Add Exception middleware

Data/UnitOfWork.cs

@@ -1,17 +1,23 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace Diary.Data
+namespace Diary.Data
 {
-	public class UnitOfWork
-	{
-		public UnitOfWork()
-		{
 
+	public interface IUnitOfWork
+	{
+		Task CompleteAsync();
+	}
+
+	public class UnitOfWork:IUnitOfWork
+	{
+		private readonly IDiaryDBContext _context;
+
+		public UnitOfWork(IDiaryDBContext context)
+		{
+			_context = context ?? throw new ArgumentNullException(nameof(context));
 		}
 
+		public async Task CompleteAsync()
+		{
+			await _context.SaveChangesAsync();
+		}
 	}
-}
+}