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How can I use Where<T> extension method when T is unknown at compile time

IEnumerable<object> NewValueSubCollection = (IEnumerable<object>)NewValue.GetType().GetProperty(col.Name).GetValue(NewValue, null);

//Where col is a property of an object of type (IEnumerable<???>)

 

foreach (var line in ((IEnumerable<object>)col.GetValue(originalEntity, null)).ToList<object>())

{

    Type lineType = ObjectContext.GetObjectType(line.GetType());

    var lineEntitySet = context.GetEntitySet(lineType);

    EntityKey lineKey = context.CreateEntityKey(lineEntitySet.Name, line);

    if (NewValueSubCollection.Where(lineKey).Count() == 0) //See bellow

    context.DeleteObject(line);

}

       

public static class LinqExtension

{

    //Enable searching in a collection is an entity Key exist... and retrieve info.

    public static IEnumerable<T> Where<T>(this IEnumerable<T> source,EntityKey key)

    {

        return Enumerable.Where(source, CreateFilterExpressionBasedOnKey<T>(key).Compile());

    }

 

    private static Expression<Func<TInput, bool>> CreateFilterExpressionBasedOnKey<TInput>(Type sourceType, EntityKey key)

    {

        var param = Expression.Parameter(sourceType, "");

 

        Expression myFilter = Expression.Constant(true);

        if (key != null)

        {

            foreach (var item in key.EntityKeyValues)

            {

                Expression Left = Expression.PropertyOrField(param, item.Key.ToString());

                Expression Right = Expression.Constant(item.Value);

 

                myFilter = Expression.AndAlso(myFilter, Expression.Equal(Left, Right));

            }

        }

        return Expression.Lambda<Func<TInput, bool>>(myFilter, param);

    }

}

       

Type generic = typeof(Collection<>);

Type typeArgs = (NewValue.GetType().GetProperty(col.Name).GetValue(NewValue, null)).GetType().GetGenericArguments()[0];

Type constructed = generic.MakeGenericType(typeArgs);

object o = Activator.CreateInstance(constructed);

o = NewValue.GetType().GetProperty(col.Name).GetValue(NewValue, null);

       

if (o.Where(lineKey).Count() == 0) //error!!!

// 'object' does not contain a definition for 'Where' acception a first argument of type 'object' could be found (are you missing directive or an assembly reference?)

       

NewValueSubCollection.Where(lineKey).Count() == 0

       

NewValueSubCollection.Cast<dynamic>().Where(d => lineKey(d)).Count() == 0

       

!NewValueSubCollection.Cast<dynamic>().Any(d => lineKey(d))

       

class Program

{

    static void Main(string[] args)

    {

        var list = new List<string>();

        IEnumerable<object> objects = list;

        Func<string, bool> func = s => s.Contains("x");

 

        list.Add("Test");

        list.Add("x");

        list.Add("mux");

        foreach (var item in objects.Cast<dynamic>().Where(d => func(d)))

            Console.WriteLine(item);

        Console.ReadKey();

    }

}