如何在 MVC 控制器中实现数据访问层

Question

我了解数据访问层或简称 DAL 用于访问和检索数据库中的信息，但我不确定如何在控制器中调用 DAL 数据。 例如，我在我的 DAL 中创建了这个静态类，但我不确定如何将它调用到我的控制器，任何帮助或指南将不胜感激。 DohvatiMetodu 是类的名称。

public static FormInputViewModel DohvatiMetodu()
        {
            var viewModel = new FormInputViewModel();
            var metoda = new List<Metoda>();
            var metodaList = new List<SelectListItem>();

            using (var db = new ApplicationDbContext())
            {
                metoda = db.Metoda.ToList();
            }

            foreach (var metod in metoda)
            {
                metodaList.Add(new SelectListItem() {Value = metod.Id.ToString(), Text = metod.Naziv});
            }

            viewModel.KoristenaMetoda = metodaList;


            return viewModel;

Answer 1

根据用户的许多要求，我使用简单的 CRUD 方法逐步更新了具有完整 存储库模式 的代码：

存储库模式在应用程序的数据层和域层之间添加了一个分离层。它还使应用程序的数据访问部分具有更好的可测试性。

数据库工厂 (IDatabaseFactory.cs)：

public interface IDatabaseFactory : IDisposable
{
    Database_DBEntities Get();
}

数据库工厂实现（DatabaseFactory.cs）：

public class DatabaseFactory : Disposable, IDatabaseFactory
{
    private Database_DBEntities dataContext;
    public Database_DBEntities Get()
    {
        return dataContext ?? (dataContext = new Database_DBEntities());
    }

    protected override void DisposeCore()
    {
        if (dataContext != null)
            dataContext.Dispose();
    }
}

基础接口 (IRepository.cs)：

public interface IRepository<T> where T : class
{
    void Add(T entity);
    void Update(T entity);
    void Detach(T entity);
    void Delete(T entity);
    T GetById(long Id);
    T GetById(string Id);
    T Get(Expression<Func<T, bool>> where);
    IEnumerable<T> GetAll();
    IEnumerable<T> GetMany(Expression<Func<T, bool>> where);
    void Commit();
}

抽象类（Repository.cs）：

 public abstract class Repository<T> : IRepository<T> where T : class
    {
        private Database_DBEntities dataContext;
        private readonly IDbSet<T> dbset;
        protected Repository(IDatabaseFactory databaseFactory)
        {
            DatabaseFactory = databaseFactory;
            dbset = DataContext.Set<T>();

        }

        /// <summary>
        /// Property for the databasefactory instance
        /// </summary>
        protected IDatabaseFactory DatabaseFactory
        {
            get;
            private set;
        }

        /// <summary>
        /// Property for the datacontext instance
        /// </summary>
        protected Database_DBEntities DataContext
        {
            get { return dataContext ?? (dataContext = DatabaseFactory.Get()); }
        }

        /// <summary>
        /// For adding entity
        /// </summary>
        /// <param name="entity"></param>
        public virtual void Add(T entity)
        {

            try
            {
                dbset.Add(entity);
                //  dbset.Attach(entity);
                dataContext.Entry(entity).State = EntityState.Added;
                int iresult = dataContext.SaveChanges();
            }
            catch (UpdateException ex)
            {

            }
            catch (DbUpdateException ex) //DbContext
            {

            }
            catch (Exception ex)
            {
                throw ex;
            }

        }

        /// <summary>
        /// For updating entity
        /// </summary>
        /// <param name="entity"></param>
        public virtual void Update(T entity)
        {
            try
            {
                // dbset.Attach(entity);
                dbset.Add(entity);
                dataContext.Entry(entity).State = EntityState.Modified;
                int iresult = dataContext.SaveChanges();
            }
            catch (UpdateException ex)
            {
                throw new ApplicationException(Database_ResourceFile.DuplicateMessage, ex);
            }
            catch (DbUpdateException ex) //DbContext
            {
                throw new ApplicationException(Database_ResourceFile.DuplicateMessage, ex);
            }
            catch (Exception ex) {
                throw ex;
            }
        }



        /// <summary>
        /// for deleting entity with class 
        /// </summary>
        /// <param name="entity"></param>
        public virtual void Delete(T entity)
        {
            dbset.Remove(entity);
            int iresult = dataContext.SaveChanges();
        }


        //To commit save changes
        public void Commit()
        {
            //still needs modification accordingly
            DataContext.SaveChanges();
        }

        /// <summary>
        /// Fetches values as per the int64 id value
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public virtual T GetById(long id)
        {
            return dbset.Find(id);
        }

        /// <summary>
        /// Fetches values as per the string id input
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public virtual T GetById(string id)
        {
            return dbset.Find(id);
        }

        /// <summary>
        /// fetches all the records 
        /// </summary>
        /// <returns></returns>
        public virtual IEnumerable<T> GetAll()
        {
            return dbset.AsNoTracking().ToList();
        }

        /// <summary>
        /// Fetches records as per the predicate condition
        /// </summary>
        /// <param name="where"></param>
        /// <returns></returns>
        public virtual IEnumerable<T> GetMany(Expression<Func<T, bool>> where)
        {
            return dbset.Where(where).ToList();
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="entity"></param>
        public void Detach(T entity)
        {
            dataContext.Entry(entity).State = EntityState.Detached;
        }

        /// <summary>
        /// fetches single records as per the predicate condition
        /// </summary>
        /// <param name="where"></param>
        /// <returns></returns>
        public T Get(Expression<Func<T, bool>> where)
        {
            return dbset.Where(where).FirstOrDefault<T>();
        }

    }

现在的重点是如何在控制器中访问此存储库模式，我们开始：

1.你有用户模型：

public partial class User
{
        public int Id { get; set; }
        public string Name { get; set; }
}

2。现在您必须创建 UserModel 的存储库类

public class UserRepository : Repository<User>, IUserRepository
{
    private Database_DBEntities dataContext;

    protected IDatabaseFactory DatabaseFactory
    {
        get;
        private set;
    }

    public UserRepository(IDatabaseFactory databaseFactory)
        : base(databaseFactory)
    {
        DatabaseFactory = databaseFactory;
    }

    protected Database_DBEntities DataContext
    {
        get { return dataContext ?? (dataContext = DatabaseFactory.Get()); }
    }

  public interface IUserRepository : IRepository<User>
  { 
  }
}

3.现在您必须使用所有 CRUD 方法创建 UserService 接口 (IUserService.cs)：

public interface IUserService
 {

     #region User Details 
     List<User> GetAllUsers();
     int SaveUserDetails(User Usermodel);
     int UpdateUserDetails(User Usermodel);
     int DeleteUserDetails(int Id);
     #endregion

}

4.现在您必须使用所有 CRUD 方法创建用户服务接口 (UserService.cs)：

public class UserService : IUserService
{
  IUserRepository _userRepository;
  public UserService() { }
  public UserService(IUserRepository userRepository)
  {
   this._userRepository = userRepository;
  }
  public List<User> GetAllUsers()
  {
      try
      {
          IEnumerable<User> liUser = _userRepository.GetAll();
          return liUser.ToList();
      }
      catch (Exception ex)
      {
          throw ex;
      }
  }
   /// <summary>
   /// Saves the User details.
   /// </summary>
   /// <param name="User">The deptmodel.</param>
   /// <returns></returns>
   public int SaveUserDetails(User Usermodel)
   {
       try
       {
           if (Usermodel != null)
           {
               _userRepository.Add(Usermodel);
               return 1;
           }
           else
               return 0;
       }
       catch
       {
           throw;
       }

   }

   /// <summary>
   /// Updates the User details.
   /// </summary>
   /// <param name="User">The deptmodel.</param>
   /// <returns></returns>
   public int UpdateUserDetails(User Usermodel)
   {
       try
       {
           if (Usermodel != null)
           {
               _userRepository.Update(Usermodel);
               return 1;
           }
           else
               return 0;
       }
       catch
       {
           throw;
       }
   }

   /// <summary>
   /// Deletes the User details.
   /// </summary>
   /// <param name="Id">The code identifier.</param>
   /// <returns></returns>
   public int DeleteUserDetails(int Id)
   {
       try
       {
           User Usermodel = _userRepository.GetById(Id);
           if (Usermodel != null)
           {
               _userRepository.Delete(Usermodel);
               return 1;
           }
           else
               return 0;
       }
       catch
       {
           throw;
       }
   }

}

5.现在你已经为你的存储库模式设置好了，你可以访问用户控制器中的所有数据：

//Here is the User Controller 
public class UserProfileController : Controller
{

    IUserService _userservice;
    public CustomerProfileController(IUserService userservice)
    {
        this._userservice = userservice;
    }

    [HttpPost]
    public ActionResult GetAllUsers(int id)
    {
    User objUser=new User();

    objUser = _userservice.GetAllUsers().Where(x => x.Id == id).FirstOrDefault();

    }
}

干杯！！