In the first part of this tutorial series, you learned how to get started creating an Angular web application. You learned how to set up the application and create the login component.
In this part of the series, you will further write about the REST API required to interact with the banking side of MongoDB. You will also create theHomecomponent, which will be displayed after the user successfully logs in.
start using
Let's start by cloning the source code for the first part of this tutorial series.
git clone https://github.com/royagasthyan/AngularBlogApp-Login AngularBlogApp-Home
Navigate to the project directory and install the required dependencies.
cd AngularBlogApp-Home/client npm install
After installing the dependencies, restart the application server.
npm start
Point your browser to http://localhost:4200 and the application should be running.
Create Login REST API
In the project folderAngularBlogApp-Home, create another folder namedserver. You'll write a REST API using Node.js.
Navigate to theserverfolder and initialize the project.
cd server npm init
Enter the required details and you should have your project initialized.
You will use theExpressframework to create the server. InstallExpressusing the following command:
npm install express --save
After installingExpress, create a file namedapp.js. This will be the root file of the Node.js server.
Here is what theapp.jsfile looks like:
const express = require('express') const app = express() app.get('/api/user/login', (req, res) => { res.send('Hello World!') }) app.listen(3000, () => console.log('blog server running on port 3000!'))
As shown in the code above, you importexpressintoapp.js. Usingexpress, you create an applicationapp.
Withapp, you expose an endpoint/api/user/loginwhich will display a message. Start the Node.js server using the following command:
node app.js
Point your browser to http://localhost:3000/api/user/login and you should see the message.
You will make aPOSTrequest from the Angular service to the server using theUsernameandPasswordparameters. So the request parameters need to be parsed.
Installationbody-parser, this is Node.js body parsing middleware, used to parse request parameters.
npm install body-parser --save
After the installation is complete, import it intoapp.js.
const bodyParser = require('body-parser')
Add the following code to theapp.jsfile.
app.use(bodyParser.json()) app.use(bodyParser.urlencoded({ extended : false}))
The twobody-parseroptions above return middleware that only parsesjsonandurlencodedbodies, and only looks atContent-TypeHeaders matching requesttypeoptions.
You will useMongooseto interact withMongoDBin Node.js. Therefore, installMongooseusing Node Package Manager (npm).
npm install mongoose --save
After installing mongoose, import it intoapp.js.
const mongoose = require('mongoose');
Define the MongoDB database URL inapp.js.
const url = 'mongodb://localhost/blogDb';
Let’s connect to the MongoDB database usingMongoose. Its appearance is as follows:
app.post('/api/user/login', (req, res) => { mongoose.connect(url, function(err){ if(err) throw err; console.log('connected successfully, username is ',req.body.username,' password is ',req.body.password); }); })
If a connection is established, the message will be logged along with theusernameandpassword.
Here is what theapp.jsfile looks like:
const express = require('express') const bodyParser = require('body-parser') const app = express() const mongoose = require('mongoose'); const url = 'mongodb://localhost/blogDb'; app.use(bodyParser.json()) app.use(bodyParser.urlencoded({ extended : false})) app.post('/api/user/login', (req, res) => { mongoose.connect(url, function(err){ if(err) throw err; console.log('connected successfully, username is ',req.body.username,' password is ',req.body.password); }); }) app.listen(3000, () => console.log('blog server running on port 3000!'))
Restart the node server using the following command:
node app.js
To connect to a Node server from an Angular application, you need to set up a proxy. Create a file namedproxy.jsonin theclient/srcfolder. Its appearance is as follows:
{ "/api/*": { "target": "http://localhost:3000", "secure": "false" } }
Modify the clientpackage.jsonfile to use the proxy file to launch the application.
"start": "ng serve --proxy-config proxy.json"
Save changes and start the client server.
npm start
Point your browser to http://localhost:4200 and enter your username and password. Click the login button and you should log the parameters into the node console.
Verify user login
To use Mongoose to interact with MongoDB, you need to define the schema and create a model. Within theserverfolder, create a folder namedmodel.
Create a file nameduser.jsin themodelfolder. Add the following code to theuser.jsfile:
const mongoose = require('mongoose'); const Schema = mongoose.Schema; // create a schema const userSchema = new Schema({ username: { type: String, required: true, unique: true }, password: { type: String, required: true }, name: { type: String } }, { collection : 'user' }); const User = mongoose.model('User', userSchema); module.exports = User;
As shown in the code above, you import mongoose intouser.js. You created theuserSchemausing mongooseschemaand theUsermodel using themongoosemodel.
将user.js文件导入到app.js文件中。
const User = require('./model/user');
在查询 MongoDBuser集合之前，您需要创建该集合。输入mongo转到 MongoDB shell。使用以下命令创建集合user：
db.createCollection('user')
插入您要查询的记录。
db.user.insert({ name: 'roy agasthyan', username: 'roy', password: '123' })
现在，一旦 mongoose 连接到 MongoDB，您将使用传入的用户名和密码从数据库中找到记录。API 如下所示：
app.post('/api/user/login', (req, res) => { mongoose.connect(url,{ useMongoClient: true }, function(err){ if(err) throw err; User.find({ username : req.body.username, password : req.body.password }, function(err, user){ if(err) throw err; if(user.length === 1){ return res.status(200).json({ status: 'success', data: user }) } else { return res.status(200).json({ status: 'fail', message: 'Login Failed' }) } }) }); })
如上面的代码所示，一旦收到数据库的响应，就会将其返回给客户端。
保存以上更改并尝试运行客户端和服务器。输入用户名roy和密码123，您应该能够在浏览器控制台中查看结果。
重定向到主页组件
用户验证成功后，您需要将用户重定向到Home组件。因此，让我们首先创建Home组件。
在src/app文件夹中创建一个名为Home的文件夹。创建一个名为home.component.html的文件并添加以下 HTML 代码：
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创建一个名为home.component.css的文件并添加以下 CSS 样式：
.header, .marketing, .footer { padding-right: 1rem; padding-left: 1rem; } /* Custom page header */ .header { padding-bottom: 1rem; border-bottom: .05rem solid #e5e5e5; } .header h3 { margin-top: 0; margin-bottom: 0; line-height: 3rem; } /* Custom page footer */ .footer { padding-top: 1.5rem; color: #777; border-top: .05rem solid #e5e5e5; } /* Customize container */ @media (min-width: 48em) { .container { max-width: 46rem; } } .container-narrow > hr { margin: 2rem 0; } /* Main marketing message and sign up button */ .jumbotron { text-align: center; border-bottom: .05rem solid #e5e5e5; } .jumbotron .btn { padding: .75rem 1.5rem; font-size: 1.5rem; } /* Supporting marketing content */ .marketing { margin: 3rem 0; } .marketing p + h4 { margin-top: 1.5rem; } /* Responsive: Portrait tablets and up */ @media screen and (min-width: 48em) { /* Remove the padding we set earlier */ .header, .marketing, .footer { padding-right: 0; padding-left: 0; } /* Space out the masthead */ .header { margin-bottom: 2rem; } .jumbotron { border-bottom: 0; } }
创建名为home.component.ts的组件文件并添加以下代码：
import { Component } from '@angular/core'; @Component({ selector: 'app-home', templateUrl: './home.component.html', styleUrls: ['./home.component.css'] }) export class HomeComponent { }
如上面的代码所示，您刚刚使用@Component装饰器创建了HomeComponent并指定了选择器,templateUrl和styleUrls。
将HomeComponent添加到NgModules中的app.module.ts。
import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; import { ROUTING } from './app.routing'; import { FormsModule } from '@angular/forms'; import { HttpClientModule } from '@angular/common/http'; import { RootComponent } from './root/root.component'; import { LoginComponent } from './login/login.component'; import { HomeComponent } from './home/home.component'; @NgModule({ declarations: [ RootComponent, LoginComponent, HomeComponent ], imports: [ BrowserModule, ROUTING, FormsModule, HttpClientModule ], providers: [], bootstrap: [RootComponent] }) export class AppModule { }
在app.routing.ts中导入HomeComponent，并为home定义路由。
import { RouterModule, Routes } from '@angular/router'; import { ModuleWithProviders } from '@angular/core/src/metadata/ng_module'; import { LoginComponent } from './login/login.component'; import { HomeComponent } from './home/home.component'; export const AppRoutes: Routes = [ { path: '', component: LoginComponent }, { path: 'home', component: HomeComponent } ]; export const ROUTING: ModuleWithProviders = RouterModule.forRoot(AppRoutes);
在login.component.ts文件中的validateLogin方法中，成功验证后会将用户重定向到HomeComponent。要重定向，您需要导入 AngularRouter。
import { Router } from '@angular/router';
如果 API 调用的响应成功，您将使用 AngularRouter导航到HomeComponent。
if(result['status'] === 'success') { this.router.navigate(['/home']); } else { alert('Wrong username password'); }
以下是login.component.ts文件的外观：
import { Component } from '@angular/core'; import { LoginService } from './login.service'; import { User } from '../models/user.model'; import { Router } from '@angular/router'; @Component({ selector: 'app-login', templateUrl: './login.component.html', styleUrls: ['./login.component.css'], providers: [ LoginService ] }) export class LoginComponent { public user : User; constructor(private loginService: LoginService, private router: Router) { this.user = new User(); } validateLogin() { if(this.user.username && this.user.password) { this.loginService.validateLogin(this.user).subscribe(result => { console.log('result is ', result); if(result['status'] === 'success') { this.router.navigate(['/home']); } else { alert('Wrong username password'); } }, error => { console.log('error is ', error); }); } else { alert('enter user name and password'); } } }
保存以上更改并重新启动服务器。使用现有的用户名和密码登录应用程序，您将被重定向到HomeComponent。
总结
在本教程中，您了解了如何编写用于用户登录的 REST API 端点。您学习了如何使用Mongoose从 Node.js 与 MongoDB 进行交互。成功验证后，您了解了如何使用 AngularRouter导航到HomeComponent。
您学习编写 Angular 应用程序及其后端的体验如何？请在下面的评论中告诉我们您的想法和建议。
本教程的源代码可在 GitHub 上获取。
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