GET有時(shí)我在處理請(qǐng)求時(shí)遇到一些問(wèn)題Angular。我正在使用ReplaySubject并返回，Observable但有時(shí)在應(yīng)用程序的重新加載中，get請(qǐng)求正在工作，但它正在獲取null數(shù)據(jù)或消息No content，盡管有數(shù)據(jù)。經(jīng)過(guò) 3-4 次嘗試后，它會(huì)顯示數(shù)據(jù)。該請(qǐng)求get有效，但有時(shí)為空，有時(shí)給我數(shù)據(jù)。有人可以幫我解決這個(gè)問(wèn)題嗎？如果有可能給出任何使用ReplaySubject或類(lèi)似的想法，因?yàn)槲倚枰看沃匦录虞d頁(yè)面以獲取新數(shù)據(jù)。這是我的Frontend部分。export class ModelDataService {  public baseUrl = environment.backend;  private data = new ReplaySubject<any>(1);  public userID = this.authService.userID;  constructor(private http: HttpClient, private authService: AuthService) {  }   public getJSON() {    return this.http.get(`${this.baseUrl}/data/${this.userID}`).subscribe(res => this.data.next(res));  }  public dataModel(): Observable<any> {    return this.data.asObservable();  }  public setData(data: Model) {    const api = `${this.baseUrl}/data`;    const user_id = this.authService.userID;    this.http.post(api, data, {      headers: {user_id}    }).subscribe(res => this.data.next(res));  }  public updateDate(id: string, dataModel: Model) {    const api = `${this.baseUrl}/data/${id}`;    return this.http.put(api, dataModel).subscribe(res => res);  }}這是component我得到的數(shù)據(jù)  ngOnInit() {    this.authService.getUserProfile(this.userID).subscribe((res) => {      this.currentUser = res.msg;    });    this.modelDataService.getJSON();    this.model$ = this.modelDataService.dataModel();    this.model$.subscribe((test) => {      this.model = test;    });    this.model$.subscribe((test) => {      this.model = test;    });  }這就是這backend部分。const ModelData = require("../models/data");async show(req, res) {let modelData;await ModelData.findOne({user: req.params.id}, (error, user) => {   modelData = user;}); if (!modelData) {    res.status(204).json({error: "No Data"});    return;    }return res.status(200).send(modelData);},routes.get("/data/:id", ModelDataController.show);routes.post("/data", ModelDataController.store);routes.put("/data/:id", ModelDataController.update);