CourseWork_SchoolStudyAgain/SchoolAgainStudy/SchoolAgainStudyDataBaseImplements/Implements/StudentStorage.cs

using Microsoft.EntityFrameworkCore;
using SchoolAgainStudyContracts.BindingModel;
using SchoolAgainStudyContracts.SearchModel;
using SchoolAgainStudyContracts.StorageContracts;
using SchoolAgainStudyContracts.ViewModel;
using SchoolAgainStudyDataBaseImplements.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.ConstrainedExecution;
using System.Text;
using System.Threading.Tasks;

namespace SchoolAgainStudyDataBaseImplements.Implements
{
    public class StudentStorage : IStudentStorage
    {
        public StudentViewModel? Delete(StudentBindingModel model)
        {
            using var context = new SchoolDataBase();
            var element = context.Students 
                .FirstOrDefault(rec => rec.Id == model.Id);
            if (element != null)
            {
                context.Students.Remove(element);
                context.SaveChanges();
                return element.GetViewModel;
            }
            return null;
        }

        public StudentViewModel? GetElement(StudentSearchModel model)
        {
            if (string.IsNullOrEmpty(model.Login) && !model.Id.HasValue)
            {
                return null;
            }
            using var context = new SchoolDataBase();
            return context.Students
                .FirstOrDefault(x => (!string.IsNullOrEmpty(model.Login) && x.Login == model.Login) ||
                                (model.Id.HasValue && x.Id == model.Id))
                ?.GetViewModel;
        }

        public List<StudentViewModel> GetFilteredList(StudentSearchModel model)
        {
            if (string.IsNullOrEmpty(model.Name))
            {
                return new();
            }
            using var context = new SchoolDataBase();
            return context.Students
                    .Where(x => x.Name.Contains(model.Name))
                    .ToList()
                    .Select(x => x.GetViewModel)
                    .ToList();
        }

        public List<StudentViewModel> GetFullList()
        {
            using var context = new SchoolDataBase();
            return context.Students
                    .ToList()
                    .Select(x => x.GetViewModel)
                    .ToList();
        }

        public StudentViewModel? Insert(StudentBindingModel model)
        {
            using var context = new SchoolDataBase();
            var newStudent = Student.Create(context, model);
            if (newStudent == null)
            {
                return null;
            }
            context.Students.Add(newStudent);
            context.SaveChanges();
            return newStudent.GetViewModel;
        }

        public StudentViewModel? Update(StudentBindingModel model)
        {
            using var context = new SchoolDataBase();
            using var transaction = context.Database.BeginTransaction();
            try
            {
                var student = context.Students.FirstOrDefault(rec => rec.Id == model.Id);
                if (student == null)
                {
                    return null;
                }
                student.Update(model);
                context.SaveChanges();
                transaction.Commit();
                return student.GetViewModel;
            }
            catch
            {
                transaction.Rollback();
                throw;
            }
        }
    }
}