CourseWork/University/UniversityDatabaseImplement/Implements/StatementStorage.cs

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using UniversityContracts.BindingModels;
using UniversityContracts.SearchModels;
using UniversityContracts.StorageContracts;
using UniversityContracts.ViewModels;
using UniversityDatabaseImplement.Models;

namespace UniversityDatabaseImplement.Implements
{
    public class StatementStorage: IStatementStorage
    {
        public StatementViewModel? GetElement(StatementSearchModel model)
        {
            if (!model.Id.HasValue)
            {
                return null;
            }
            using var context = new UniversityDatabase();
            return context.Statements.Include(x => x.Teacher).FirstOrDefault(x => (model.Id.HasValue && x.Id == model.Id))?.GetViewModel;
        }

        public List<StatementViewModel> GetFilteredList(StatementSearchModel model)
        {
            if (!model.Id.HasValue && !model.Date.HasValue)
            {
                return new();
            }
            using var context = new UniversityDatabase();
            return context.Statements
            .Where(x => x.Id == model.Id || model.Date <= x.Date)
            .Include(x => x.Teacher)
            .Select(x => x.GetViewModel)
            .ToList();
        }

        public List<StatementViewModel> GetFullList()
        {
            using var context = new UniversityDatabase();
            return context.Statements.Include(x => x.Teacher).Select(x => x.GetViewModel).ToList();
        }

        public StatementViewModel? Insert(StatementBindingModel model)
        {
            var newStatement = Statement.Create(model);
            if (newStatement == null)
            {
                return null;
            }
            using var context = new UniversityDatabase();
            context.Statements.Add(newStatement);
            context.SaveChanges();
            return context.Statements.Include(x => x.Teacher).FirstOrDefault(x => x.Id == newStatement.Id)?.GetViewModel;
        }

        public StatementViewModel? Update(StatementBindingModel model)
        {
            using var context = new UniversityDatabase();
            var order = context.Statements.FirstOrDefault(x => x.Id == model.Id);
            if (order == null)
            {
                return null;
            }
            order.Update(model);
            context.SaveChanges();
            return context.Statements.Include(x => x.Teacher).FirstOrDefault(x => x.Id == model.Id)?.GetViewModel;
        }
        public StatementViewModel? Delete(StatementBindingModel model)
        {
            using var context = new UniversityDatabase();
            var element = context.Statements.FirstOrDefault(rec => rec.Id == model.Id);
            if (element != null)
            {
                context.Statements.Remove(element);
                context.SaveChanges();
                return element.GetViewModel;
            }
            return null;
        }
    }
}