Simplify DbContext by extracting aggregate configuration into dedicat…

…ed classes (#676)

### Summary & Motivation

Remove the need for centralized configuration in the `DbContext` when
defining aggregates in a self-contained system. Previously, the
`DbContext` required a `DbSet<T>` property for each aggregate (table)
and explicit configuration in `OnModelCreating` for strongly typed IDs
and other EF configurations like `.HasOne<T>()`, `.WithMany()`,
`.OnDelete()`, `.ToJson()`, etc. Over time, this made the `DbContext` in
a self-contained system big and hard to maintain

With this change, all entity configurations are moved to dedicated
classes implementing `IEntityTypeConfiguration<T>`, keeping each
aggregate's configuration within its vertical slice. The
`SharedKernelDbContext` now automatically discovers and registers these
configurations, eliminating the need for central configuration.

Additionally, the `DbContext` now uses a convention-based approach to
create tables, leveraging Humanizer for pluralizing table names. This
removes the need to define `DbSet<T>` properties explicitly, making the
`DbContext` a lightweight class used only in repositories without
requiring customization for new aggregates.

### Downstream Projects

Extract an `AggregateConfiguration` file for each aggregate, where the
content should match the current configuration in `OnModelCreating` in
the self-contained system’s `DbContext`. Example:

```csharp
namespace PlatformPlatform.AccountManagement.Features.Signups.Domain;

public sealed class SignupConfiguration : IEntityTypeConfiguration<Signup>
{
    public void Configure(EntityTypeBuilder<Signup> builder)
    {
        builder.MapStronglyTypedUuid<Signup, SignupId>(a => a.Id);
        builder.MapStronglyTypedNullableId<Signup, TenantId, string>(u => u.TenantId);
    }
}
```

All properties for tables should be removed from DbContext. Any direct
usage of these should be replaced by DbSet<T> in the repository.
Example:

```csharp
// Before:
return accountManagementDbContext.Signups.Where(s => ...);

// After:
return DbSet.Where(s => ...);
```

### Checklist

- [x] I have added tests, or done manual regression tests
- [x] I have updated the documentation, if necessary

application/Directory.Packages.props

@@ -21,6 +21,7 @@
     <PackageVersion Include="Bogus" Version="35.6.1" />
     <PackageVersion Include="FluentAssertions" Version="6.12.2" />
     <PackageVersion Include="FluentValidation.DependencyInjectionExtensions" Version="11.10.0" />
+    <PackageVersion Include="Humanizer.Core" Version="2.14.1" />
     <PackageVersion Include="IdGen" Version="3.0.7" />
     <PackageVersion Include="JetBrains.Annotations" Version="2024.3.0" />
     <PackageVersion Include="Mapster" Version="7.4.0" />

application/account-management/Core/Database/AccountManagementDbContext.cs

@@ -1,49 +1,8 @@
 using Microsoft.EntityFrameworkCore;
-using PlatformPlatform.AccountManagement.Features.Authentication.Domain;
-using PlatformPlatform.AccountManagement.Features.Signups.Domain;
-using PlatformPlatform.AccountManagement.Features.Tenants.Domain;
-using PlatformPlatform.AccountManagement.Features.Users.Domain;
-using PlatformPlatform.SharedKernel.Domain;
 using PlatformPlatform.SharedKernel.EntityFramework;
 using PlatformPlatform.SharedKernel.ExecutionContext;
 
 namespace PlatformPlatform.AccountManagement.Database;
 
 public sealed class AccountManagementDbContext(DbContextOptions<AccountManagementDbContext> options, IExecutionContext executionContext)
-    : SharedKernelDbContext<AccountManagementDbContext>(options, executionContext)
-{
-    public DbSet<Login> Logins => Set<Login>();
-
-    public DbSet<Signup> Signups => Set<Signup>();
-
-    public DbSet<Tenant> Tenants => Set<Tenant>();
-
-    public DbSet<User> Users => Set<User>();
-
-    protected override void OnModelCreating(ModelBuilder modelBuilder)
-    {
-        base.OnModelCreating(modelBuilder);
-
-        // Login
-        modelBuilder.MapStronglyTypedId<Login, LoginId, string>(t => t.Id);
-        modelBuilder.MapStronglyTypedId<Login, TenantId, string>(u => u.TenantId);
-        modelBuilder.MapStronglyTypedUuid<Login, UserId>(u => u.UserId);
-
-        // Signup
-        modelBuilder.MapStronglyTypedUuid<Signup, SignupId>(a => a.Id);
-        modelBuilder.MapStronglyTypedNullableId<Signup, TenantId, string>(u => u.TenantId);
-
-        // Tenant
-        modelBuilder.MapStronglyTypedId<Tenant, TenantId, string>(t => t.Id);
-
-        // User
-        modelBuilder.MapStronglyTypedUuid<User, UserId>(u => u.Id);
-        modelBuilder.MapStronglyTypedId<User, TenantId, string>(u => u.TenantId);
-        modelBuilder.Entity<User>()
-            .OwnsOne(e => e.Avatar, b => b.ToJson())
-            .HasOne<Tenant>()
-            .WithMany()
-            .HasForeignKey(u => u.TenantId)
-            .HasPrincipalKey(t => t.Id);
-    }
-}
+    : SharedKernelDbContext<AccountManagementDbContext>(options, executionContext);

application/account-management/Core/Features/Authentication/Domain/LoginConfiguration.cs

@@ -0,0 +1,16 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using PlatformPlatform.SharedKernel.Domain;
+using PlatformPlatform.SharedKernel.EntityFramework;
+
+namespace PlatformPlatform.AccountManagement.Features.Authentication.Domain;
+
+public sealed class LoginConfiguration : IEntityTypeConfiguration<Login>
+{
+    public void Configure(EntityTypeBuilder<Login> builder)
+    {
+        builder.MapStronglyTypedId<Login, LoginId, string>(t => t.Id);
+        builder.MapStronglyTypedId<Login, TenantId, string>(u => u.TenantId);
+        builder.MapStronglyTypedUuid<Login, UserId>(u => u.UserId);
+    }
+}

application/account-management/Core/Features/Signups/Domain/SignupConfiguration.cs

@@ -0,0 +1,15 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using PlatformPlatform.SharedKernel.Domain;
+using PlatformPlatform.SharedKernel.EntityFramework;
+
+namespace PlatformPlatform.AccountManagement.Features.Signups.Domain;
+
+public sealed class SignupConfiguration : IEntityTypeConfiguration<Signup>
+{
+    public void Configure(EntityTypeBuilder<Signup> builder)
+    {
+        builder.MapStronglyTypedUuid<Signup, SignupId>(a => a.Id);
+        builder.MapStronglyTypedNullableId<Signup, TenantId, string>(u => u.TenantId);
+    }
+}

application/account-management/Core/Features/Signups/Domain/SignupRepository.cs

@@ -14,7 +14,7 @@ public sealed class SignupRepository(AccountManagementDbContext accountManagemen
 {
     public Signup[] GetByEmailOrTenantId(TenantId tenantId, string email)
     {
-        return accountManagementDbContext.Signups
+        return DbSet
             .Where(r => !r.Completed)
             .Where(r => r.TenantId == tenantId || r.Email == email.ToLowerInvariant())
             .ToArray();

application/account-management/Core/Features/Tenants/Domain/TenantConfiguration.cs

@@ -0,0 +1,14 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using PlatformPlatform.SharedKernel.Domain;
+using PlatformPlatform.SharedKernel.EntityFramework;
+
+namespace PlatformPlatform.AccountManagement.Features.Tenants.Domain;
+
+public sealed class TenantConfiguration : IEntityTypeConfiguration<Tenant>
+{
+    public void Configure(EntityTypeBuilder<Tenant> builder)
+    {
+        builder.MapStronglyTypedId<Tenant, TenantId, string>(t => t.Id);
+    }
+}

application/account-management/Core/Features/Users/Domain/UserConfiguration.cs

@@ -0,0 +1,22 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using PlatformPlatform.AccountManagement.Features.Tenants.Domain;
+using PlatformPlatform.SharedKernel.Domain;
+using PlatformPlatform.SharedKernel.EntityFramework;
+
+namespace PlatformPlatform.AccountManagement.Features.Users.Domain;
+
+public sealed class UserConfiguration : IEntityTypeConfiguration<User>
+{
+    public void Configure(EntityTypeBuilder<User> builder)
+    {
+        builder.MapStronglyTypedUuid<User, UserId>(u => u.Id);
+        builder.MapStronglyTypedId<User, TenantId, string>(u => u.TenantId);
+        builder
+            .OwnsOne(e => e.Avatar, b => b.ToJson())
+            .HasOne<Tenant>()
+            .WithMany()
+            .HasForeignKey(u => u.TenantId)
+            .HasPrincipalKey(t => t.Id);
+    }
+}

application/account-management/Tests/DatabaseSeeder.cs

@@ -13,9 +13,9 @@ public sealed class DatabaseSeeder
     public DatabaseSeeder(AccountManagementDbContext accountManagementDbContext)
     {
         Tenant1 = Tenant.Create(new TenantId("tenant-1"), "[email protected]");
-        accountManagementDbContext.Tenants.AddRange(Tenant1);
+        accountManagementDbContext.Set<Tenant>().AddRange(Tenant1);
         User1 = User.Create(Tenant1.Id, "[email protected]", UserRole.Owner, true, null);
-        accountManagementDbContext.Users.AddRange(User1);
+        accountManagementDbContext.Set<User>().AddRange(User1);
 
         accountManagementDbContext.SaveChanges();
     }

application/shared-kernel/SharedKernel/EntityFramework/ModelBuilderExtensions.cs

@@ -1,5 +1,6 @@
 using System.Linq.Expressions;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
 using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
 using PlatformPlatform.SharedKernel.StronglyTypedIds;
 
@@ -11,37 +12,34 @@ public static class ModelBuilderExtensions
     ///     This method is used to tell Entity Framework how to map a strongly typed ID to a SQL column using the
     ///     underlying type of the strongly-typed ID.
     /// </summary>
-    public static void MapStronglyTypedLongId<T, TId>(this ModelBuilder modelBuilder, Expression<Func<T, TId>> expression)
+    public static void MapStronglyTypedLongId<T, TId>(this EntityTypeBuilder<T> builder, Expression<Func<T, TId>> expression)
         where T : class where TId : StronglyTypedLongId<TId>
     {
-        modelBuilder
-            .Entity<T>()
+        builder
             .Property(expression)
             .HasConversion(v => v.Value, v => (Activator.CreateInstance(typeof(TId), v) as TId)!);
     }
 
-    public static void MapStronglyTypedUuid<T, TId>(this ModelBuilder modelBuilder, Expression<Func<T, TId>> expression)
+    public static void MapStronglyTypedUuid<T, TId>(this EntityTypeBuilder<T> builder, Expression<Func<T, TId>> expression)
         where T : class where TId : StronglyTypedUlid<TId>
     {
-        modelBuilder
-            .Entity<T>()
+        builder
             .Property(expression)
             .HasConversion(v => v.Value, v => (Activator.CreateInstance(typeof(TId), v) as TId)!);
     }
 
-    public static void MapStronglyTypedId<T, TId, TValue>(this ModelBuilder modelBuilder, Expression<Func<T, TId>> expression)
+    public static void MapStronglyTypedId<T, TId, TValue>(this EntityTypeBuilder<T> builder, Expression<Func<T, TId>> expression)
         where T : class
         where TValue : IComparable<TValue>
         where TId : StronglyTypedId<TValue, TId>
     {
-        modelBuilder
-            .Entity<T>()
+        builder
             .Property(expression)
             .HasConversion(v => v.Value, v => (Activator.CreateInstance(typeof(TId), v) as TId)!);
     }
 
     public static void MapStronglyTypedNullableId<T, TId, TValue>(
-        this ModelBuilder modelBuilder,
+        this EntityTypeBuilder<T> builder,
         Expression<Func<T, TId?>> idExpression
     )
         where T : class
@@ -54,8 +52,7 @@ public static void MapStronglyTypedNullableId<T, TId, TValue>(
         var idCoalesceExpression =
             Expression.Lambda<Func<TId, TValue>>(Expression.Coalesce(idValueProperty, nullConstant), idParameter);
 
-        modelBuilder
-            .Entity<T>()
+        builder
             .Property(idExpression)
             .HasConversion(idCoalesceExpression!, v => Activator.CreateInstance(typeof(TId), v) as TId);
     }

application/shared-kernel/SharedKernel/EntityFramework/SharedKernelDbContext.cs

@@ -1,4 +1,5 @@
 using System.Linq.Expressions;
+using Humanizer;
 using Microsoft.EntityFrameworkCore;
 using PlatformPlatform.SharedKernel.Domain;
 using PlatformPlatform.SharedKernel.ExecutionContext;
@@ -24,6 +25,15 @@ protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
 
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
+        modelBuilder.ApplyConfigurationsFromAssembly(typeof(TContext).Assembly);
+
+        // Set pluralized table names for all aggregates
+        foreach (var entityType in modelBuilder.Model.GetEntityTypes())
+        {
+            var tableName = entityType.GetTableName()!.Pluralize();
+            entityType.SetTableName(tableName);
+        }
+
         // Ensures that all enum properties are stored as strings in the database.
         modelBuilder.UseStringForEnums();
 

application/shared-kernel/SharedKernel/SharedKernel.csproj

@@ -23,6 +23,7 @@
         <PackageReference Include="Azure.Security.KeyVault.Keys" />
         <PackageReference Include="Azure.Security.KeyVault.Secrets" />
         <PackageReference Include="FluentValidation.DependencyInjectionExtensions" />
+        <PackageReference Include="Humanizer.Core" />
         <PackageReference Include="IdGen" />
         <PackageReference Include="JetBrains.Annotations" />
         <PackageReference Include="Mapster" />