late binding in linq

Question

I have a simple LINQ query that is going against a collection.

   Dim oList = From w In Os
                Order By w.ClassTitle Descending
        Select w

What I'd like to be able to do though is pass into this whether it's descending or ascending. I'm not sure how to do that.

Also, if I were to have a where clause in here.. say

where w.ClassTitle = "Test"

How can I make the "Test so that I can pass it into the LINQ query.

Thanks shannon

Answer 1

Use delegation syntax. For example;

Dim oList = Os.Where(....).OrderBy(...)...

Answer 2

I dont think you can pass that "into" this query, however you could do the regular query

var oList = from w in Os
            select w

Then when the user takes some action you could simply do an order by after that fact.

oList.OrderBy(o => o.ClassTitle)

or

oList.OrderByDescending(o => o.ClassTitle)

UPDATE:

As far as the late binding, what you could do is write a method that would execute the Where clause. Perhaps using an extension method might work. I'm more familiar with C# so my syntax might be a bit off

public static IEnumerable<Os> ExecuteWhere (this Table<Os> table, Expression<Func<Os, bool>> predicate)
{
    return table.AsQueryable<Os>().Where(predicate);
}

Then to call it like so:

oList.ExecuteWhere(a => a.ClassTitle == "Test")