How to Handle Null Value from <%# Bind(...

I am trying to retrieve the values for a selected row in a FormView to allow editing. One of the fields ("photo") can be null and when the following statement gets executed it throws an error that it cannot convert a null to an integer.

<gs:PhotopickerID="Photopicker1"runat="server"ImageId='<%# Bind("photo") %>'/>

I recall that in 1.1 I could replace the olde EVAL with a function that could check for a null and return a zero instead? Can that be done here, and if so, what is the syntax?

Hi Wayne,

Bind is a two-way data operation -- is that what you are trying to use with this?

Otherwise, you could just do an <%# Eval( CallSomeFunction("photo")) %> and define the "CallSomeFunction" (or another name) on your page or control to convert it to an appropriate value.

Alternatively, you could define ImageId on the control to accept null and handle the conversion there.

Hope this helps,

Scott

I am actually trying to modify the Club Starter Kit so most of the original code is from that kit. I did figure out that Bind was a 2 way process and I believe that the way that is written, the 2 way binding is necessary. I guess I may have to re-code that whole section?

Could you expand on defining Imageid on the control? I am not familiar with that approach.

Assuming you are talking about the control defined in photos_formpicker.ascx:

The easiest fix is to add a new property to the control for the ImageID, and have it take object rather than string. You could change the type on the existing property, but you'd then also have to change the code throughout the control. This way you just need to change the property name used to bind to the database from ImageID to PhotoImageID:

constint DEFAULTIMAGEID = 0;

privateint ImageId

{

get

{

EnsureChildControls();

if (viewswitch.ActiveViewIndex == 1)

{

returnConvert.ToInt32(selectedimage.Value);

}

else

{

object id = ViewState["ImageID"];

if (id ==null)

{

ViewState["ImageID"] = DEFAULTIMAGEID;

return DEFAULTIMAGEID;

}

else

{

returnConvert.ToInt32(id);

}

}

}

set { ViewState["ImageID"] =value; }

}

publicobject PhotoImageID

{

get {return ImageId; }

set { ViewState["ImageID"] = (value ==DBNull.Value) ? DEFAULTIMAGEID :Convert.ToInt32(value); }

}

Thank you very much. That is all a little beyond my current understanding so I'll have to do a bit of reading to make sure I impliment it correctly.

I appreciate the very complete response.