CRUD operations (Create, Read, Update, Delete) are fundamental to any web application that interacts with a database. In ASP.NET MVC, you can implement these operations using a combination of models, views, and controllers. This guide will walk you through the process of implementing CRUD operations in an ASP.NET MVC application with sample code.

Step 1: Create a Model Class

First, you need to create a model class that represents the data structure you want to work with. Below is an example of a simple model class named Product:

        
        public class Product
        {
            public int Id { get; set; } // Unique identifier for the product
            public string Name { get; set; } // Name of the product
            public decimal Price { get; set; } // Price of the product
        }
            

Step 2: Create a Database Context

Next, create a database context class that inherits from DbContext. This class will manage the connection to the database and the entity objects. Below is an example of a context class named ApplicationDbContext:

        
        using System.Data.Entity;

        public class ApplicationDbContext : DbContext
        {
            public ApplicationDbContext() : base("DefaultConnection") // Connection string name
            {
            }

            public DbSet<Product> Products { get; set; } // DbSet for Product entities
        }
            

Step 3: Configure the Connection String

Define a connection string in the Web.config file of your ASP.NET MVC project. Below is an example of a connection string for a SQL Server database:

        
        <connectionStrings>
            <add name="DefaultConnection" 
                 connectionString="Server=YOUR_SERVER_NAME;Database=YOUR_DATABASE_NAME;Trusted_Connection=True;" 
                 providerName="System.Data.SqlClient" />
        </connectionStrings>
            

Replace YOUR_SERVER_NAME and YOUR_DATABASE_NAME with your actual SQL Server instance and database name.

Step 4: Create a Controller

Create a controller that will handle the CRUD operations. Below is an example of a controller named ProductController:

        
        using System.Collections.Generic;
        using System.Linq;
        using System.Web.Mvc;

        public class ProductController : Controller
        {
            private ApplicationDbContext db = new ApplicationDbContext();

            // GET: Product
            public ActionResult Index()
            {
                var products = db.Products.ToList(); // Retrieve all products from the database
                return View(products); // Pass the list of products to the view
            }

            // GET: Product/Create
            public ActionResult Create()
            {
                return View();
            }

            // POST: Product/Create
            [HttpPost]
            [ValidateAntiForgeryToken]
            public ActionResult Create(Product product)
            {
                if (ModelState.IsValid)
                {
                    db.Products.Add(product); // Add the new product to the context
                    db.SaveChanges(); // Save changes to the database
                    return RedirectToAction("Index"); // Redirect to the index action
                }
                return View(product); // Return the view with validation errors
            }

            // GET: Product/Edit/5
            public ActionResult Edit(int id)
            {
                var product = db.Products.Find(id); // Find the product by id
                if (product == null)
                {
                    return HttpNotFound(); // Return 404 if not found
                }
                return View(product); // Pass the product to the view
            }

            // POST: Product/Edit/5
            [HttpPost]
            [ValidateAntiForgeryToken]
            public ActionResult Edit(Product product)
            {
                if (ModelState.IsValid)
                {
                    db.Entry(product).State = EntityState.Modified; // Mark the product as modified
                    db.SaveChanges(); // Save changes to the database
                    return RedirectToAction("Index"); // Redirect to the index action
                }
                return View(product); // Return the view with validation errors
            }

            // GET: Product/Delete/5
            public Action Result Delete(int id)
            {
                var product = db.Products.Find(id); // Find the product by id
                if (product == null)
                {
                    return HttpNotFound(); // Return 404 if not found
                }
                return View(product); // Pass the product to the view
            }

            // POST: Product/Delete/5
            [HttpPost, ActionName("Delete")]
            [ValidateAntiForgeryToken]
            public ActionResult DeleteConfirmed(int id)
            {
                var product = db.Products.Find(id); // Find the product by id
                db.Products.Remove(product); // Remove the product from the context
                db.SaveChanges(); // Save changes to the database
                return RedirectToAction("Index"); // Redirect to the index action
            }
        }
            

Step 5: Create Views

You need to create views for each action in the controller. Below is an example of the Index view that displays the list of products:

        
        @model IEnumerable<YourNamespace.Models.Product>

        <h2>Products</h2>

        <p>
            <@Html.ActionLink("Create New", "Create")>
        </p>

        <table class="table">
            <tr>
                <th>@Html.DisplayNameFor(model => model.First().Name)</th>
                <th>@Html.DisplayNameFor(model => model.First().Price)</th>
                <th>@Html.DisplayName("Actions")</th>
            </tr>

            @foreach (var item in Model)
            {
                <tr>
                    <td>@Html.DisplayFor(modelItem => item.Name)</td>
                    <td>@Html.DisplayFor(modelItem => item.Price)</td>
                    <td>
                        <@Html.ActionLink("Edit", "Edit", new { id = item.Id })> |
                        <@Html.ActionLink("Delete", "Delete", new { id = item.Id })>
                    </td>
                </tr>
            }
        </table>
            

Conclusion

Implementing CRUD operations in ASP.NET MVC is straightforward with the use of models, views, and controllers. By following the steps outlined above, you can create a fully functional application that allows users to manage data effectively. This structure not only promotes clean code but also enhances maintainability and scalability of your application.