title: $filter option for DateTime in WCF Data Services query URL
body: <p>WCF Data Services conveniently allow querying and filtering data via options in the URL.  For example, say I want Products with a price greater than 20:</p>
  
  <blockquote>
    <p><a href="http://www.example.com/Service.svc/Products" rel="noreferrer">http://www.example.com/Service.svc/Products</a>?$filter=Price gt 20</p>
  </blockquote>
  
  <p>But how do I use the <code>$filter</code> option with a <code>DateTime</code>?  Say I want all Products that have been modified this month.</p>
  
  <blockquote>
    <p><a href="http://www.example.com/Service.svc/Products" rel="noreferrer">http://www.example.com/Service.svc/Products</a>?$filter=ModifiedDate gt '2012-05-02'</p>
  </blockquote>
  
  <p>This doesn't work for me; it gives the error message</p>
  
  <blockquote>
    <p>Operator 'gt' incompatible with operand types 'System.DateTime' and 'System.String' at position 13.</p>
  </blockquote>
  
  <p>I get the same with other comparison operators (ge, lt, le, eq).  What is going on?  How do I make this work?  Do I need a certain DateTime format?  What I tried above seems to be documented <a href="http://blogs.msdn.com/b/marcelolr/archive/2008/01/10/filter-query-option-in-ado-net-data-services.aspx" rel="noreferrer">here</a>.</p>