Question

I am relatively new to .Net and SQL Server and I need to be able to do a boolean check on a DateTime datatype for a null value.

I am using the following statement which is clearly wrong as it returns an Int32 in my Visual Studio immediate window while debugging. I am using linq to call a stored procedure which interrogates a bunch of tables.

The markup that some of the result collection will be bound to look like this;

<asp:Image  ID="imgAuthorised" ImageUrl='<%# (bool)DataBinder.Eval(Container.DataItem, "AuthorisedDate")?"/Horizon/Images/save16x16.png":"/Horizon/Images/delete16x16.png" %>' runat="server" ToolTip='<%# (bool)DataBinder.Eval(Container.DataItem, "AuthorisedDate")?"Authorised":"Not Authorised" %>' />

Depending on the boolean value of the collection returned then I want to display an appropriate image. Here is my attempt(ahem) to do an evaluation within the stored proc’

CASE WHEN dbo.Expense.AuthorisedDate is null THEN 0 ELSE 1 END as AuthorisedDate

I have tried casting this statement like so;

CAST(CASE WHEN dbo.Expense.AuthorisedDate is null THEN 0 ELSE 1 END as bit) as AuthorisedDate

Feel free to giggle at any school boy errors or poor understanding as I’m a dot net newb (hence the name :P) ha!

I would appreciate if someone could help me understand what I am doing wrong and what to do/avoid in future when attempting to do stuff like this.

TIA

dotnetnewb

Answer 1

what about extending your model? Your stored procedure (lets assume it’s called GetMyData) will likely return an ISingleResult.

If so, go to your DBML, view code (assuming this is a web application) and create a new partial class:

public partial class GetMyDataResults
{
    public bool IsAuthorised
    {
        get { return DateAuthorised.HasValue; }
    }
}

And then you should be able to:

<asp:Image ID="imgAuthorised" ImageUrl='<%# DataBinder.Eval(Container.DataItem, "IsAuthorised")?"/Horizon/Images/save16x16.png":"/Horizon/Images/delete16x16.png" %>' runat="server" ToolTip='<%# DataBinder.Eval(Container.DataItem, "IsAuthorised")?"Authorised":"Not Authorised" %>' />

Alternatively, you can piggyback onto the OnItemDataBinding event and do the work in there, though the above would be the easier path I’d think.

Cheers,
Terry