writing a dynamic Query?

Hi,

I try to write a search-panel. I have a panel with some comboboxes and textfields.

after clicking the search-button, it should start something like this:

 string[,] searchlist = new string[100,100];

 if (cbbWorkflowState.SelectedItem != null) { searchlist.SetValue(new string[2] { cbbWorkflowState.SelectedItem.ToString(), "Status" }, index); index++; }

 if (txtOrderRef.Text != "") { searchlist.SetValue(new string[2] { txtOrderRef.Text, "Reference" }, index); index++; }

in this array is in first dimension the search string, the second is the entity property 

try {
        using (ModelUnitOfWork uow = Service.DatabaseService.CreateUnitOfWork()) {
            string where_list = "";
            int count = 1;
                foreach (string search in searchlist)
                {
                where_list += "tv=>tv."+ search[1] +" == "+ search[0];
                if (searchlist.Length != count)
                {
                    where_list += " && ";
                }
            }
           IQueryable<TransportOrder> tempTransports;
          tempTransports = uow.TransportOrders.Where(where_list);

this doesn't work, exception is that the where-method has invalid arguments.

sorry for double-post, i got an error message and thougt, it wasn't send

A LINQ query requires an expression.  Such expressions are generated by the C# compiler when you compile LINQ code.  You cannot pass a string of C# source code at runtime because the compiler is out of the loop by then -- LINQ engines do not contain their own built-in compilers and will not parse source code for you.

For composing queries at runtime based on strings, you can either use query objects and the Entity.Attribute(attrName) syntax (see http://www.mindscapehq.com/documentation/lightspeed/Basic-Operations/Querying-the-Database-Using-Query-Objects) or use one of the various 'dynamic LINQ' toolkits (e.g. http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx).

By the way, the forums error message occurs because you have entered an invalid email address -- unfortunately our forums engine does not handle this at all well!