Why should you care?

ShopNest OrderService should not embed EF queries in every method if you want tests and storage flexibility.

See it live — copy this example

Paste into a C# console or class library project and run dotnet run.

public interface IOrderRepository
{
    Task<Order?> GetAsync(Guid id);
    Task AddAsync(Order order);
}
public sealed class Order
{
    public Guid Id { get; init; } = Guid.NewGuid();
    public string Sku { get; init; } = "";
}
public sealed class InMemoryOrderRepository : IOrderRepository
{
    private readonly Dictionary<Guid, Order> _db = new();
    public Task<Order?> GetAsync(Guid id) => Task.FromResult(_db.TryGetValue(id, out var o) ? o : null);
    public Task AddAsync(Order order) { _db[order.Id] = order; return Task.CompletedTask; }
}

var repo = new InMemoryOrderRepository();
var order = new Order { Sku = "HD-100" };
await repo.AddAsync(order);
Console.WriteLine((await repo.GetAsync(order.Id))!.Sku);

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

What happened?

• IOrderRepository hides storage.
• In-memory impl powers tests; EF impl used in prod.
• Avoid generic repositories that leak IQueryable everywhere.

Practice next

1. Add and get an order.
2. Write a fake for a unit test.
3. Add FindBySkuAsync on the interface.
4. Throw if duplicate id on Add.
5. List all orders method.

Remember

Collection-like persistence port. Swap impls for tests. Model aggregates.

ShopNest order repository

Handlers depend on IOrderRepository.

Outcome: EF changes stay in infrastructure.