EF Core CRUD Operations - .NET Core Samples

Performing CRUD Operations with EF Core

This guide demonstrates how to perform the fundamental Create, Read, Update, and Delete (CRUD) operations using Entity Framework Core in a .NET Core application. EF Core simplifies data access by allowing you to work with your database using .NET objects.

1. Setting Up the DbContext and Models

First, ensure you have your data models defined and a DbContext that represents your database session.

Model Definition (e.g., Product.cs)

public class Product
{
    public int ProductId { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
    public int Stock { get; set; }
}

DbContext Definition (e.g., AppDbContext.cs)

using Microsoft.EntityFrameworkCore;

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

    public DbSet<Product> Products { get; set; }

    // Configure your database provider and connection string in Startup.cs or appsettings.json
}

Create Read Update Delete

2. Creating (Adding) a New Record

To add a new entity, create an instance of your model, attach it to the DbContext, and save the changes.

C# Code

using (var context = new AppDbContext(/* options */))
{
    var newProduct = new Product
    {
        Name = "Wireless Mouse",
        Price = 25.99m,
        Stock = 150
    };

    context.Products.Add(newProduct); // Or context.Add(newProduct);
    await context.SaveChangesAsync(); // Saves changes to the database

    Console.WriteLine($"Product added with ID: {newProduct.ProductId}");
}

3. Reading (Querying) Records

You can query records using LINQ to query your DbSet.

Get All Products

using (var context = new AppDbContext(/* options */))
{
    var allProducts = await context.Products.ToListAsync();
    foreach (var product in allProducts)
    {
        Console.WriteLine($"- {product.Name} (Price: {product.Price:C}, Stock: {product.Stock})");
    }
}

Get a Specific Product by ID

using (var context = new AppDbContext(/* options */))
{
    int productIdToFind = 1; // Example ID
    var product = await context.Products.FindAsync(productIdToFind);

    if (product != null)
    {
        Console.WriteLine($"Found Product: {product.Name}");
    }
    else
    {
        Console.WriteLine($"Product with ID {productIdToFind} not found.");
    }
}

Querying with Filters

using (var context = new AppDbContext(/* options */))
{
    // Find products with stock less than 50
    var lowStockProducts = await context.Products
                                        .Where(p => p.Stock < 50)
                                        .ToListAsync();

    Console.WriteLine("Low Stock Products:");
    foreach (var product in lowStockProducts)
    {
        Console.WriteLine($"- {product.Name} (Stock: {product.Stock})");
    }
}

4. Updating a Record

To update an existing entity, fetch it, modify its properties, and then save the changes.

C# Code

using (var context = new AppDbContext(/* options */))
{
    int productIdToUpdate = 1; // Example ID
    var productToUpdate = await context.Products.FindAsync(productIdToUpdate);

    if (productToUpdate != null)
    {
        productToUpdate.Price = 29.95m; // Update price
        productToUpdate.Stock += 20;   // Update stock

        // EF Core tracks changes to entities that are being tracked.
        // No need to explicitly call context.Update(productToUpdate) if it's already tracked.
        await context.SaveChangesAsync();

        Console.WriteLine($"Product '{productToUpdate.Name}' updated.");
    }
    else
    {
        Console.WriteLine($"Product with ID {productIdToUpdate} not found for update.");
    }
}

5. Deleting a Record

To delete an entity, fetch it, then mark it for deletion and save the changes.

C# Code

using (var context = new AppDbContext(/* options */))
{
    int productIdToDelete = 2; // Example ID
    var productToDelete = await context.Products.FindAsync(productIdToDelete);

    if (productToDelete != null)
    {
        context.Products.Remove(productToDelete); // Or context.Remove(productToDelete);
        await context.SaveChangesAsync();

        Console.WriteLine($"Product '{productToDelete.Name}' deleted.");
    }
    else
    {
        Console.WriteLine($"Product with ID {productIdToDelete} not found for deletion.");
    }
}