Добавил интерфейсы и сделал для них заглушки

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Entities/Doctor.cs

@@ -22,8 +22,8 @@ public class Doctor
         return new Doctor
         {
             Id = id,
-            First_Name = first_Name,
+            First_Name = first_Name ?? string.Empty,
-            Last_Name = last_Name,
+            Last_Name = last_Name ?? string.Empty,
             DoctorPost = doctorPost
         };
     }

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Entities/Patient.cs

@@ -14,12 +14,12 @@ public class Patient
 
     public string Last_Name {  get; private set; } = string.Empty;
 
-    public int ContactNumber { get; private set; }
+    public string ContactNumber { get; private set; }
 
 
     // ТУТ СДЕЛАЕМ СТАТИСТИЧЕСКИЙ МЕТОД
 
-    public static Patient CreatePatient(int id, string firts_Name, string last_Name, int contactNumber)
+    public static Patient CreatePatient(int id, string firts_Name, string last_Name, string contactNumber)
     {
         return new Patient
         {

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Repositories/IDoctorPaymentsRepository.cs

@@ -0,0 +1,21 @@
+using RegistrationPatientsPolyclinic.Entities;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RegistrationPatientsPolyclinic.Repositories;
+
+public interface IDoctorPaymentsRepository
+{
+    IEnumerable<IDoctorPaymentsRepository> ReadDoctorPayments();
+
+    DoctorPayments ReadDoctorPaymentsById(int id);
+
+    void CreateDoctorPayments(DoctorPayments doctorPayments);
+
+    void UpdateDoctorPayments(DoctorPayments doctorPayments);
+
+    void DeleteDoctorPayments(int id);
+}

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Repositories/IDoctorRepository.cs

@@ -0,0 +1,21 @@
+using RegistrationPatientsPolyclinic.Entities;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RegistrationPatientsPolyclinic.Repositories;
+
+public interface IDoctorRepository
+{
+    IEnumerable<Doctor> ReadDoctors();
+
+    Doctor ReadDoctorById(int id);
+
+    void CreateDoctor(Doctor doctor);
+
+    void UpdateDoctor(Doctor doctor);
+
+    void DeleteDoctor(int id);
+}

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Repositories/IMedicalHistoryRepository.cs

@@ -0,0 +1,16 @@
+using RegistrationPatientsPolyclinic.Entities;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RegistrationPatientsPolyclinic.Repositories;
+
+public interface IMedicalHistoryRepository
+{
+    IEnumerable<MedicalHistory> ReadMedicalHistory(DateTime? dateForm = null, DateTime? dateTo = null, int? PatientId = null,
+        int? DoctorId = null);  // по этим параметрам можно не весь список читать, а только какую то часть
+
+    void CreateMedicalHistory(MedicalHistory medicalHistory);  // объекь будет заносится в список
+}

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Repositories/IPatientRepository.cs

@@ -0,0 +1,24 @@
+using RegistrationPatientsPolyclinic.Entities;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RegistrationPatientsPolyclinic.Repositories;
+
+/// <summary>
+/// Операцию read (чтение) разобьем на 2 метода: получение коллекции и получений одной записи по идентификатору.
+/// </summary>
+public interface IPatientRepository
+{
+    IEnumerable<Patient> ReadPatient(); // метод получения всего списка (в данном случае пациентов)
+
+    Patient ReadPatientById(int id); // получение по id
+
+    void CreatPatient(Patient patient); // метод для того чтобы добавить в существующую коллекцию пациента
+ 
+    void UpdatePatient(Patient patient); // метод на изменение
+
+    void DeletePatient(int id);
+}

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Repositories/Implementations/DoctorPaymentsRepository.cs

@@ -0,0 +1,33 @@
+using RegistrationPatientsPolyclinic.Entities;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RegistrationPatientsPolyclinic.Repositories.Implementations;
+
+public class DoctorPaymentsRepository : IDoctorPaymentsRepository
+{
+    public void CreateDoctorPayments(DoctorPayments doctorPayments)
+    {
+    }
+
+    public void DeleteDoctorPayments(int id)
+    {
+    }
+
+    public IEnumerable<IDoctorPaymentsRepository> ReadDoctorPayments()
+    {
+        return [];
+    }
+
+    public DoctorPayments ReadDoctorPaymentsById(int id)
+    {
+        return DoctorPayments.CreateElement(0, 0, string.Empty, 0, 0);
+    }
+
+    public void UpdateDoctorPayments(DoctorPayments doctorPayments)
+    {
+    }
+}

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Repositories/Implementations/DoctorRepository.cs

@@ -0,0 +1,34 @@
+using RegistrationPatientsPolyclinic.Entities;
+using RegistrationPatientsPolyclinic.Entities.Enums;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RegistrationPatientsPolyclinic.Repositories.Implementations;
+
+public class DoctorRepository : IDoctorRepository
+{
+    public void CreateDoctor(Doctor doctor)
+    {
+    }
+
+    public void DeleteDoctor(int id)
+    {
+    }
+
+    public Doctor ReadDoctorById(int id)
+    {
+        return Doctor.CreateEntity(0, string.Empty, string.Empty, DoctorPost.None);
+    }
+
+    public IEnumerable<Doctor> ReadDoctors()
+    {
+        return [];
+    }
+
+    public void UpdateDoctor(Doctor doctor)
+    {
+    }
+}

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Repositories/Implementations/MedicalHistoryRepository.cs

@@ -0,0 +1,20 @@
+using RegistrationPatientsPolyclinic.Entities;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RegistrationPatientsPolyclinic.Repositories.Implementations;
+
+public class MedicalHistoryRepository : IMedicalHistoryRepository
+{
+    public void CreateMedicalHistory(MedicalHistory medicalHistory)
+    {
+    }
+
+    public IEnumerable<MedicalHistory> ReadMedicalHistory(DateTime? dateForm = null, DateTime? dateTo = null, int? PatientId = null, int? DoctorId = null)
+    {
+        return [];
+    }
+}

RegistrationPatientsPolyclinic/RegistrationPatientsPolyclinic/Repositories/Implementations/PatientRepository.cs

@@ -0,0 +1,33 @@
+using RegistrationPatientsPolyclinic.Entities;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RegistrationPatientsPolyclinic.Repositories.Implementations;
+
+public class PatientRepository : IPatientRepository
+{
+    public void CreatPatient(Patient patient)
+    {
+    }
+
+    public void DeletePatient(int id)
+    {
+    }
+
+    public IEnumerable<Patient> ReadPatient()
+    {
+        return [];
+    }
+
+    public Patient ReadPatientById(int id)
+    {
+        return Patient.CreatePatient(0, string.Empty, string.Empty, string.Empty);
+    }
+
+    public void UpdatePatient(Patient patient)
+    {
+    }
+}