Lambda表达式按字段名字排序

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;

 static class LinqExtensions
 {
     private static PropertyInfo GetPropertyInfo(Type objType, string name)
     {
         var properties = objType.GetProperties();
         var matchedProperty = properties.FirstOrDefault(p => p.Name == name);
         if (matchedProperty == null)
             throw new ArgumentException("name");

         return matchedProperty;
     }
     private static LambdaExpression GetOrderExpression(Type objType, PropertyInfo pi)
     {
         var paramExpr = Expression.Parameter(objType);
         var propAccess = Expression.PropertyOrField(paramExpr, pi.Name);
         var expr = Expression.Lambda(propAccess, paramExpr);
         return expr;
     }

     public static IEnumerable<T> OrderBy<T>(this IEnumerable<T> query, string name)
     {
         var propInfo = GetPropertyInfo(typeof(T), name);
         var expr = GetOrderExpression(typeof(T), propInfo);

         var method = typeof(Enumerable).GetMethods().FirstOrDefault(m => m.Name == "OrderBy" && m.GetParameters().Length == );
         var genericMethod = method.MakeGenericMethod(typeof(T), propInfo.PropertyType);
         return (IEnumerable<T>)genericMethod.Invoke(null, new object[] { query, expr.Compile() });
     }

     public static IQueryable<T> OrderBy<T>(this IQueryable<T> query, string name)
     {
         var propInfo = GetPropertyInfo(typeof(T), name);
         var expr = GetOrderExpression(typeof(T), propInfo);

         var method = typeof(Queryable).GetMethods().FirstOrDefault(m => m.Name == "OrderBy" && m.GetParameters().Length == );
         var genericMethod = method.MakeGenericMethod(typeof(T), propInfo.PropertyType);
         return (IQueryable<T>)genericMethod.Invoke(null, new object[] { query, expr });
     }

     public static IEnumerable<T> OrderByDescending<T>(this IEnumerable<T> query, string name)
     {
         var propInfo = GetPropertyInfo(typeof(T), name);
         var expr = GetOrderExpression(typeof(T), propInfo);

         var method = typeof(Enumerable).GetMethods().FirstOrDefault(m => m.Name == "OrderByDescending" && m.GetParameters().Length == );
         var genericMethod = method.MakeGenericMethod(typeof(T), propInfo.PropertyType);
         return (IEnumerable<T>)genericMethod.Invoke(null, new object[] { query, expr.Compile() });
     }

     public static IQueryable<T> OrderByDescending<T>(this IQueryable<T> query, string name)
     {
         var propInfo = GetPropertyInfo(typeof(T), name);
         var expr = GetOrderExpression(typeof(T), propInfo);

         var method = typeof(Queryable).GetMethods().FirstOrDefault(m => m.Name == "OrderByDescending" && m.GetParameters().Length == );
         var genericMethod = method.MakeGenericMethod(typeof(T), propInfo.PropertyType);
         return (IQueryable<T>)genericMethod.Invoke(null, new object[] { query, expr });
     }
 }

用法:

var r = new List<temp> {
    new temp { a =  },
    new temp { a =  },
    new temp { a =  }
}.OrderBy("a");

来源:https://stackoverflow.com/questions/32061770/call-orderby-with-a-field-name-as-a-string