переделала интерфейсы под классы-модели, запихнула в папку и пока только создала абстрактный класс для работы с хранилищем (с бд)

BeautySalon/BeautySalonDBModels/AbstractWorkWithStorage.cs

@@ -6,9 +6,8 @@ using System.Threading.Tasks;
 
 namespace BeautySalonDBModels
 {
-    public interface ISpecialisation 
+    public abstract class AbstractWorkWithStorage
     {
-        int SpecialisationId { get; }
-        string Name { get; }
+        public abstract void AddClient(Clien);
     }
 }

BeautySalon/BeautySalonDBModels/BeautySalonDBModels.csproj

@@ -8,6 +8,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Logging" Version="8.0.0" />
+	  <PackageReference Include="Npgsql" Version="8.0.2" />
   </ItemGroup>
 
 </Project>

BeautySalon/BeautySalonDBModels/ICheque.cs

@@ -1,15 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace BeautySalonDBModels
-{
-    public interface ICheque
-    {
-        int ChequeId { get; }
-        int ClientId { get; }
-        string ReceptionId { get; }
-    }
-}

BeautySalon/BeautySalonDBModels/IClient.cs

@@ -1,15 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace BeautySalonDBModels
-{
-    public interface IClient 
-    {
-        int ClientId { get; }
-        string FIO {  get; }
-        int Age { get; }
-    }
-}

BeautySalon/BeautySalonDBModels/IMaster.cs

@@ -1,15 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace BeautySalonDBModels
-{
-    public interface IMaster 
-    {
-        int MasterId { get; }
-        int SpecialisationId { get; }
-        string FIO {  get; }
-    }
-}

BeautySalon/BeautySalonDBModels/IReception.cs

@@ -1,16 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace BeautySalonDBModels
-{
-    public interface IReception 
-    {
-        int ReceptionId { get; }
-        int MasterId { get; }
-        int ServiceId { get; }
-        DateTime DateReception { get; }
-    }
-}

BeautySalon/BeautySalonDBModels/IService.cs

@@ -1,16 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace BeautySalonDBModels
-{
-    public interface IService 
-    {
-        int ServiceId { get; }
-        string ServiceName { get; }
-        double Price { get; }
-        int SpecialisationId { get; }
-    }
-}

BeautySalon/BeautySalonDBModels/Models/Cheque.cs

@@ -0,0 +1,9 @@
+namespace BeautySalonDBModels.Models
+{
+    public class Cheque
+    {
+        public int ChequeId { get; }
+        public int ClientId { get; }
+        public int ReceptionId { get; }
+    }
+}

BeautySalon/BeautySalonDBModels/Models/Client.cs

@@ -0,0 +1,9 @@
+namespace BeautySalonDBModels.Models
+{
+    public class Client
+    {
+        public int ClientId { get; }
+        public string FIO { get; } = string.Empty;
+        public int Age { get; }
+    }
+}

BeautySalon/BeautySalonDBModels/Models/Master.cs

@@ -0,0 +1,9 @@
+namespace BeautySalonDBModels.Models
+{
+    public class Master
+    {
+        public int MasterId { get; }
+        public int SpecialisationId { get; }
+        public string FIO { get; } = string.Empty;
+    }
+}

BeautySalon/BeautySalonDBModels/Models/Reception.cs

@@ -0,0 +1,10 @@
+namespace BeautySalonDBModels.Models
+{
+    public class Reception
+    {
+        public int ReceptionId { get; }
+        public int MasterId { get; }
+        public int ServiceId { get; }
+        public DateTime DateReception { get; }
+    }
+}

BeautySalon/BeautySalonDBModels/Models/Service.cs

@@ -0,0 +1,10 @@
+namespace BeautySalonDBModels.Models
+{
+    public class Service
+    {
+        public int ServiceId { get; }
+        public string ServiceName { get; } = string.Empty;
+        public double Price { get; }
+        public int SpecialisationId { get; }
+    }
+}

BeautySalon/BeautySalonDBModels/Models/Specialisation.cs

@@ -0,0 +1,8 @@
+namespace BeautySalonDBModels.Models
+{
+    public class Specialisation
+    {
+        public int SpecialisationId { get; }
+        public string Name { get; } = string.Empty; 
+    }
+}