Question

下面的逻辑component.js文件。

ngOnInit() {  
   const join= forkJoin( this.getReconciliationData()); //import { forkJoin } from 'rxjs/internal/observable/forkJoin';
   const subscribe= join.subscribe(result=>this.setReferenceTableData()); //Getting issue here
  }
  getReconciliationData() {
    this.commonService.getMasterData(MaterDataType.LOCALREFERENCES).subscribe(result=>{
      this.categories=result;
      this.categories.forEach(c => {
        c.children.forEach(subC => {
          this.references.push(...subC.references);
        });
        this.subCategories.push(...c.children);
      });
    });

  }
  setReferenceTableData=function(){
    this.dataSource=new MatTableDataSource(this.references);
  }

执行时间出错。

***core.js:7187 ERROR TypeError: You provided 'undefined' where a stream was expected. You can provide an Observable, Promise, Array, or Iterable.
    at Object.push../node_modules/rxjs/internal/util/subscribeTo.js.exports.subscribeTo (subscribeTo.js:29)
    at Object.from (from.js:11)
    at _loop_1 (forkJoin.js:42)
    at Observable._subscribe (forkJoin.js:67)
    at Observable.push../node_modules/rxjs/internal/Observable.js.Observable._trySubscribe (Observable.js:44)
    at Observable.push../node_modules/rxjs/internal/Observable.js.Observable.subscribe (Observable.js:30)
    at MedicalfileInternalServiceModelComponent.ngOnInit (medicalfile-internal-service-model.component.ts:69)
    at checkAndUpdateDirectiveInline (core.js:24503)
    at checkAndUpdateNodeInline (core.js:35163)
    at checkAndUpdateNode (core.js:35102).***

。我认为这里从getReconciliationData（）函数中查找返回对象。但就我而言，不需要返回声明。任何人都可以帮助我们解决这个问题。我需要一对一的函数执行。

Answer 1

forkJoin需要数组。

尝试这样：

const join= forkJoin( [this.getReconciliationData()])

Answer 2

尝试下面的修改代码。而且我认为您不需要forkJoin，因为您只有一个可观察的

  ngOnInit() {
    const subscribe = this.getReconciliationData().subscribe(result => {
      this.categories = result;
      this.categories.forEach(c => {
        c.children.forEach(subC => {
          this.references.push(...subC.references);
        });
        this.subCategories.push(...c.children);
      });
      this.setReferenceTableData();
    }
  };

  getReconciliationData(): Observable<any> {
    return this.commonService.getMasterData(MaterDataType.LOCALREFERENCES);

  }
  setReferenceTableData=function(){
    this.dataSource=new MatTableDataSource(this.references);
  }

Answer 3

您的getReconciliationData()方法不返回任何内容，它应该返回一个Observable，您希望将其传递给forkJoin()方法。但是，您确定只有一件事要订阅时需要使用它吗？

Angular 7 rxjs / forkJoin：您在期望流的位置提供了“ undefined”。您可以提供一个Observable，Promise，Array或Iterable

3 个答案: