Angular 7:从订阅内部调用时，ChangeDetectorRef detectChanges()导致无限循环 [英] Angular 7: ChangeDetectorRef detectChanges() causes infinite loop when called from inside a subscription

问题描述

在阅读了所有与变更检测和类似帖子相关的材料之后，我在这里发布了内容，但未能解决我的问题.

I am posting here after reading all the material related to change detection and similar post and failing to solve my problem.

ChangeDetectorRef detectChanges()会导致无限循环.如果我不打电话给detectChanges，我会收到ExpressionChangedAfterCheck错误.我真的不知道该怎么解决，为什么会出现ExpressionChangedAfterCheck错误

ChangeDetectorRef detectChanges() causes infinite loop when called from inside a subscription. If I don't call detectChanges, I get ExpressionChangedAfterCheck error. I seriously don't know how to solve, and why is the ExpressionChangedAfterCheck error comes

ngAfterViewInit() {
    this.route.params.subscribe((params) => {
      this.userId = params.userId;
      if (this.userId != undefined) {
        this.loadActivity();
      }
      else {
        alert("Userid not supplied");
      }
      this.cdRef.detectChanges();
    });
  }

  loadActivity() {
    while(this.layers.length > 0){
      this.layers.pop();
    }
    this.loading = true;
    this.userService.authenticatedGet(ApiUrls.GetLocation(this.userId, this.activity.from.getTime(), this.activity.to.getTime()), {}).subscribe(
      (res:any) => {
        this.user = res.user;
        this.loading = false;
        // other logic
        this.cdRef.detectChanges();
        console.log("Loading is " + this.loading);
      }
    );
  }

注意:仅当值与ngIf绑定时，才会出现此问题.

Note: This problem is there only when the value is bound with ngIf.

推荐答案

我解决了这个问题.问题不是生命周期，而是ngx-leaflet项目中的指令leaflet.

I resolved this. Issue was not with the lifecycle but with a directive leaflet from ngx-leaflet project.

当我删除与传单相关的指令并进行绑定时，所有错误都消失了.

When I removed leaflet related directive and bindings all errors vanished.

错误也随之出现:

<ng-container *ngIf="!loading">
    <div
      class="map"
      leaflet
      (leafletMapReady)="onMapReady($event)"
      [leafletOptions]="options"
      [leafletLayers]="layers"
      [leafletLayersControl]="layersControl">
    </div>
</ng-container>

我尝试过交替添加detectChanges和markForCheck，但还是没有运气.

I tried adding detectChanges and markForCheck alternatively, but again got no luck.

  onMapReady(map: Map) {
    this.map = map;
    setTimeout(() => map.invalidateSize(), 1000);
    this.route.params.subscribe(params => {
      this.userId = params["userId"];
      this.loadActivity();
    });
    this.cdRef.markForCheck();
  }

最后，我在编写此答案时放弃了传单，然后尝试Angular-Google-Maps.

Finally, I ditched leaflet while writing this answer, and I am going to try Angular-Google-Maps.

是的，A-G-M工作正常.

And yeah A-G-M is working fine.

这篇关于Angular 7:从订阅内部调用时，ChangeDetectorRef detectChanges()导致无限循环的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！