EF5 操作数据库,分离数据操作与业务逻辑

using Mvc.Entity;
using System;
using System.Collections.Generic;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
namespace Mvc.Dal
{
/// <summary>
/// 数据操作,泛型类
/// </summary>
/// <typeparam name="T">要操作的的表对应的实体类的类型</typeparam>
public class DalGeneric<T> where T : class,new()
{
MyMvcCmsEntities db = new MyMvcCmsEntities();
#region 1.0 新增实体 +int Add(T model)
public int Add(T model)
{
db.Set<T>().Add(model);
return db.SaveChanges();//保存成功后，会将自增的id设置给 model的主键属性，并返回受影响行数
}
#endregion
#region 2.0 根据id 删除实体 +int Del(T model)
public int Del(T model)
{
db.Set<T>().Attach(model); db.Set<T>().Remove(model); return db.SaveChanges();
}
#endregion
#region 3.0 根据条件删除 +int DelBy(Expression<Func<T, bool>> delWhere)
public int DelBy(Expression<Func<T, bool>> delWhere)
{ //3.1查询要删除的数据
List<T> listDeleting = db.Set<T>().Where(delWhere).ToList();
//3.2将要删除的数据用删除方法添加到 EF 容器中
listDeleting.ForEach(u =>
{
db.Set<T>().Attach(u);//先附加到 EF容器
db.Set<T>().Remove(u);//标识为删除状态
});
//3.3一次性生成sql语句到数据库执行删除
return db.SaveChanges();
}
#endregion
#region 4.0 修改 +int Modify(T model, params string[] proNames)
/// <summary>
/// 4.0 修改，如：
/// T u = new T() { uId = 1, uLoginName = "asdfasdf" };
/// this.Modify(u, "uLoginName");
/// </summary>
/// <param name="model"></param>
/// <param name="proNames"></param>
/// <returns></returns>
public int Modify(T model, params string[] proNames)
{
//4.1将对象添加到 EF中
DbEntityEntry entry = db.Entry<T>(model);
//4.2先设置对象的包装状态为 Unchanged
entry.State = System.Data.EntityState.Unchanged;
//4.3循环被修改的属性名数组
foreach (string proName in proNames)
{
//4.4将每个被修改的属性的状态设置为已修改状态;后面生成update语句时，就只为已修改的属性更新
entry.Property(proName).IsModified = true;
}
//4.5一次性生成sql语句到数据库执行
return db.SaveChanges();
}
#endregion
#region 4.x 批量修改 +int Modify(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames)
/// <summary>
/// 4.0 批量修改
/// </summary>
/// <param name="model">要修改的实体对象</param>
/// <param name="whereLambda">查询条件</param>
/// <param name="modifiedProNames">要修改的属性名称</param>
/// <returns></returns>
public int ModifyBy(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedProNames)
{
//4.1查询要修改的数据
List<T> listModifing = db.Set<T>().Where(whereLambda).ToList();
//获取实体类类型对象
Type t = typeof(T); // model.GetType();
//获取实体类所有的公有属性
List<PropertyInfo> proInfos = t.GetProperties(BindingFlags.Instance | BindingFlags.Public).ToList();
//创建实体属性字典集合
Dictionary<string, PropertyInfo> dictPros = new Dictionary<string, PropertyInfo>();
//将实体属性中要修改的属性名添加到字典集合中键：属性名值：属性对象
proInfos.ForEach(p => { if (modifiedProNames.Contains(p.Name)) { dictPros.Add(p.Name, p); } });
//4.3循环要修改的属性名
foreach (string proName in modifiedProNames)
{
//判断要修改的属性名是否在实体类的属性集合中存在
if (dictPros.ContainsKey(proName))
{
//如果存在，则取出要修改的属性对象
PropertyInfo proInfo = dictPros[proName];
//取出要修改的值
object newValue = proInfo.GetValue(model, null); //object newValue = model.uName;
//4.4批量设置要修改对象的属性
foreach (T usrO in listModifing)
{
//为要修改的对象的要修改的属性设置新的值
proInfo.SetValue(usrO, newValue, null); //usrO.uName = newValue;
}
}
}
//4.4一次性生成sql语句到数据库执行
return db.SaveChanges();
}
#endregion
#region 5.0 根据条件查询 +List<T> GetListBy(Expression<Func<T,bool>> whereLambda)
/// <summary>
/// 根据条件查询
/// </summary>
/// <param name="whereLambda"></param>
/// <returns></returns>
public List<T> GetListBy(Expression<Func<T, bool>> whereLambda)
{
return db.Set<T>().Where(whereLambda).ToList();
}
#endregion
#region 5.1 根据条件排序和查询 + List<T> GetListBy<TKey>
/// <summary>
/// 根据条件排序和查询
/// </summary>
/// <typeparam name="TKey"></typeparam>
/// <param name="whereLambda"></param>
/// <param name="orderLambda"></param>
/// <returns></returns>
public List<T> GetListBy<TKey>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda)
{
return db.Set<T>().Where(whereLambda).OrderBy(orderLambda).ToList();
}
#endregion
#region 5.2 根据条件查询一个实体 +T GetBy(Expression<Func<T, bool>> whereLambda)
/// <summary>
///
/// </summary>
/// <param name="whereLambda"></param>
/// <returns></returns>
public T GetBy(Expression<Func<T, bool>> whereLambda)
{
return db.Set<T>().Where(whereLambda).FirstOrDefault();
}
#endregion
#region 6.0 分页查询 + List<T> GetPagedList<TKey>
/// <summary>
/// 分页查询
/// </summary>
/// <typeparam name="TKey"></typeparam>
/// <param name="pageIndex"></param>
/// <param name="pageSize"></param>
/// <param name="whereLambda"></param>
/// <param name="orderBy"></param>
/// <returns></returns>
public List<T> GetPagedList<TKey>(int pageIndex, int pageSize, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderBy)
{
// 分页一定注意： Skip 之前一定要 OrderBy
return db.Set<T>().Where(whereLambda).OrderBy(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();
}
#endregion
}
}

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