Fix (?) issues related with concurrency

Core/Data/CoreContext.cs

@@ -1,29 +1,20 @@
-using System.Threading.Tasks;
+using Kruzya.TelegramBot.Core.EF;
 using Microsoft.EntityFrameworkCore;
 
 namespace Kruzya.TelegramBot.Core.Data
 {
-    public class CoreContext : DbContext
+    public class CoreContext : AutoSaveDbContext
     {
         /// <summary>
         /// The all known users.
         /// </summary>
         public DbSet<BotUser> Users { get; set; }
 
+        /// <summary>
+        /// The all knows user options and values.
+        /// </summary>
         public DbSet<BotUserValue> UserValues { get; set; }
 
-        public override void Dispose()
-        {
-            SaveChanges();
-            base.Dispose();
-        }
-        
-        public override ValueTask DisposeAsync()
-        {
-            SaveChanges(); 
-            return base.DisposeAsync();
-        }
-
         public CoreContext(DbContextOptions<CoreContext> ctx) : base(ctx)
         {
             Database.Migrate();

Core/EF/AutoSaveDbContext.Add.cs

@@ -0,0 +1,22 @@
+using Microsoft.EntityFrameworkCore.ChangeTracking;
+
+namespace Kruzya.TelegramBot.Core.EF;
+
+public abstract partial class AutoSaveDbContext
+{
+    public override EntityEntry Add(object entity)
+    {
+        var entry = base.Add(entity);
+        SaveChanges();
+
+        return entry;
+    }
+
+    public override EntityEntry<TEntity> Add<TEntity>(TEntity entity)
+    {
+        var entry = base.Add(entity);
+        SaveChanges();
+
+        return entry;
+    }
+}

Core/EF/AutoSaveDbContext.Remove.cs

@@ -0,0 +1,22 @@
+using Microsoft.EntityFrameworkCore.ChangeTracking;
+
+namespace Kruzya.TelegramBot.Core.EF;
+
+public abstract partial class AutoSaveDbContext
+{
+    public override EntityEntry Remove(object entity)
+    {
+        var entry = base.Remove(entity);
+        SaveChanges();
+
+        return entry;
+    }
+
+    public override EntityEntry<TEntity> Remove<TEntity>(TEntity entity)
+    {
+        var entry = base.Remove(entity);
+        SaveChanges();
+
+        return entry;
+    }
+}

Core/EF/AutoSaveDbContext.Update.cs

@@ -0,0 +1,22 @@
+using Microsoft.EntityFrameworkCore.ChangeTracking;
+
+namespace Kruzya.TelegramBot.Core.EF;
+
+public abstract partial class AutoSaveDbContext
+{
+    public override EntityEntry Update(object entity)
+    {
+        var entry = base.Update(entity);
+        SaveChanges();
+
+        return entry;
+    }
+
+    public override EntityEntry<TEntity> Update<TEntity>(TEntity entity)
+    {
+        var entry = base.Update(entity);
+        SaveChanges();
+
+        return entry;
+    }
+}

Core/EF/AutoSaveDbContext.cs

@@ -0,0 +1,12 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace Kruzya.TelegramBot.Core.EF;
+
+/// <summary>
+/// EF database context with autosaving feature.
+/// </summary>
+public abstract partial class AutoSaveDbContext : DbContext
+{
+    protected AutoSaveDbContext(DbContextOptions options) : base(options)
+    {}
+}

modules/RichSiteSummary/Data/RichSiteSummaryContext.cs

@@ -1,8 +1,9 @@
-using Microsoft.EntityFrameworkCore;
+using Kruzya.TelegramBot.Core.EF;
+using Microsoft.EntityFrameworkCore;
 
 namespace Kruzya.TelegramBot.RichSiteSummary.Data
 {
-    public class RichSiteSummaryContext : DbContext
+    public class RichSiteSummaryContext : AutoSaveDbContext
     {
         /// <summary>
         /// Repository with all feeds in database.