I saw already some of the similar questions, but cannot find an anwser how to solve this problem.
I want to have a possibility to order collection using string as property name.
Model:
User { string FullName; User SuperiorUser }
And I want to make a call like this:
DbSet.Order("SuperiorUser.FullName", Asc/Desc)...
My below functions work for a Order("FullName", Asc/Desc)
, but dont when I want to go deeper.
public static IOrderedQueryable<T> Order<T>(this IQueryable<T> source, string propertyName,
ListSortDirection direction = ListSortDirection.Ascending)
{
return ListSortDirection.Ascending == direction
? source.OrderBy(ToLambda<T>(propertyName))
: source.OrderByDescending(ToLambda<T>(propertyName));
}
private static Expression<Func<T, object>> ToLambda<T>(string propertyName)
{
var parameter = Expression.Parameter(typeof(T));
var property = Expression.Property(parameter, propertyName);
return Expression.Lambda<Func<T, object>>(property, parameter);
}
So I made it look a little bit like this
private static Expression<Func<T, object>> ToLambda<T>(string propertyName)
{
var propertyNames = propertyName.Split('.');
var type = typeof(T)
ParameterExpression parameter;
MemberExpression property;
for (var propName in propertyNames)
{
parameter = Expression.Parameter(type);
property = Expression.Property(parameter, propName);
type = property.Type;
}
return Expression.Lambda<Func<T, object>>(property, parameter);
}
But this unfortunately returns error The parameter '' was not bound in the specified LINQ to Entities query expression
. What am I missing?
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