Dynamic LINQ query against a List<> collection

[shollon]

I'm using C# 2010 .NET 4.0 and I have a List<T> collection returns that i needing to build a dynamic LINQ query on.

I'm utilizing the Predicate Builder referenced here


This works fine if I have 1 filter criteria, but if i have 2 or more, then, when the query.compile() is called, i get this error:

variable 'tmp' of type 'Check21Tools.IncomingReturn' referenced from scope '', but it is not defined


Code:

 Expression<Func<Check21Tools.IncomingReturn, bool>> query = null;

              bool hasFilterItems = false;
              if (filterArray != null)
              {
                foreach (string s in filterArray)
                {
                  if (s == string.Empty)
                  { break; }
                  else
                  {
                    hasFilterItems = true;
                    Int64 id = Int64.Parse(s);
                    query = query.Or(tmp => tmp.ID == id);
                  }

                }
              }
              if (hasFilterItems)
              {
                returns = returns.Where(query.Compile()).CreateFromEnumerable<Check21Tools.IncomingReturns, Check21Tools.IncomingReturn>();
              }

Code:

 public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expr1,
                                                        Expression<Func<T, bool>> expr2)
    {
      if (expr1 == null) return expr2;

      return Expression.Lambda<Func<T, bool>>
            (Expression.OrElse(expr1.Body, expr2.Body), expr1.Parameters);
      
    }