;
//Sets + updates user info
userInfo: any;
userInfoRetrieval: Observable<any>;
userInfoObserver: any;

constructor() {
    this.userDataRetrieval = new Observable(observer => {
        this.userDataObserver = observer;
    })
    this.userInfoRetrieval = new Observable(observer => {
        this.userInfoObserver = observer;
    })

}
setUser(userData: any) {
    this.userData = userData;
    this.userDataObserver.next(this.userData); this.userDataObserver comes back undefined when calling this function from my component.
}

saveUserInfo(userInfo: any) {
    this.userInfo = userInfo;
    this.userInfoObserver.next(this.userInfo);
}

}

Answer 1

而是直接致电this.userDataObserver.next(this.userData)，您应该使用以下内容并尝试这是否适合您：

setUser(userData: any) {
    this.userData = userData;
    this.userDataObserver = new Observable(observable => {
        observable.next()
    });
}

如果这对您不起作用，请告诉我......

Answer 2

回答您的具体问题：如果您查看the source of Observable，您会看到以下内容：

  /**
   * @constructor
   * @param {Function} subscribe the function that is  called when the Observable is
   * initially subscribed to. This function is given a Subscriber, to which new values
   * can be `next`ed, or an `error` method can be called to raise an error, or
   * `complete` can be called to notify of a successful completion.
   */
  constructor(subscribe?: (this: Observable<T>, subscriber: Subscriber<T>) => TeardownLogic) {
    if (subscribe) {
      this._subscribe = subscribe;
    }
  }

该代码显示Observable构造函数的参数是您订阅Observable时调用的回调。由于您从未在代码中调用subscribe，因此您传递给创建Observable的回调永远不会被调用。

现在，从您提供的代码示例中，很难理解您尝试实现的目标。也许您可以提供一些额外的背景/解释，以便您可以获得指导，以实现您的最终目标，无论它是什么。

当使用Observables时，变量回归未定义

2 个答案: