角度6-Rxjs 6-类型Observable< Object>不可分配给类型Observable< Item> [英] Angular 6 - Rxjs 6 - Type Observable<Object> is not assignable to type Observable<Item>

问题描述

将我的Angular项目从版本5更新到6后，出现此错误:

After updated my Angular project from version 5 to 6 I got this error:

类型Observable'<'Object>不能分配给类型Observable'<'Todo>.

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

在我的todo.service.ts

in my todo.service.ts

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，由于loadTodo将Observable'<'Object>类型分配给Observable'<'Array>类型，因此没有问题. 我使用了此链接来更改rxjs元素的导入方式，但是没有成功.有帮助吗?

The error points to addTodo, editTodo, and deleteTodo methods, loadTodo has no issues since it assigns Observable'<'Object> type to Observable'<'Array> type. I used this link to change the way rxjs elements are imported, but without success. Any help ?

推荐答案

httpClient方法是通用的，您必须键入响应，例如:

httpClient methods are generic, you have to type the response, for example:

    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))
    );
  }

这篇关于角度6-Rxjs 6-类型Observable&lt; Object&gt;不可分配给类型Observable&lt; Item&gt;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！