Unable to cast object of type 'System.DBNull' to type 'System.Byte[]

[Thomas]

I am using RadBinaryImage control with SqlDataSource. If the VarBinary field contains a NULL value I am getting this error:  “Unable to cast object of type 'System.DBNull' to type 'System.Byte[]' “.

My understanding is that a NULL field should be cast to  a null or empty byte[].

Can someone please show me how check if the supplied value is of type DBNull and how to change it to appropriate empty byte array or null in C#?

Thanks,
Thomas

[BaiH]

Hey Thomas, I think you have missed the first thread in this forum ;) Here is a link.

--BH

[Thomas]

I have read the first thread and I understand that the field should be cast to null or empty byte[]. My question was: how to do it.  I would appreciate if someone would help me with an example in C# .

Thanks,
Thomas

[Growls]

to do it in markup:

 <telerik:RadBinaryImage runat="server" ID="rbi" DataValue='<%# ((System.Data.Linq.Binary) Eval("imageFull")).ToArray() %>' />

or do it dynamically:

var product = (from p in products
               select p).First();//.First() = LIMIT 1 in sql, which in turn makes the product variable singular and usable like this:
rsi.DataValue = product.imageFull.ToArray();

[Thomas]

Thank you Craig. This is what I was looking for.
Thomas

[Bodie Sullivan]

I am having the same issue but my project is in VB using .Net 2.0... What would the syntax be for VB with out using LINQ to convert a null value in the markup?

[Derek]

I'd like to see the solution in VB (and without using LINQ) as well. Anyone?

[Ilya Tryapitsin]

For VB without LINQ you can use IIf function.
For example:

 < asp:Repeater ID="Repeater1" runat="server" DataSourceID="SqlDataSource1">
    <ItemTemplate>
    ...
        <telerik:RadBinaryImage ID="RadBinaryImage1" runat="server" DataValue='<%#IIf(Typeof(Eval("photo")) is DBNull, Nothing, Eval("photo"))%>' />
    ...
     </ItemTemplate>

 

 

[Richard]

I think you should check the value containing DBNUll or not , You can check DBNull value using System.DBNull.Value , find the full source code to check DBNull value here :

http://net-informations.com/csprj/ado.net/cs-dbnull.htm

algr.

[syeada sanjida]

 when i can editing this message show .why this problem show unable to cast object of type system.dbnull to type 'system.byte[]