注：这里的增删改操作并不即时进行，而是在封装在数据会话层中，以实现工作单元模式，提高数据库的操作效率。
考虑到每个类都需要实现相同的数据操作，我们可以将以上方法封装到一个泛型基类中，各类型只需要继承泛型基类就可以实现以上方法：
BaseDal.cs
using System;
using System.Data.Entity;
using System.Linq;
namespace PMS.DAL
{
public class BaseDal<T> where T:class ,new()
{
public DbContext DbEntities = DbContextFactory.CreateContext();
/// <summary>
/// 查询过滤
/// </summary>
/// <param name="whereLamada">过滤条件Lambda表达式</param>
/// <returns>实体集合</returns>
public IQueryable<T> LoadEntities(System.Linq.Expressions.Expression<Func<T, bool>> whereLamada)
{
return DbEntities.Set<T>().Where(whereLamada);
}
/// <summary>
/// 分页查询
/// </summary>
/// <typeparam name="TS">排序类型</typeparam>
/// <param name="pageIndex">查询的页码</param>
/// <param name="pageSize">每页显示的数目</param>
/// <param name="totalCount">符合条件的总行数</param>
/// <param name="whereLambda">过滤条件Lambda表达式</param>
/// <param name="orderbyLambda">排序Lambda表达式</param>
/// <param name="isAsc">排序方向</param>
/// <returns>实体集合</returns>
public IQueryable<T> LoadPageEntities<TS>(int pageIndex, int pageSize, out int totalCount, System.Linq.Expressions.Expression<Func<T, bool>> whereLambda, System.Linq.Expressions.Expression<Func<T, TS>> orderbyLambda, bool isAsc)
{
var temp = DbEntities.Set<T>().Where(whereLambda);
totalCount = temp.Count();
temp = isAsc ? temp.OrderBy(orderbyLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize) : temp.OrderByDescending(orderbyLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize);
return temp;
}
/// <summary>
/// 删除数据
/// </summary>
/// <param name="entity">待删数据</param>
/// <returns>删除结果</returns>
public bool DeleteEntity(T entity)
{
DbEntities.Entry(entity).State = EntityState.Deleted;
return true;
}
/// <summary>
/// 编辑数据
/// </summary>
/// <param name="entity">待编辑数据</param>
/// <returns>编辑结果</returns>
public bool EditEntity(T entity)
{
DbEntities.Entry(entity).State = EntityState.Modified;
return true;
}
/// <summary>
/// 添加数据
/// </summary>
/// <param name="entity">待添加数据</param>
/// <returns>已添加数据</returns>
public T AddEntity(T entity)
{
entity = DbEntities.Set<T>().Add(entity);
//DbEntities.SaveChanges();
return entity;
}
}
}
