现在是附加的,组合查询需要的扩展类。大家知道lanmda表达式的组合条件比较麻烦,所以就加了一样一个类,方便进行组合查询:
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Linq.Expressions; namespace JFrame.AccessCommon { public static class PredicateExtensions { public static Expression<Func<T, bool>> True<T>() { return f => true; } public static Expression<Func<T, bool>> False<T>() { return f => false; } public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expression1, Expression<Func<T, bool>> expression2) { var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast<Expression>()); return Expression.Lambda<Func<T, bool>>(Expression.Or(expression1.Body, invokedExpression), expression1.Parameters); } public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expression1, Expression<Func<T, bool>> expression2) { var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast<Expression>()); return Expression.Lambda<Func<T, bool>>(Expression.And(expression1.Body, invokedExpression), expression1.Parameters); } } }
Entity Framework底层操作封装V2版本(3),布布扣,bubuko.com
原文地址:http://blog.csdn.net/jacky4955/article/details/25412261