Entity FrameWork实现增、删、改、分页的数据层代码实现

public bool AddEntity(Customer entity)//添加实体

  {

      MyHotelModelContainer hotelDB = new MyHotelModelContainer();//定义上下文实体

      if (entity.Id == Guid.Empty)

      {

          entity.Id = Guid.NewGuid();

      }

      hotelDB.Customer.AddObject(entity);//调用添加实体方法

      int count = hotelDB.SaveChanges();

      if (count > 0)

      {

          return true;

      }

      return false;

  }

 

  public bool UpdateEntity(Customer entity)//更新实体

  {

      bool result = false;

      MyHotelModelContainer hotelDB = new MyHotelModelContainer();

      hotelDB.Customer.Attach(entity);

      hotelDB.ObjectStateManager.ChangeObjectState(entity, System.Data.EntityState.Modified);//调用更新实体发法

      int count = hotelDB.SaveChanges();

      if (count > 0)

      {

          result = true;

      }

      return result;

   

  }

 

  public bool DeleteEntity(Guid Id)//根具指定id删除一个实体

  {

      bool result = false;

      MyHotelModelContainer hoteDB = new MyHotelModelContainer();

      //根据id查询出要删除的实体

      var tempDelete = hoteDB.Customer.Where<Customer>(c => c.Id == Id).FirstOrDefault<Customer>();<span style="white-space:pre">    </span>

      if (tempDelete != null)//删除之前的判断

      {

          hoteDB.Customer.DeleteObject(tempDelete);//调用删除实体方法

          var count = hoteDB.SaveChanges();

          if (count > 0)

          result = true;

      }

      return result;

  }

 

  public IQueryable<Customer> GetByWhere(Func<Customer, bool> whereLambda)//根据某种条件等到实体集合  <span style="font-size:12px; font-family:Arial,Helvetica,sans-serif">IQueryable集合可以实现延迟加载功能</span>

  {<span style="white-space:pre">   </span>

      MyHotelModelContainer hoteDB = new MyHotelModelContainer();

      var temp = hoteDB.Customer.Where<Customer>(whereLambda).AsQueryable<Customer>();

      return temp;

  }

 

  public IQueryable<Customer> GetPageEntity(Func<Customer, bool> whereLambda, int? pageSize, int? pageIndex)//实现分页的方法

  {

      MyHotelModelContainer hotelDB = new MyHotelModelContainer();

      var temp = hotelDB.Customer

          .Where<Customer>(whereLambda)

          .OrderBy(c => c.FirstName)

          .Skip<Customer>(pageSize.Value * (pageIndex.Value - 1))

          .Take<Customer>(pageSize.Value)

          .AsQueryable<Customer>();

      return temp;

  }

 

 

  public long GetCount(Func<Customer, bool> whereLambda)//得到中共多少条数据

  {

      MyHotelModelContainer hotelDB = new MyHotelModelContainer();

      return hotelDB.Customer.Where<Customer>(whereLambda).Count();

  }