How does Select statement works in a Dynamic Linq Query? - asp.net-mvc

Question

1) I've a Product table with 4 columns: ProductID, Name, Category, and Price. Here's the regular linq to query this table.
public ActionResult Index()
{
private ProductDataContext db = new ProductDataContext();
var products = from p in db.Products
where p.Category == "Soccer"
select new ProductInfo { Name = p.Name, Price = p.Price}
return View(products);
}
Where ProductInfo is just a class that contains 2 properties (Name and Price). The Index page Inherits ViewPage - IEnumerable - ProductInfo. Everything works fine.
2) To dynamicaly execute the above query, I do this:
Public ActionResult Index()
{
var products =
db.Products
.Where("Category = \"Soccer\"")
.Select(/* WHAT SOULD I WRITE HERE TO SELECT NAME & PRICE?*/)
return View(products);
}
I'm using both 'System.Lind.Dynamic' namespace and the DynamicLibrary.cs (downloaded from ScottGu blog).
Here are my questions:
What expression do I use to select only Name and Price?
(Most importantly) How do I retrieve the data in my view? (i.e. What type the ViewPage inherits? ProductInfo?)
===================
EDIT
When I write .Select("new(Name, Price)"), I'm able to pass an object to the ViewData's Model property. Unfortunately, in order to use the Viewdata object, I'm asked to cast the Viewdata to a type. But, I do not know how to determine the type to do the casting.
====================
EDIT
Instead of the ViewData's Model property, I'm using simply the ViewData["products"]. To retrieve the content, I just place a IEnumerable cast before the ViewData, like this:
<% foreach(var item in (IEnumerable)ViewData["products"]){%>
<p><% = Html.Encode(item)%><p>
<%}%>
There are 2 situations:
1) If I select only one column (for instance, Name), everything work fine.
2) If I select more than 1 more columns (Name, Price), I get something like this
{Name=Soccer, Price=19.50}
{Name=Shin Pads, Price=11.59}
Why I just don't get something like
Soccer, 19.50
Shin Pads, 11.59
=================================
EDIT April 02 - 05h47 AM
I've define the GetPropertyValue Method (as your response suggets) as static in a static Class that I called 'HelperClass'. Now, this is the way I try to access the value of Name from my object.
<% = Html.Encode(HelperClass.GetPropertyValue(ViewData["product"], "Name")) %>
I get the following Exception:"Object reference not set to an instance of an object". And, the following line from the inside GetPropertyValue() his highlight.
Line 22: return propInfo.GetValue(obj, null);
Do I need to use new keyword? (where?)
Thanks for helping

Answer 1

Private Sub filter()
Dim coll = db.Products.Where(Function(x) x.Category.Equals("Soccer")) _
.Select(Function(x) GetObject(x.Name, x.Price))
End Sub
Private Function GetObject(ByVal name As String, ByVal price As String) As Object
Return new ProductInfo(name, price)
End Function

Answer 2

1) To generate a new projection type at runtime you can:
.Select("new(Name, Price)")
2) To read values from the object, you need to use reflection:
string name = GetPropertyValue(someObject, "Name");
...
public static object GetPropertyValue(object obj, string propName)
{
System.Reflection.PropertyInfo propInfo = obj.GetType().GetProperty(propName);
return propInfo.GetValue(obj, null);
}