ASP .NET, LINQ, GridViews, and GUID Errors

I found a simple problem today. Here is the deal, there were several times where I had to base a LinqDataSource off a Guid that I would set in the Page_Load(). I created an<asp:HiddenField /> to hold the value so all my DataSources could pull it from the control. The HiddenField control’s value is stored as a string, so I would have to convert the guid to a string. After doing this, I was getting the following error:

Operator ‘==’ incompatible with operand types ‘Guid’ and ‘String’

After looking around in my code and some forums, I found the answer: Linq is strongly cast and Visual Studio 2008 most like set the “where” clause to something like this:

<asp:LinqDataSource ID=“ldsProducs” runat=“server”

    ContextTypeName="CartDataContext" EnableDelete="True" EnableInsert="True"

    EnableUpdate="True" OrderBy="Product_UPC1" TableName="Product_UPCs"

    Where="Product_IID == @Product_IID">

    <WhereParameters>

        <asp:ControlParameter ControlID="hfProductIID" Name="Product_IID"

            PropertyName="Value" Type="Object" />

    </WhereParameters>

</asp:LinqDataSource>

However, because Linq is strongly cast you can’t perform an == operand on a String and Guid, so I changed the following:

<asp:LinqDataSource ID=“ldsProducs” runat=“server”

    ContextTypeName="CartDataContext" EnableDelete="True" EnableInsert="True"

    EnableUpdate="True" OrderBy="Product_UPC1" TableName="Product_UPCs"

    Where="Product_IID == Guid(@Product_IID)">

    <WhereParameters>

        <asp:ControlParameter ControlID="hfProductIID" Name="Product_IID"

            PropertyName="Value" Type="Object" />

    </WhereParameters>

</asp:LinqDataSource>

Now it’ll convert the HiddenField’s value to a Guid and compair.