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~