MongoDB With Angular Sample
Connecting MongoDB with an Express backend and an Angular frontend involves several steps. Here's a detailed guide, including a code sample, input/output, and steps.

Step 1. Set Up MongoDB
Install MongoDB

• Install MongoDB locally or use a cloud solution like MongoDB Atlas.
• Start the MongoDB server.

Create a Database

• Use the MongoDB shell or a GUI tool like MongoDB Compass to create a database, e.g., my_database.
• Add a collection, e.g., users.

Step 2. Create an Express Backend
Initialize the Project
mkdir express-mongodb-app
cd express-mongodb-app
npm init -y
npm install express mongoose body-parser cors

Create the Server File: Create a file named server.js.
const express = require('express');
const mongoose = require('mongoose');
const bodyParser = require('body-parser');
const cors = require('cors');
const app = express();

// Middleware
app.use(cors());
app.use(bodyParser.json());

// MongoDB Connection
mongoose.connect('mongodb://localhost:27017/my_database', {
    useNewUrlParser: true,
    useUnifiedTopology: true,
}).then(() => console.log("MongoDB connected"))
  .catch(err => console.error(err));

// Define Schema and Model
const userSchema = new mongoose.Schema({
    name: String,
    email: String,
});
const User = mongoose.model('User', userSchema);
// Routes
app.get('/api/users', async (req, res) => {
    const users = await User.find();
    res.json(users);
});
app.post('/api/users', async (req, res) => {
    const newUser = new User(req.body);
    await newUser.save();
    res.status(201).json(newUser);
});
// Start Server
const PORT = 3000;
app.listen(PORT, () => {
    console.log(`Server running on http://localhost:${PORT}`);
});

Run the Server
node server.js

Step 3. Create the Angular Frontend

Set Up Angular Project
ng new angular-mongodb-app
cd angular-mongodb-app
ng add @angular/material
npm install axios

Service for API Communication: Create a file src/app/services/user.service.ts.
import { Injectable } from '@angular/core';
import axios from 'axios';
@Injectable({
    providedIn: 'root'
})
export class UserService {
    private baseUrl = 'http://localhost:3000/api/users';
    getUsers() {
        return axios.get(this.baseUrl);
    }
    addUser(user: { name: string; email: string }) {
        return axios.post(this.baseUrl, user);
    }
}

Component for User Interaction: Update src/app/app.component.ts.

typescript
import { Component, OnInit } from '@angular/core';
import { UserService } from './services/user.service';

@Component({
    selector: 'app-root',
    template: `
        <div style="text-align: center;">
            <h1>Angular with Express & MongoDB</h1>
            <form (submit)="addUser($event)">
                <input type="text" [(ngModel)]="name" placeholder="Name" name="name" required>
                <input type="email" [(ngModel)]="email" placeholder="Email" name="email" required>
                <button type="submit">Add User</button>
            </form>
            <ul>
                <li *ngFor="let user of users">{{ user.name }} ({{ user.email }})</li>
            </ul>
        </div>
    `,
    styles: []
})
export class AppComponent implements OnInit {
    users: any[] = [];
    name = '';
    email = '';

    constructor(private userService: UserService) {}

    ngOnInit() {
        this.loadUsers();
    }

    async loadUsers() {
        const response = await this.userService.getUsers();
        this.users = response.data;
    }

    async addUser(event: Event) {
        event.preventDefault();
        await this.userService.addUser({ name: this.name, email: this.email });
        this.loadUsers();
        this.name = '';
        this.email = '';
    }
}

Install Angular Forms Module: Add FormsModule to AppModule.
typescript
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
@NgModule({
    declarations: [AppComponent],
    imports: [BrowserModule, FormsModule],
    providers: [],
    bootstrap: [AppComponent]
})
export class AppModule {}

Run the Angular Application
ng serve

Step 4. Input and Output
Input
Fill the form with a name and email, e.g.
Name: "Peter Scott"
Email: "[email protected]"

Output: The list below the form will update to include the newly added user.

less
Peter Scott ([email protected])

Step 5. Visual Workflow (Images)
Backend (server.js)

• Database schema for storing user data.
• APIs (/api/users) for CRUD operations.

Frontend (Angular App)

• The user fills out the form.
• Data is sent to the Express backend.
• Data is saved in MongoDB.
• Users are displayed dynamically.