CrudRepository.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using BooksWebApi.Data;
using BooksWebApi.Entities;
using Microsoft.EntityFrameworkCore;

public class CrudRepository : ICrudRepository
{
  private readonly BooksCatalogDbContext _context;
  public CrudRepository(BooksCatalogDbContext context)
  {
    _context = context;
  }

  public void Add<T>(T entity) where T : class
  {
    _context.Add(entity);
  }

  public void Delete<T>(T entity) where T : class
  {
    _context.Remove(entity);
  }

  public Book GetBook(int id)
  {
    return _context.Books
           .Include(b => b.Category)
           .Where(b => b.Id == id)             
           .FirstOrDefault();
  }

  public IEnumerable<Book> GetBooks()
  {
     return _context.Books
            .Include(b => b.Category)
            .ToList();
  } 

  public IEnumerable<Book> GetBooksByCategory(string category)
  {
    return _context.Books
           .Where(c => c.Category.Description.Equals(category, StringComparison.CurrentCultureIgnoreCase))
           .Include(c => c.Category)
           .OrderBy(b => b.Name)
           .ToList();
  }

  public Category GetCategoryWithBooks(int id)
  {
    return _context.Categories
           .Where(c => c.Id == id)
           .Include(c => c.Books)								
           .FirstOrDefault();
  }

  public User GetUser(string userName)
  {
     return _context.Users								 
            .Where(u => u.UserName == userName)
            .Cast<User>()
            .FirstOrDefault();
  }

  public async Task<bool> SaveAllAsync()
  {
    return (await _context.SaveChangesAsync() > 0);
  }
 }
}