What I've Learned about LINQ and MVC

What I’ve Learned about LINQ and MVC

Learning about C# and the various facets of MVC architecture has been exciting.

I am sharing an example of why using LINQ with Lambdas is quickly becoming my favorite feature in C#.

The Situation

Allow me to lay out this hypothetical for you:

You’re setting up a complex front end with specific business requirements.

You have a model representing a table of products in your database.

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

With LINQ and Lambdas, you gain an idiomatic abstraction over SQL queries that is both straightforward and powerful.

Business logic with becomes easy to define and maintain—structured in a familiar way to SQL when using LINQ.

In our example below, we can address the business requirements in a declarative fashion, reducing the need for maintenance and limiting the introduction of bugs.

Need a list of products with a stock greater than 5 but ordered by the cheapest price?

Simple with Lambdas and LINQ:

.Where(p => p.Stock > 5) 

.OrderBy(p => p.Price)

.ToList();

Full Controller Class

public class ProductsController : Controller
{
    private readonly AppDbContext _context;

    public ProductsController(AppDbContext context)
    {
        _context = context;
    }

    public IActionResult Index()
    {
        // Fetch all products
        var products = _context.Products.ToList();
        
        // Filter products with Price < 2
        var productsToRemove = products.Where(p => p.Price < 2)
        							   .ToList();

        // Remove each filtered product from the database
        _context.Products.RemoveRange(productsToRemove);

        // Save changes to persist the removal
        _context.SaveChanges();
        
        // Fetch a specific product by name
        var laptop = _context.Products.FirstOrDefault(p => p.Name == "Laptop");

        // Fetch products with stock greater than 5, ordered by cheapest price
        var inStock = _context.Products
                              .Where(p => p.Stock > 5)
                              .OrderBy(p => p.Price)
                              .ToList();
                              
        // Fetch up to 10 products named "Laptop"
        var laptops = _context.Products
                              .Where(p => p.Name == "Laptop")
                              .Take(10)
                              .ToList();
		
        // Pass the data to the view
        return View(products);
    }
}

Conclusion

Instead of writing verbose SQL queries or manually iterating through collections, LINQ with Lambdas allows us to express business logic concisely.