EF的泛型封装 写的很好 转自Fly_Elephant http://www.cnblogs.com/xiaofeixiang/p/4188600.html?utm_source=tuicool

Entity Framework本身的增删改查其实 已经很方便了，不过做项目的时候用的多了也就觉得有点累了，每个业务实体基本上都涉及到到了增删改查这四个基本的要素，至于封装每个公司可能都不一样，接口，设计模式都用的眼花缭乱，我闲来没事就搞个简单的封装Helper，Github上也有关于EF的扩展Libray，具体没有用过，公司的有自己的封装，自己也没怎么弄，具体地址:https://github.com/loresoft/EntityFramework.Extended.

首先来看段代码，model和context是从数据中直接生成，你可以选择自己习惯的方式:

//新增
User addUser = new User();
addUser.PersonID = 3;
addUser.UserName = "keso";
dbContext.Entry<User>(addUser).State = EntityState.Added;
dbContext.SaveChanges();
//修改
User updateUser = new User();
dbContext.Users.Where(item => item.ID == 2).OrderBy(item => item.ID);
updateUser.UserName = updateUser.UserName + "测试";
dbContext.Entry<User>(updateUser).State = EntityState.Modified;
dbContext.SaveChanges();
//删除
User delUser = dbContext.Users.Where(item => item.ID == 2).First();
dbContext.Entry<User>(delUser).State = EntityState.Deleted;
dbContext.SaveChanges();

如果每个业务实体都这么写一遍，估计公司水准有待提高，而且开发的也该跳起来骂人，本人只是简单封装下新建一个EFHelper，实际开发会封装的更多，不过底层处理是不变的

class EFHelpler<T> where T : class
{
//...
}

新增

方法:

/// <summary>
/// 实体新增
/// </summary>
/// <param name="model"></param>
public void add(params T[] paramList)
{
foreach (var model in paramList)
{
dbContext.Entry<T>(model).State = EntityState.Added;
}
dbContext.SaveChanges();
}

调用:

EFHelpler<User> helper = new EFHelpler<User>();
BaseContext dbContext = new BaseContext();
//新增
List<User> listUser = new List<User>();
for (int i = 0; i < 2; i++)
{
User user = new User();
user.PersonID = i;
user.UserName = "FlyElehant" + i;
listUser.Add(user);
}
helper.add(listUser.ToArray());
Console.WriteLine("新增成功");

查询

查询分了两种，一种是简单的查询，一种是分页的：

/// <summary>
/// 实体查询
/// </summary>
public IEnumerable<T> getSearchList(System.Linq.Expressions.Expression<Func<T, bool>> where)
{
return dbContext.Set<T>().Where(where);
}
/// <summary>
/// 实体分页查询
/// </summary>
/// <typeparam name="TKey"></typeparam>
/// <param name="where"></param>
/// <param name="orderBy"></param>
/// <param name="pageSize"></param>
/// <param name="pageIndex"></param>
/// <returns></returns>
public IEnumerable<T> getSearchListByPage<TKey>(Expression<Func<T, bool>> where, Expression<Func<T, TKey>> orderBy, int pageSize, int pageIndex)
{
return dbContext.Set<T>().Where(where).OrderByDescending(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize);
}

简单调用，第二个方式除了分页之外，主要是查询的时候指定一定OrderBy的类型，也就是TKey:

var query = helper.getSearchList(item => item.UserName.Contains("keso"));
var queryMulti = helper.getSearchListByPage<int>(item => item.UserName.Contains("FlyElehant"), order => order.PersonID, 2, 1);
query = queryMulti;
foreach (User user in query)
{
Console.WriteLine(user.UserName);
}

修改

修改代码稍微读了几行，主要是用到了一下反射:

/// <summary>
/// 按照条件修改数据
/// </summary>
/// <param name="where"></param>
/// <param name="dic"></param>
public void update(Expression<Func<T, bool>> where, Dictionary<string, object> dic)
{
IEnumerable<T> result = dbContext.Set<T>().Where(where).ToList();
Type type = typeof(T);
List<PropertyInfo> propertyList = type.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance).ToList();
//遍历结果集
foreach (T entity in result)
{
foreach (PropertyInfo propertyInfo in propertyList)
{
string propertyName = propertyInfo.Name;
if (dic.ContainsKey(propertyName))
{
//设置值
propertyInfo.SetValue(entity, dic[propertyName], null);
}
}
}
dbContext.SaveChanges();
}

调用:

Dictionary<string,object> dic=new Dictionary<string,object>();
dic.Add("PersonID",2);
dic.Add("UserName","keso");
helper.update(item => item.UserName.Contains("keso"), dic);
Console.WriteLine("修改成功");

删除

方法:

/// <summary>
/// 实体删除
/// </summary>
/// <param name="model"></param>
public void delete(params T[] paramList)
{
foreach (var model in paramList)
{
dbContext.Entry<T>(model).State = EntityState.Deleted;
}
dbContext.SaveChanges();
}

调用:

var query = helper.getSearchList(item => item.UserName.Contains("keso"));
helper.delete(query.ToArray());

完整的EFHelper:

class EFHelpler<T> where T : class
{
BaseContext dbContext = new BaseContext();
/// <summary>
/// 实体新增
/// </summary>
/// <param name="model"></param>
public void add(params T[] paramList)
{
foreach (var model in paramList)
{
dbContext.Entry<T>(model).State = EntityState.Added;
}
dbContext.SaveChanges();
}/// <summary>
/// 实体查询
/// </summary>
public IEnumerable<T> getSearchList(System.Linq.Expressions.Expression<Func<T, bool>> where)
{
return dbContext.Set<T>().Where(where);
}
/// <summary>
/// 实体分页查询
/// </summary>
/// <typeparam name="TKey"></typeparam>
/// <param name="where"></param>
/// <param name="orderBy"></param>
/// <param name="pageSize"></param>
/// <param name="pageIndex"></param>
/// <returns></returns>
public IEnumerable<T> getSearchListByPage<TKey>(Expression<Func<T, bool>> where, Expression<Func<T, TKey>> orderBy, int pageSize, int pageIndex)
{
return dbContext.Set<T>().Where(where).OrderByDescending(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize);
}/// <summary>
/// 实体删除
/// </summary>
/// <param name="model"></param>
public void delete(params T[] paramList)
{
foreach (var model in paramList)
{
dbContext.Entry<T>(model).State = EntityState.Deleted;
}
dbContext.SaveChanges();
}/// <summary>
/// 按照条件修改数据
/// </summary>
/// <param name="where"></param>
/// <param name="dic"></param>
public void update(Expression<Func<T, bool>> where, Dictionary<string, object> dic)
{
IEnumerable<T> result = dbContext.Set<T>().Where(where).ToList();
Type type = typeof(T);
List<PropertyInfo> propertyList = type.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance).ToList();
//遍历结果集
foreach (T entity in result)
{
foreach (PropertyInfo propertyInfo in propertyList)
{
string propertyName = propertyInfo.Name;
if (dic.ContainsKey(propertyName))
{
//设置值
propertyInfo.SetValue(entity, dic[propertyName], null);
}
}
}
dbContext.SaveChanges();
}}

个人Demo难免有表达不当或者技术失误的地方，如有不当，请多多指出，感激不尽~