Сделал часть моделей хранилища

Bank/BankContracts/BindingModels/RequestBindingModel.cs

@@ -13,5 +13,6 @@ namespace BankContracts.BindingModels
 		public int Sum { get; set; }
 		public DateTime RequestTime { get; set; }
 		public RequestStatus Status { get; set; }
+		public Dictionary<int, ICardModel> CardRequests { get; set; } = new();
 	}
 }

Bank/BankContracts/ViewModels/RequestViewModel.cs

@@ -18,5 +18,7 @@ namespace BankContracts.ViewModels
 		public DateTime RequestTime { get; set; }
 		[DisplayName("Статус заявки")]
 		public RequestStatus Status { get; set; }
+		public Dictionary<int, ICardModel> CardRequests { get; set; } = new();
+
 	}
 }

Bank/BankDataModels/Models/IRequestModel.cs

@@ -11,5 +11,7 @@ namespace BankDataModels.Models
         int Sum { get; set; }
         DateTime RequestTime { get; set; }
         RequestStatus Status { get; set; }
-    }
+		Dictionary<int, ICardModel> CardRequests { get; }
+
+	}
 }

Bank/BankDatabaseImplement/BankDatabase.cs

@@ -1,4 +1,5 @@
-using Microsoft.EntityFrameworkCore;
+using BankDatabaseImplement.Models;
+using Microsoft.EntityFrameworkCore;
 
 namespace BankDatabaseImplement
 {
@@ -13,5 +14,11 @@ namespace BankDatabaseImplement
 			}
 			base.OnConfiguring(optionsBuilder);
 		}
+
+		public virtual DbSet<Client> Clients { get; set; }
+		public virtual DbSet<Card> Cards { get; set; }
+		public virtual DbSet<Operation> Operations { get; set; }
+		public virtual DbSet<Request> Requests { get; set; }
+		public virtual DbSet<CardRequest> CardRequests { get; set; }
 	}
 }

Bank/BankDatabaseImplement/Models/CardRequest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -8,5 +9,12 @@ namespace BankDatabaseImplement.Models
 {
 	public class CardRequest
 	{
+		public int Id { get; set; }
+		[Required]
+		public int CardId { get; set; }
+		[Required]
+		public int RequestId {  get; set; }
+		public virtual Card Card { get; set; } = new();
+		public virtual Request Request { get; set; } = new();
 	}
 }

Bank/BankDatabaseImplement/Models/Operation.cs

@@ -1,6 +1,7 @@
 using Azure;
 using BankContracts.BindingModels;
 using BankContracts.ViewModels;
+using BankDataModels.Models;
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
@@ -10,7 +11,7 @@ using System.Threading.Tasks;
 
 namespace BankDatabaseImplement.Models
 {
-	public class Operation
+	public class Operation : IOperationModel
 	{
 		public int Id { get; set; }
 		[Required]

Bank/BankDatabaseImplement/Models/Request.cs

@@ -0,0 +1,90 @@
+using BankContracts.BindingModels;
+using BankDataModels.Models;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace BankDatabaseImplement.Models
+{
+	public class Request : IRequestModel
+	{
+		public int Id { get; set; }
+		[Required]
+		public int Sum { get; set; }
+		[Required]
+		public DateTime RequestTime { get; set; }
+		[Required]
+		public RequestStatus Status { get; set; }
+		[ForeignKey("RequestId")]
+		public virtual List<CardRequest> Cards { get; set; } = new();
+		private Dictionary<int, ICardModel>? _cardRequests { get; set; } = null;
+		[NotMapped]
+		public Dictionary<int, ICardModel> CardRequests
+		{
+			get
+			{
+				if (_cardRequests == null)
+				{
+					_cardRequests = Cards.ToDictionary(recPC => recPC.CardId, recPC => recPC.Card as ICardModel);
+				}
+				return _cardRequests;
+			}
+		}
+
+		public static Request Create(BankDatabase context, RequestBindingModel model)
+		{
+			return new Request
+			{
+				Id = model.Id,
+				Sum = model.Sum,
+				RequestTime = model.RequestTime,
+				Status = model.Status,
+				Cards = model.CardRequests.Select(x => new CardRequest
+				{
+					Card = context.Cards.First(y => y.Id == x.Key)
+				}).ToList()
+			};
+		}
+
+		public void Update(RequestBindingModel model)
+		{
+			Sum = model.Sum;
+			RequestTime = model.RequestTime;
+			Status = model.Status;
+		}
+
+		public RequestBindingModel GetViewModel => new()
+		{
+			Id = Id,
+			Sum = Sum,
+			RequestTime = RequestTime,
+			Status = Status,
+			CardRequests = CardRequests
+		};
+
+		public void UpdateCards(BankDatabase context, RequestBindingModel model)
+		{
+			var CardRequests = context.CardRequests.Where(rec => rec.RequestId == model.Id).ToList();
+			if (CardRequests != null && CardRequests.Count > 0)
+			{ // удалили те, которых нет в модели
+				context.CardRequests.RemoveRange(CardRequests.Where(rec => !model.CardRequests.ContainsKey(rec.CardId)));
+				context.SaveChanges();
+			}
+			var Request = context.Requests.First(x => x.Id == Id);
+			foreach (var request in model.CardRequests)
+			{
+				context.CardRequests.Add(new CardRequest
+				{
+					Request = Request,
+					Card = context.Cards.First(x => x.Id == request.Key),
+				});
+				context.SaveChanges();
+			}
+			_cardRequests = null;
+		}
+	}
+}