角6返回可观测

Question

我对角(使用AngularJs已经有很多年了)还很陌生，而且我还在和可观察到的东西做斗争:(我有这样的方法：

filterProducts(categoryId: string, questions: Question[], organisationId: string): Observable<any> {
  var formulas = this.formulaService.getFromSelectedAnswers(questions);
  let shouldFilter = this.shouldFilterProducts(categoryId, questions, formulas);
  if (!shouldFilter) return;

  return this.filterOrScore(categoryId, organisationId, formulas).pipe(map(products => {
    if (!products || !products.length) return;

    this.products.length = 0;
    this.products.push.apply(this.products, products);
    this.questionService.filterQuestionsByProducts(products, questions);      
    this.questionService.updateSession(questions);
  }));
}

if (!shouldFilter) return;行不对。我需要它返回一个可观察的，以便我的订阅工作。有人知道怎么做吗？

Answer 1

如果您不关心订阅中的返回值，则可以返回空值。这将完成可观察到的。

import {empty} from 'rxjs';

filterProducts(categoryId: string, questions: Question[], organisationId: string): Observable<any> {
  var formulas = this.formulaService.getFromSelectedAnswers(questions);
  let shouldFilter = this.shouldFilterProducts(categoryId, questions, formulas);
  if (!shouldFilter) return empty();

  return this.filterOrScore(categoryId, organisationId, formulas).pipe(map(products => {
    if (!products || !products.length) return empty();

    this.products.length = 0;
    this.products.push.apply(this.products, products);
    this.questionService.filterQuestionsByProducts(products, questions);      
    this.questionService.updateSession(questions);
  }));