Created
August 25, 2010 15:17
-
-
Save carlhoerberg/549690 to your computer and use it in GitHub Desktop.
Dynamic LINQ OrderBy extension method
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
public static class QuerableExtensions | |
{ | |
public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string property, bool asc) | |
{ | |
return ApplyOrder<T>(source, property, asc ? "OrderBy" : "OrderByDescending"); | |
} | |
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; | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment