Question

我正在学习Angular 2.我正在使用Angular 2构建一个简单的CRUD应用程序。我面临一个问题，在插入记录后，表在客户端没有刷新，但是，它正在插入数据库。但是，如果我重新加载网页，它正在更新记录，但如果我添加新记录，更新记录，或删除不更新或刷新表的记录。我的代码出了什么问题？

app.component.ts

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
}

app.component.html

<app-book></app-book>

book.component.ts

import {Component, OnInit, Output, EventEmitter} from '@angular/core';
import {BookService} from './book.service';
import {Book} from './book';

@Component({
    selector: 'app-book',
    templateUrl: './book.component.html'
})
export class BookComponent implements OnInit{
    books: Book[];
    statusMessage: string;
    book = new Book();
    constructor(private _bookService: BookService){}

    ngOnInit(): void {
        console.log("calling ngOnInit()::::");
        this.getBooks();
    }

    getBooks(): void{
        console.log("Inside getBooks():::::")
        this._bookService.getAllBooks()
            .subscribe((bookData) => this.books = bookData,
            (error) =>{
                console.log(error);
                this.statusMessage = "Problem with service. Please try again later!";
            });
        console.log("end of getBooks():::::")
    }

    addBook(): void{
        console.log("inside the addBook()::::::")
        this._bookService.addBook(this.book)
            .subscribe((bookData) => {console.log(bookData); this.books.push(bookData)},
            (error) =>{
                console.log(error);
                this.statusMessage = "Problem with service. Please try again later!";
            });
        this.getBooks();
        this.reset();
        console.log("end of addBook()::::");
    }

    updateBook(bookId: string){
        console.log("Inside the updateBook()::::::Book id::::"+bookId);
        this._bookService.getBookById(bookId)
            .subscribe((bookData) => this.book = bookData),
            (error) => {
                console.log(error);
                this.statusMessage = "Problem with service. Please try again later!";
            }
        this.getBooks();
        console.log("end of updateBook()::::::");
    }

    deleteBook(bookId: string){
        console.log("Inside the deleteBook()::::Book id::::"+bookId);
        this._bookService.deleteBook(bookId)
            .subscribe((response) => console.log(response),
            (error) =>{
                console.log(error);
                this.statusMessage = "Problem with service. Please try again later!";
            });
        this.getBooks();
        this.reset();
        console.log("end of deleteBook():::::::");
    }

    private reset(){
        console.log("inside the reset():::::::");
        this.book.title = null;
        this.book.author = null;
        console.log("end of reset():::::::");
    }
}

即使我尝试在addBook（），deleteBook（），updateBook（）的末尾调用this.getBooks（）方法，但仍然没有刷新或更新。只有在我们重新加载网页时才会更新或刷新。

book.component.html

<div>
    <form>
        <input type = "hidden" [(ngModel)] = "book.id" name = "id" /> 
        <label>Book Title</label>
        <input type = "text" [(ngModel)] = "book.title" name = "title"/><br/>
        <label>Book Author</label>
        <input type = "text" [(ngModel)] = "book.author" name = "author"/><br/>
        <button (click) = "addBook()">Add Book</button>
    </form>
</div>
<div>
    <table border = "1">
        <tr>
            <td>Id</td>
            <td>Title</td>
            <td>Author</td>
            <td>Actions</td>
        </tr>
        <tr *ngFor = "let book of books">
            <td>{{book.id}}</td>
            <td>{{book.title}}</td>
            <td>{{book.author}}</td>
            <td>
                <button (click) = "updateBook(book.id)">Edit</button>      
                <button (click) = "deleteBook(book.id)">Delete</button>
            </td>
        </tr>
    </table>
</div>

book.service.ts

import { Injectable } from '@angular/core';
import { Http, Response, Headers, RequestOptions } from '@angular/http';
import { Observable } from 'rxjs';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';
import { Book } from './book';

@Injectable()
export class BookService{

    constructor(private _httpService: Http){}

    getAllBooks(): Observable<Book[]>{
        return this._httpService.get("http://localhost:8037/spring-mvc-restfull-crud-example/book")
                .map((response: Response) => response.json())
                .catch(this.handleError);
    }

    getBookById(bookId: string): Observable<Book>{
        console.log("Inside the getBookById() service::::::");
        return this._httpService.get("http://localhost:8037/spring-mvc-restfull-crud-example/book/"+bookId)
                .map((response: Response) => response.json())
                .catch(this.handleError);
    }

    addBook(book: Book){
        let headers = new Headers({ 'Content-Type': 'application/json' });
        let options = new RequestOptions({ headers: headers });
        if(book.id){    
            console.log("Inside addBook update service():::::::");
            return this._httpService.put("http://localhost:8037/spring-mvc-restfull-crud-example/book/"+book.id, JSON.stringify(book), options);
        }else{
            console.log("Inside addBook add service():::::::body:::::::"+JSON.stringify(book));
            return this._httpService.post("http://localhost:8037/spring-mvc-restfull-crud-example/book", JSON.stringify(book), options);
        }
    }

    deleteBook(bookId: string){
        console.log("Inside the service deleteBook():::::book id:::"+bookId);
        return this._httpService.delete("http://localhost:8037/spring-mvc-restfull-crud-example/book/"+bookId);  
    }

    private handleError(error: Response){
        console.error(error);
        return Observable.throw(error);
    }
}

app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { HttpModule } from '@angular/http';
import { FormsModule } from '@angular/forms';


import { AppComponent } from './app.component';
import { BookService } from './book/book.service';
import { BookComponent } from './book/book.component';


@NgModule({
  declarations: [
    AppComponent, BookComponent
  ],
  imports: [
    BrowserModule, HttpModule, FormsModule
  ],
  providers: [BookService],
  bootstrap: [AppComponent]
})
export class AppModule { }

我的代码出了什么问题？或者怎么做？在此先感谢：）

Answer 1

在subscribe函数中写 this.getBooks（），因为它以异步方式工作。

在角度2中插入新记录后不更新表数据

1 个答案: