Cascade delete mini game ranking entries

A character which has participated in a mini game with enabled ranking
statistics could not be deleted. The database rejected it with

  Npgsql.PostgresException 23503: update or delete on table "Character"
  violates foreign key constraint "FK_MiniGameRankingEntry_Character_CharacterId"

MiniGameRankingEntry is a member of neither the character nor the mini game
definition aggregate, so the model generator doesn't emit a delete behavior
for its references. The entity was registered without any additional
configuration, so Entity Framework fell back to no action for these optional
relationships, which the database translates into a restricting foreign key.

Both references are now configured with a cascading delete, matching the
behavior of the other references to a character. With that, all seven
relationships pointing to Character delete their dependents.

This affects both deletion paths: the one of the player
(DeleteCharacterAction) and the one of an administrator, who can remove a
character from the account in the admin panel.

The cascade on the mini game definition is deliberate and part of the same
defect: deleting a definition in the admin panel ran into the very same
restriction. It does mean that the ranking history of a mini game is dropped
together with its definition.

Reported in issue 796.

(cherry picked from commit a391bdedbbd3a36ccb37124125bd7ede4f851dca)

src/Persistence/EntityFramework/EntityDataContext.cs

@@ -44,7 +44,7 @@ public class EntityDataContext : ExtendedTypeContext
         modelBuilder.Entity<Model.AttributeDefinition>();
         modelBuilder.Entity<ConnectServerDefinition>();
         modelBuilder.Entity<ChatServerDefinition>();
-        modelBuilder.Entity<MiniGameRankingEntry>();
+        modelBuilder.Entity<MiniGameRankingEntry>().Apply();
         modelBuilder.Entity<GameServerDefinition>(entity =>
         {
             entity.Property(e => e.PvpEnabled).HasDefaultValue(true);

src/Persistence/EntityFramework/Extensions/ModelBuilder/MiniGameExtensions.cs

@@ -4,6 +4,7 @@
 
 namespace MUnique.OpenMU.Persistence.EntityFramework.Extensions.ModelBuilder;
 
+using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Metadata.Builders;
 using MUnique.OpenMU.Persistence.EntityFramework.Model;
 
@@ -41,4 +42,21 @@ internal static class MiniGameExtensions
         builder.Property(p => p.Name).HasConversion(LocalizedStringConverter.Instance);
         builder.Property(p => p.Description).HasConversion(LocalizedStringConverter.Instance);
     }
+
+    /// <summary>
+    /// Applies the settings for the <see cref="MiniGameRankingEntry"/> entity.
+    /// </summary>
+    /// <param name="builder">The builder.</param>
+    /// <remarks>
+    /// A ranking entry is a member of neither the character's nor the mini game definition's
+    /// aggregate. The model generator only emits a cascading delete for navigations marked with
+    /// <see cref="MUnique.OpenMU.DataModel.Composition.MemberOfAggregateAttribute"/>, so these two
+    /// references are left without a delete behavior; Entity Framework then defaults to no action
+    /// for them, and the database refuses to delete a character which has played a mini game.
+    /// </remarks>
+    public static void Apply(this EntityTypeBuilder<MiniGameRankingEntry> builder)
+    {
+        builder.HasOne(entry => entry.RawCharacter).WithMany().OnDelete(DeleteBehavior.Cascade);
+        builder.HasOne(entry => entry.RawMiniGame).WithMany().OnDelete(DeleteBehavior.Cascade);
+    }
 }

src/Persistence/EntityFramework/Migrations/20260723073950_CascadeDeleteMiniGameRankingEntries.cs

@@ -0,0 +1,80 @@
+// <copyright file="20260723073950_CascadeDeleteMiniGameRankingEntries.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+#nullable disable
+
+namespace MUnique.OpenMU.Persistence.EntityFramework.Migrations
+{
+    using Microsoft.EntityFrameworkCore.Migrations;
+
+    /// <inheritdoc />
+    public partial class CascadeDeleteMiniGameRankingEntries : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_MiniGameRankingEntry_Character_CharacterId",
+                schema: "data",
+                table: "MiniGameRankingEntry");
+
+            migrationBuilder.DropForeignKey(
+                name: "FK_MiniGameRankingEntry_MiniGameDefinition_MiniGameId",
+                schema: "data",
+                table: "MiniGameRankingEntry");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_MiniGameRankingEntry_Character_CharacterId",
+                schema: "data",
+                table: "MiniGameRankingEntry",
+                column: "CharacterId",
+                principalSchema: "data",
+                principalTable: "Character",
+                principalColumn: "Id",
+                onDelete: ReferentialAction.Cascade);
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_MiniGameRankingEntry_MiniGameDefinition_MiniGameId",
+                schema: "data",
+                table: "MiniGameRankingEntry",
+                column: "MiniGameId",
+                principalSchema: "config",
+                principalTable: "MiniGameDefinition",
+                principalColumn: "Id",
+                onDelete: ReferentialAction.Cascade);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_MiniGameRankingEntry_Character_CharacterId",
+                schema: "data",
+                table: "MiniGameRankingEntry");
+
+            migrationBuilder.DropForeignKey(
+                name: "FK_MiniGameRankingEntry_MiniGameDefinition_MiniGameId",
+                schema: "data",
+                table: "MiniGameRankingEntry");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_MiniGameRankingEntry_Character_CharacterId",
+                schema: "data",
+                table: "MiniGameRankingEntry",
+                column: "CharacterId",
+                principalSchema: "data",
+                principalTable: "Character",
+                principalColumn: "Id");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_MiniGameRankingEntry_MiniGameDefinition_MiniGameId",
+                schema: "data",
+                table: "MiniGameRankingEntry",
+                column: "MiniGameId",
+                principalSchema: "config",
+                principalTable: "MiniGameDefinition",
+                principalColumn: "Id");
+        }
+    }
+}

src/Persistence/EntityFramework/Migrations/EntityDataContextModelSnapshot.cs

@@ -4627,11 +4627,13 @@ namespace MUnique.OpenMU.Persistence.EntityFramework.Migrations
                 {
                     b.HasOne("MUnique.OpenMU.Persistence.EntityFramework.Model.Character", "RawCharacter")
                         .WithMany()
-                        .HasForeignKey("CharacterId");
+                        .HasForeignKey("CharacterId")
+                        .OnDelete(DeleteBehavior.Cascade);
 
                     b.HasOne("MUnique.OpenMU.Persistence.EntityFramework.Model.MiniGameDefinition", "RawMiniGame")
                         .WithMany()
-                        .HasForeignKey("MiniGameId");
+                        .HasForeignKey("MiniGameId")
+                        .OnDelete(DeleteBehavior.Cascade);
 
                     b.Navigation("RawCharacter");