学习笔记: Expression表达式目录树详解和扩展封装

1. 表达式链接扩展封装,ORM常用 And  Or

/// <summary>

/// 表达式访问者

/// </summary>

public class ExpressionVisitorTest

{

public static void Show()
     {

#region 表达式链接
         {
             Expression<Func<People, bool>> lambda1 = x => x.Age > 5;
             Expression<Func<People, bool>> lambda2 = x => x.Id > 5;
             Expression<Func<People, bool>> lambda3 = lambda1.And(lambda2);
             Expression<Func<People, bool>> lambda4 = lambda1.Or(lambda2);
             Expression<Func<People, bool>> lambda5 = lambda1.Not();
             Do1(lambda3);
             Do1(lambda4);
             Do1(lambda5);
         }
         #endregion

}
     #region PrivateMethod
     private static void Do1(Func<People, bool> func)
     {
         List<People> people = new List<People>();
         people.Where(func);
     }
     private static void Do1(Expression<Func<People, bool>> func)
     {
         List<People> people = new List<People>()
         {
             new People(){Id=4,Name="123",Age=4},
             new People(){Id=5,Name="234",Age=5},
             new People(){Id=6,Name="345",Age=6},
         };

List<People> peopleList = people.Where(func.Compile()).ToList();
     }

private static IQueryable<People> GetQueryable(Expression<Func<People, bool>> func)
     {
         List<People> people = new List<People>()
         {
             new People(){Id=4,Name="123",Age=4},
             new People(){Id=5,Name="234",Age=5},
             new People(){Id=6,Name="345",Age=6},
         };

return people.AsQueryable<People>().Where(func);
     }
     #endregion

}