dotnet-ef-core-configuration

# EF Core Configuration Generator

## Overview

This skill generates Entity Framework Core configurations using Fluent API:

- **IEntityTypeConfiguration<T>** - Per-entity configuration classes
- **Fluent API over attributes** - Keep domain clean
- **Snake case naming** - PostgreSQL convention
- **Relationships** - One-to-Many, Many-to-Many, One-to-One
- **Value Objects** - Owned types mapping

## Quick Reference

| Configuration | Use |
|---------------|-----|
| `ToTable()` | Table name |
| `HasKey()` | Primary key |
| `Property()` | Column configuration |
| `HasOne/HasMany()` | Relationships |
| `OwnsOne()` | Value objects |
| `HasIndex()` | Database indexes |

---

## Configuration Structure

```
/Infrastructure/Configurations/
├── {Entity}Configuration.cs
├── {ChildEntity}Configuration.cs
├── {ValueObject}Configuration.cs
└── OutboxMessageConfiguration.cs
```

---

## Template: Basic Entity Configuration

```csharp
// src/{name}.infrastructure/Configurations/{Entity}Configuration.cs
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using {name}.domain.{aggregate};

namespace {name}.infrastructure.configurations;

internal sealed class {Entity}Configuration : IEntityTypeConfiguration<{Entity}>
{
    public void Configure(EntityTypeBuilder<{Entity}> builder)
    {
        // ═══════════════════════════════════════════════════════════════
        // TABLE MAPPING
        // ═══════════════════════════════════════════════════════════════
        builder.ToTable("{entity}");  // snake_case table name

        // ═══════════════════════════════════════════════════════════════
        // PRIMARY KEY
        // ═══════════════════════════════════════════════════════════════
        builder.HasKey(e => e.Id);
        
        builder.Property(e => e.Id)
            .ValueGeneratedNever();  // App generates GUIDs

        // ═══════════════════════════════════════════════════════════════
        // PROPERTIES
        // ═══════════════════════════════════════════════════════════════
        builder.Property(e => e.Name)
            .HasMaxLength(100)
            .IsRequired();

        builder.Property(e => e.Description)
            .HasColumnType("text");  // Unlimited length

        builder.Property(e => e.IsActive)
            .HasDefaultValue(true)
            .IsRequired();

        builder.Property(e => e.CreatedAt)
            .IsRequired()
            .HasDefaultValueSql("CURRENT_TIMESTAMP AT TIME ZONE 'UTC'");

        builder.Property(e => e.UpdatedAt)
            .IsRequired()
            .HasDefaultValueSql("CURRENT_TIMESTAMP AT TIME ZONE 'UTC'");

        // ═══════════════════════════════════════════════════════════════
        // INDEXES
        // ═══════════════════════════════════════════════════════════════
        builder.HasIndex(e => e.Name)
            .IsUnique();

        builder.HasIndex(e => e.OrganizationId);

        builder.HasIndex(e => new { e.OrganizationId, e.Name })
            .IsUnique();
    }
}
```

---

## Template: Entity with Relationships

```csharp
// src/{name}.infrastructure/Configurations/{Entity}Configuration.cs
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using {name}.domain.{aggregate};

namespace {name}.infrastructure.configurations;

internal sealed class {Entity}Configuration : IEntityTypeConfiguration<{Entity}>
{
    public void Configure(EntityTypeBuilder<{Entity}> builder)
    {
        builder.ToTable("{entity}");
        builder.HasKey(e => e.Id);

        // ═══════════════════════════════════════════════════════════════
        // FOREIGN KEY PROPERTIES
        // ═══════════════════════════════════════════════════════════════
        builder.Property(e => e.OrganizationId)
            .IsRequired();

        builder.Property(e => e.ParentId);  // Nullable FK

        // ═══════════════════════════════════════════════════════════════
        // ONE-TO-MANY: Parent has many children
        // ═══════════════════════════════════════════════════════════════
        builder.HasMany(e => e.{ChildEntities})
            .WithOne(c => c.{Entity})
            .HasForeignKey(c => c.{Entity}Id)
            .OnDelete(DeleteBehavior.Cascade);

        // ═══════════════════════════════════════════════════════════════
        // MANY-TO-ONE: Entity belongs to Organization
        // ═══════════════════════════════════════════════════════════════
        builder.HasOne(e => e.Organization)
            .WithMany(o => o.{Entities})
            .HasForeignKey(e => e.OrganizationId)
            .OnDelete(DeleteBehavior.Restrict);  // Prevent cascade delete

        // ═══════════════════════════════════════════════════════════════
        // SELF-REFERENCING: Entity has optional parent
        // ═══════════════════════════════════════════════════════════════
        builder.HasOne(e => e.Parent)
            .WithMany(e => e.Children)
            .HasForeignKey(e => e.ParentId)
            .OnDelete(DeleteBehavior.Restrict)
            .IsRequired(false);
    }
}
```

---

## Template: Child Entity Configuration

```csharp
// src/{name}.infrastructure/Configurations/{ChildEntity}Configuration.cs
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using {name}.domain.{aggregate};

namespace {name}.infrastructure.configurations;

internal sealed class {ChildEntity}Configuration : IEntityTypeConfiguration<{ChildEntity}>
{
    public void Configure(EntityTypeBuilder<{ChildEntity}> builder)
    {
        builder.ToTable("{child_entity}");
        
        builder.HasKey(c => c.Id);
        
        builder.Property(c => c.Id)
            .ValueGeneratedNever();

        builder.Property(c => c.{Parent}Id)
            .IsRequired();

        builder.Property(c => c.Name)
            .HasMaxLength(100)
            .IsRequired();

        builder.Property(c => c.SortOrder)
            .IsRequired()
            .HasDefaultValue(0);