AgentSkillsCN

add-entity

为新的领域实体构建值对象 ID、聚合根、工厂方法，以及领域事件。

SKILL.md
--- frontmatter
name: add-entity
description: Scaffold a new domain entity with value object ID, aggregate root, factory method, and domain event
allowed-tools: Read, Write, Edit, Glob, Grep, Bash

Add Domain Entity

When the user asks to add a new entity, scaffold following the project's domain-driven design patterns.

1. Value Object ID (Domain/ValueObjects/{Entity}Id.cs)

csharp
namespace SignalBeam.Domain.ValueObjects;

public class {Entity}Id : ValueObject
{
    public Guid Value { get; init; }

    public {Entity}Id(Guid value)
    {
        if (value == Guid.Empty)
            throw new ArgumentException("{Entity}Id cannot be empty.", nameof(value));
        Value = value;
    }

    public static {Entity}Id New() => new(Guid.NewGuid());

    protected override IEnumerable<object?> GetEqualityComponents()
    {
        yield return Value;
    }
}

2. Entity / Aggregate Root (Domain/Entities/{Entity}.cs)

csharp
namespace SignalBeam.Domain.Entities;

public class {Entity} : AggregateRoot<{Entity}Id>
{
    public TenantId TenantId { get; private set; }
    // Add properties with private setters

    // EF Core constructor
    protected {Entity}() : base(default!) { }

    // Private constructor called by factory method
    private {Entity}({Entity}Id id, TenantId tenantId, ...) : base(id)
    {
        TenantId = tenantId;
        // Set properties
    }

    // Factory method - the ONLY way to create instances
    public static {Entity} Create(TenantId tenantId, ...)
    {
        var id = {Entity}Id.New();
        var entity = new {Entity}(id, tenantId, ...);
        entity.RaiseDomainEvent(new {Entity}CreatedEvent(id, tenantId, DateTimeOffset.UtcNow));
        return entity;
    }

    // State-changing methods raise domain events
    public void Update(...)
    {
        // Modify state
        RaiseDomainEvent(new {Entity}UpdatedEvent(Id, ...));
    }
}

3. Domain Event (Domain/Events/{Entity}CreatedEvent.cs)

csharp
namespace SignalBeam.Domain.Events;

public class {Entity}CreatedEvent : DomainEvent
{
    public {Entity}Id {Entity}Id { get; }
    public TenantId TenantId { get; }
    public DateTimeOffset OccurredAt { get; }

    public {Entity}CreatedEvent({Entity}Id entityId, TenantId tenantId, DateTimeOffset occurredAt)
    {
        {Entity}Id = entityId;
        TenantId = tenantId;
        OccurredAt = occurredAt;
    }
}

4. Repository Interface (Domain/ or Application/)

csharp
public interface I{Entity}Repository
{
    Task<{Entity}?> GetByIdAsync({Entity}Id id, CancellationToken cancellationToken = default);
    Task AddAsync({Entity} entity, CancellationToken cancellationToken = default);
    Task SaveChangesAsync(CancellationToken cancellationToken = default);
}

public interface I{Entity}QueryRepository
{
    Task<{Entity}?> GetByIdAsync({Entity}Id id, CancellationToken cancellationToken = default);
    Task<(IReadOnlyCollection<{Entity}> Items, int TotalCount)> ListAsync(TenantId tenantId, int page, int pageSize, CancellationToken cancellationToken = default);
}

5. EF Core Configuration (Infrastructure/Persistence/Configurations/{Entity}Configuration.cs)

csharp
public class {Entity}Configuration : IEntityTypeConfiguration<{Entity}>
{
    public void Configure(EntityTypeBuilder<{Entity}> builder)
    {
        builder.HasKey(x => x.Id);
        builder.Property(x => x.Id)
            .HasConversion(id => id.Value, value => new {Entity}Id(value));
        builder.Property(x => x.TenantId)
            .HasConversion(id => id.Value, value => new TenantId(value));
        // Configure other properties
    }
}

6. Add DbSet to DbContext

csharp
public DbSet<{Entity}> {Entity}s => Set<{Entity}>();

Checklist

  • • Value object ID with validation and GetEqualityComponents()
  • • Entity inherits AggregateRoot<TId> with protected parameterless constructor
  • • Factory method is the only creation path
  • • Domain events raised in factory and state-change methods
  • • Past-tense event names: {Entity}CreatedEvent, {Entity}UpdatedEvent
  • • Separate command and query repository interfaces
  • • EF Core configuration with value object conversions
  • • DbSet added to DbContext
  • • No framework dependencies in Domain layer