.NET Core Web API for Order Management

Introduction

In today's fast-paced world, real-time applications are critical for businesses. From stock tracking to e-commerce order management, the need for instant updates is ubiquitous. This blog demonstrates how to create a real-time Order Management System using .NET Core Web API, SignalR, and a simple Angular client.

1. Project Setup

Prerequisites

• Install .NET SDK (at least .NET 6.0).
• Install a database (e.g., SQL Server or SQLite).
• Install an IDE like Visual Studio or Visual Studio Code.
• Basic knowledge of C# and .NET Core.

Step 1: Create a New Web API Project

Run the following command to create a new Web API project:

bash
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dotnet new webapi -n OrderManagementApi

Navigate to the project directory:

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cd OrderManagementApi

Step 2: Add Necessary NuGet Packages

Install SignalR and Entity Framework Core:

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dotnet add package Microsoft.AspNetCore.SignalR
dotnet add package Microsoft.EntityFrameworkCore
dotnet add package Microsoft.EntityFrameworkCore.SqlServer
dotnet add package Microsoft.EntityFrameworkCore.Tools

2. Design the API

Models

Create a Models folder and add an Order class:

csharp
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public class Order
{
    public int Id { get; set; }
    public string ProductName { get; set; }
    public int Quantity { get; set; }
    public DateTime OrderDate { get; set; }
    public string Status { get; set; }
}

DbContext

Create an OrderContext class in a Data folder:

csharp
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using Microsoft.EntityFrameworkCore;

public class OrderContext : DbContext
{
    public OrderContext(DbContextOptions<OrderContext> options) : base(options) { }

    public DbSet<Order> Orders { get; set; }
}

Configure the database connection in appsettings.json:

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"ConnectionStrings": {
    "DefaultConnection": "Server=localhost;Database=OrderDB;Trusted_Connection=True;"
}

Update the Program.cs file to add DbContext:

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builder.Services.AddDbContext<OrderContext>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));

API Controllers

Add an OrdersController:

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[ApiController]
[Route("api/[controller]")]
public class OrdersController : ControllerBase
{
    private readonly OrderContext _context;

    public OrdersController(OrderContext context)
    {
        _context = context;
    }

    [HttpGet]
    public async Task<ActionResult<IEnumerable<Order>>> GetOrders()
    {
        return await _context.Orders.ToListAsync();
    }

    [HttpPost]
    public async Task<ActionResult<Order>> AddOrder(Order order)
    {
        _context.Orders.Add(order);
        await _context.SaveChangesAsync();
        return CreatedAtAction(nameof(GetOrders), new { id = order.Id }, order);
    }
}

3. Real-Time Updates with SignalR

Hub Configuration

Create an OrderHub class:

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using Microsoft.AspNetCore.SignalR;

public class OrderHub : Hub
{
    public async Task NotifyOrderCreated(Order order)
    {
        await Clients.All.SendAsync("OrderCreated", order);
    }
}

Register SignalR in Program.cs:

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builder.Services.AddSignalR();

app.MapHub<OrderHub>("/orderHub");

4. Angular Client for Real-Time Updates

Setup Angular Project

Install Angular CLI and create a new project:

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npm install -g @angular/cli
ng new order-management-client
cd order-management-client

Install SignalR client:

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npm install @microsoft/signalr

Service to Connect SignalR

Create an OrderService:

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import { Injectable } from '@angular/core';
import * as signalR from '@microsoft/signalr';

@Injectable({
  providedIn: 'root',
})
export class OrderService {
  private hubConnection: signalR.HubConnection;

  constructor() {
    this.hubConnection = new signalR.HubConnectionBuilder()
      .withUrl('https://localhost:5001/orderHub')
      .build();

    this.hubConnection.start().catch(err => console.error(err));
  }

  listenForNewOrders(callback: (order: any) => void) {
    this.hubConnection.on('OrderCreated', callback);
  }
}

5. Testing the API

• Use tools like Postman or Swagger to test API endpoints.
• Test real-time updates by adding a new order and observing live updates on the Angular client.

6. Deployment

• Host the .NET Core Web API on a cloud platform like Azure or AWS.
• Deploy the Angular client on a platform like Netlify or Firebase.