角度2服务注入问题

Question

我的项目结构：

app.component.ts：

import { Component } from "@angular/core"
import { Todo } from './components/shared/todo.model'
import { todos } from "./components/shared/todo.data"
import {TodoService} from "./components/shared/todoService"
import {TodoService} from "./components/shared/todoService";

@Component({
    moduleId: module.id,
    selector: "app",
    templateUrl: "app.component.html",
    styleUrls: ['app.component.css'],
    providers: [TodoService]
})
export class AppComponent {
    title:string = "Angular 2Do";
}

待办事项-form.component.ts：

import {Component, Output, EventEmitter} from "@angular/core";
import {Todo} from "../shared/todo.model";
import {TodoService} from "../shared/todoService"

@Component({
    moduleId: module.id,
    selector: "todo-form",
    templateUrl: "todo-form.component.html",
    styleUrls: ["todo-form.component.css"],
})
export class TodoForm {
    ...
    constructor(private todoService:TodoService) {
        console.log(this.todoService);
        this.todoService.order = 2;
        console.log( this.todoService);
    }

}

待办事项-list.component.ts：

import {Component, Input, OnInit} from "@angular/core"

import { ITodo } from "../shared/todo.model"
import { TodoService } from "../shared/todoService"

@Component({
    moduleId: module.id,
    selector: "todo-list",
    templateUrl: "todo-list.component.html",
    styleUrls: ["todo-list.component.css"],
})
export class TodoListComponent implements OnInit {
    todos:ITodo[];

    ...

    constructor(private todoService:TodoService) {
        ...
        console.log(this.todoService);
        this.todoService.order=1;
        console.log(this.todoService);

    }
   ...

}

app是list和form组件的父级

我启动应用程序，我在控制台中看到了：

但如果展开全部，我看到：

哪个结果是实际的，为什么在第二个视图中我看到1和另一个2。

Answer 1

console.log＆＃39; +＆＃39;按钮只能显示对象的当前状态，而不能显示快照时的对象。

有关更深入的解释，请参阅console.log() async or sync?。

所以顺序：1，是对象的最终状态。

Answer 2

永远不要在组件中使用提供程序（providers: [TodoService]） 如

import { Component } from "@angular/core"
import { Todo } from './components/shared/todo.model'
import { todos } from "./components/shared/todo.data"
import {TodoService} from "./components/shared/todoService"
import {TodoService} from "./components/shared/todoService";

@Component({
    moduleId: module.id,
    selector: "app",
    templateUrl: "app.component.html",
    styleUrls: ['app.component.css']

})
export class AppComponent {
    title:string = "Angular 2Do";
}

它在组件初始化时创建新实例，因此只将providers放在模块中，即。 NgModule