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🎞 ANIMATE · Mode 3 of 5 · +100 XP— Clean Architecture
📋Domain
⚙️Application
🔄Infrastructure
✅DI
🎯 Next: Test →
Step 1 / 4
Speed
Domain Layer
Domain entities contain business rules — zero external dependencies💡 Analogy
Like the core of an onion — the centre has no dependencies but everything depends on it.
The Domain layer is the innermost ring. It contains entities, value objects, and domain logic. It has NO imports from external packages.
Console Output
> Order.cs: 0 external package references
> Business rule enforced: "Cannot modify confirmed order"
> Domain exception thrown on violation
●CleanArchitecture.cs
Domain LayerL1–14
1// Domain Layer — no dependencies, pure business logic
2namespace Domain.Entities;
3public class Order
4{
5    public Guid Id { get; private set; } = Guid.NewGuid();
6    public List<OrderItem> Items { get; private set; } = new();
7    public OrderStatus Status { get; private set; } = OrderStatus.Pending;
8 
9    public void AddItem(Product product, int quantity)
10    {
11        if (Status != OrderStatus.Pending)
12            throw new DomainException("Cannot modify confirmed order");
13        Items.Add(new OrderItem(product, quantity));
14    }
15}
16 
17// Application Layer — orchestrates domain, depends only on Domain
18namespace Application.UseCases;
19public class PlaceOrderHandler : IRequestHandler<PlaceOrderCommand, Guid>
20{
21    private readonly IOrderRepository _orders;
22    private readonly IEventBus _eventBus;
23 
24    public async Task<Guid> Handle(PlaceOrderCommand cmd, CancellationToken ct)
25    {
26        var order = new Order();
27        foreach (var item in cmd.Items)
28            order.AddItem(item.Product, item.Quantity);
29 
30        await _orders.SaveAsync(order, ct);
31        await _eventBus.PublishAsync(new OrderPlacedEvent(order.Id), ct);
32        return order.Id;
33    }
34}
35 
36// Infrastructure Layer — implements interfaces from Application
37namespace Infrastructure.Persistence;
38public class OrderRepository : IOrderRepository
39{
40    private readonly AppDbContext _db;
41    public async Task SaveAsync(Order order, CancellationToken ct)
42        => await _db.Orders.AddAsync(order, ct).AsTask()
43            .ContinueWith(_ => _db.SaveChangesAsync(ct));
44}
44 lines
Timeline — 4 Steps
Domain Layer
Domain entities contain business rules — zero external dependencies💡 Analogy
Like the core of an onion — the centre has no dependencies but everything depends on it.
The Domain layer is the innermost ring. It contains entities, value objects, and domain logic. It has NO imports from external packages.
Console Output
> Order.cs: 0 external package references
> Business rule enforced: "Cannot modify confirmed order"
> Domain exception thrown on violation

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Discussion

Domain entities contain business rules — zero external dependencies

💡 Analogy

Like the core of an onion — the centre has no dependencies but everything depends on it.

The Domain layer is the innermost ring. It contains entities, value objects, and domain logic. It has NO imports from external packages.

Console Output

> Order.cs: 0 external package references
> Business rule enforced: "Cannot modify confirmed order"
> Domain exception thrown on violation

Domain entities contain business rules — zero external dependencies

💡 Analogy

Like the core of an onion — the centre has no dependencies but everything depends on it.

The Domain layer is the innermost ring. It contains entities, value objects, and domain logic. It has NO imports from external packages.

Console Output

> Order.cs: 0 external package references
> Business rule enforced: "Cannot modify confirmed order"
> Domain exception thrown on violation