Just add the following extension to your code and you're good to go:
using System.Linq;
using System.Linq.Expressions;
using System;
namespace SomeNameSpace
{
public static class SomeExtensionClass
{
public static IQueryable<T> OrderByField<T>(this IQueryable<T> q, string SortField, bool Ascending)
{
var param = Expression.Parameter(typeof(T), "p");
var prop = Expression.Property(param, SortField);
var exp = Expression.Lambda(prop, param);
string method = Ascending ? "OrderBy" : "OrderByDescending";
Type[] types = new Type[] { q.ElementType, exp.Body.Type };
var mce = Expression.Call(typeof(Queryable), method, types, q.Expression, exp);
return q.Provider.CreateQuery<T>(mce);
}
}
}
Usage:
.OrderByField(sortcriteria, true)
Edit:
For support for the ThenBy
method however the following methods returning an IOrderedQueryable
should take care of it all:
public static class SomeExtensionClass
{
private static IOrderedQueryable<T> OrderingHelper<T>(IQueryable<T> source, string propertyName, bool descending, bool anotherLevel)
{
var param = Expression.Parameter(typeof(T), "p");
var property = Expression.PropertyOrField(param, propertyName);
var sort = Expression.Lambda(property, param);
var call = Expression.Call(
typeof(Queryable),
(!anotherLevel ? "OrderBy" : "ThenBy") + (descending ? "Descending" : string.Empty),
new[] { typeof(T), property.Type },
source.Expression,
Expression.Quote(sort));
return (IOrderedQueryable<T>)source.Provider.CreateQuery<T>(call);
}
public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string propertyName)
{
return OrderingHelper(source, propertyName, false, false);
}
public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string propertyName, bool descending)
{
return OrderingHelper(source, propertyName, descending, false);
}
public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string propertyName)
{
return OrderingHelper(source, propertyName, false, true);
}
public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string propertyName, bool descending)
{
return OrderingHelper(source, propertyName, descending, true);
}
}
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…