zoukankan      html  css  js  c++  java
  • Dynamic LINQ OrderBy

     public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string property)
        {
            return ApplyOrder<T>(source, property, "OrderBy");
        }
        public static IOrderedQueryable<T> OrderByDescending<T>(this IQueryable<T> source, string property)
        {
            return ApplyOrder<T>(source, property, "OrderByDescending");
        }
        public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string property)
        {
            return ApplyOrder<T>(source, property, "ThenBy");
        }
        public static IOrderedQueryable<T> ThenByDescending<T>(this IOrderedQueryable<T> source, string property)
        {
            return ApplyOrder<T>(source, property, "ThenByDescending");
        }
        static IOrderedQueryable<T> ApplyOrder<T>(IQueryable<T> source, string property, string methodName) {
            string[] props = property.Split('.');
            Type type = typeof(T);
            ParameterExpression arg = Expression.Parameter(type, "x");
            Expression expr = arg;
            foreach(string prop in props) {
                // use reflection (not ComponentModel) to mirror LINQ
                PropertyInfo pi = type.GetProperty(prop);
                expr = Expression.Property(expr, pi);
                type = pi.PropertyType;
            }
            Type delegateType = typeof(Func<,>).MakeGenericType(typeof(T), type);
            LambdaExpression lambda = Expression.Lambda(delegateType, expr, arg);
    
            object result = typeof(Queryable).GetMethods().Single(
                    method => method.Name == methodName
                            && method.IsGenericMethodDefinition
                            && method.GetGenericArguments().Length == 2
                            && method.GetParameters().Length == 2)
                    .MakeGenericMethod(typeof(T), type)
                    .Invoke(null, new object[] {source, lambda});
            return (IOrderedQueryable<T>)result;
       } 
  • 相关阅读:
    Hive中频繁报警的问题
    Hadoop中Namenode的HA查询和切换
    昨天面试遇到的一道C语言题
    【转】MapReduce的优化
    关于linux修改max user processes limits的问题
    Hadoop-2.6.0安装文档
    C#使用RabbitMQ
    windows配置Erlang环境
    【转】linux查看及修改文件权限以及相关
    (转)C#图解—PictureBox.SizeMode 属性
  • 原文地址:https://www.cnblogs.com/hyl8218/p/3164000.html
Copyright © 2011-2022 走看看