Angular 6 - Rxjs 6 - 类型 Observable<Object> 不可分配给类型 Observable<Item>

Question

将我的 Angular 项目从版本 5 更新到版本 6 后出现此错误:

Type Observable'<'Object> is not assignable to type Observable'<'Todo>.

在我的 todo.service.ts 中

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { environment } from '../../../environments/environment';
import { Todo } from '../../../models/Todo';
import { Observable, of } from 'rxjs';
import { catchError } from 'rxjs/operators';
import 'rxjs/add/observable/throw';

@Injectable()
export class TodoService {

  todos: Todo[];

  constructor( private httpClient: HttpClient ) { }

  loadTodos(): Observable<Todo[]> {
    return this.httpClient.get<Todo[]>(`${environment.api}${environment.path}`).pipe(
      catchError((error: any) => Observable.throw(error))
    );
  }

  addTodo(todo: Todo): Observable<Todo> {
    return this.httpClient.post(`${environment.api}${environment.path}`, JSON.stringify(todo)).pipe(
      catchError((error: any) => Observable.throw(error))
    );
  }

  editTodo(todo: Todo): Observable<Todo> {
    return this.httpClient.put(`${environment.api}${environment.path}/${todo.id}`, JSON.stringify(todo)).pipe(
      catchError((error: any) => Observable.throw(error))
    );
  }

  deleteTodo(todo: Todo): Observable<Todo> {
    return this.httpClient.delete(`${environment.api}${environment.path}/${todo.id}`).pipe(
      catchError((error: any) => Observable.throw(error))
    );
  }
}

错误指向 addTodo、editTodo 和 deleteTodo 方法，loadTodo 没有问题，因为它将 Observable'<'Object> 类型分配给 Observable'<'Array> 类型。 我用了this link更改 rxjs 元素的导入方式，但没有成功。有什么帮助吗？

Answer 1

httpClient 方法是通用的，您必须键入响应，例如:

    addTodo(todo: Todo): Observable<Todo> {
        return this.httpClient.post(`${environment.api}${environment.path}`, JSON.stringify(todo)).pipe(
      catchError((error: any) => Observable.throw(error))
    );
  }

必须这样使用:

    addTodo(todo: Todo): Observable<Todo> {
    return this.httpClient.post<Todo>(`${environment.api}${environment.path}`, JSON.stringify(todo)).pipe(
      catchError((error: any) => Observable.throw(error))
    );
  }