Can i do this with dynamic LInq or is there a better way - Linq, C#, VS2008

Question

This is my static query

    var results = from v in users
              join d in orders on v.UserId equals d.UserId
              join p in Products on d.ProductId equals p.ProductId
              where v.UserName.Contains(UserName)
              where v.FirstName.Equals(FirstName)
              where v.ZipCity.Equals(ZipCity)
              where v.OrderDate >= OrderDate && v.OrderDate < OrderDate
              where p.ProductName.Equals(ProductName)
              select v.Email, v.ShippingCity, v.TrackingNo;

I was looking at dynamic Linq and am trying to expand my feel on it. The above query is in a method called

GetOrder(string UserName, string FirstName, string ZipCity, DateTime OrderDate, ProductName)

Can I do this with Dynamic Linq, join to Products Table only if ProductName is not null in input parameter?

I was following this http://blog.bvsoftware.com/post/2008/02/27/How-to-create-a-Dynamic-LINQ-Query-Programmatically.aspx

Answer 1

Take a look at the answer I gave for this question:

http://stackoverflow.com/questions/893036/best-practices-for-building-a-search-app/893072#893072

Answer 2

I think I'd use extension methods on IEnumerable instead of Dynamic LINQ.

var result = from v in users
             join d in orders on v.UserId equals d.UserId
             where v.UserName.Contains(UserName)
             where v.FirstName.Equals(FirstName)
             where v.ZipCity.Equals(ZipCity)
             where v.OrderDate >= OrderDate && v.OrderDate < OrderDate
             select v.Email, v.ShippingCity, v.TrackingNo, d.ProductId;

if (!string.IsNullOrEmpty(ProductName))
{
   result = result.Join( Products.Where( p=> p.ProductName == ProductName ),
                         d => d.ProductId,
                         p => p.ProductId,
                         (d,p) => new
                                  {
                                      d.Email,
                                      d.ShippingCity,
                                      d.TrackingNo
                                  });
}