problem with checking null or empty value in detailsview

[bob]

Hi,

i want to check whether the textbox of the detailsview is not left empty, in
insert mode.
I did this:

Protected Sub DetailsView1_It emInserting(ByV al sender As Object, ByVal e As
System.Web.UI.W ebControls.Deta ilsViewInsertEv entArgs) Handles
DetailsView1.It emInserting
Dim h As String
h = e.Values("myfie ld")
'If h = "" Then
If h Is Nothing Then
e.Cancel = True
Label1.Text = "may not be empty."
End If
End Sub

I tried two ways (with ="" and with is nothing), but in both cases, i always
get the label text and the event is always cancelled, even when i full some
value.

So, what's wrong with this code?

Thanks
Bob

[Armin Zingler]

Re: problem with checking null or empty value in detailsview

"bob" <bob@gh.vbschri eb

Hi,
>
i want to check whether the textbox of the detailsview is not left
empty, in insert mode.
I did this:
>
Protected Sub DetailsView1_It emInserting(ByV al sender As Object,
ByVal e As System.Web.UI.W ebControls.Deta ilsViewInsertEv entArgs)
Handles
DetailsView1.It emInserting
Dim h As String
h = e.Values("myfie ld")
'If h = "" Then
If h Is Nothing Then
e.Cancel = True
Label1.Text = "may not be empty."
End If
End Sub
>
I tried two ways (with ="" and with is nothing), but in both cases,
i always get the label text and the event is always cancelled, even
when i full some value.
>
So, what's wrong with this code?

First, you should enable Option Strict. The assignment

h = e.Values("myfie ld")

is not valid.

Then, you can examine the return value of e.Values. Maybe it is
DBNull.Value. If it is, you can do the comparison:

Dim Value as object
value = e.Values("myfie ld")

if value is dbnull.value then
'...
end if

If it's any other value, you will be able to see it in variable
'value', too.


Armin

[bob]

Re: problem with checking null or empty value in detailsview

Thanks for replying ...
I tried this:

Protected Sub DetailsView1_It emInserting(ByV al sender As Object, ByVal e As
System.Web.UI.W ebControls.Deta ilsViewInsertEv entArgs) Handles
DetailsView1.It emInserting
Dim h As Object
h = e.Values("myfie ld")
If h Is DBNull.Value Then
e.Cancel = True
Label1.Text = "may not be empty."
End If
End Sub

But now, the event is never cancelled and every value is accepted. In the
db, i see NULL when rhe input in the textbox was empty.
I conclude that 'h' is not DBNULL , but how to cancel the event when the
input is empty?

Thanks



"Armin Zingler" <az.nospam@free net.deschreef in bericht
news:%23vgcgkur IHA.3456@TK2MSF TNGP05.phx.gbl. ..

"bob" <bob@gh.vbschri eb

>Hi,
>>
>i want to check whether the textbox of the detailsview is not left
>empty, in insert mode.
>I did this:
>>
>Protected Sub DetailsView1_It emInserting(ByV al sender As Object,
>ByVal e As System.Web.UI.W ebControls.Deta ilsViewInsertEv entArgs)
>Handles
>DetailsView1.I temInserting
> Dim h As String
> h = e.Values("myfie ld")
> 'If h = "" Then
> If h Is Nothing Then
> e.Cancel = True
> Label1.Text = "may not be empty."
> End If
> End Sub
>>
>I tried two ways (with ="" and with is nothing), but in both cases,
>i always get the label text and the event is always cancelled, even
>when i full some value.
>>
>So, what's wrong with this code?

>
First, you should enable Option Strict. The assignment
>
h = e.Values("myfie ld")
>
is not valid.
>
Then, you can examine the return value of e.Values. Maybe it is
DBNull.Value. If it is, you can do the comparison:
>
Dim Value as object
value = e.Values("myfie ld")
>
if value is dbnull.value then
'...
end if
>
If it's any other value, you will be able to see it in variable 'value',
too.
>
>
Armin

[Armin Zingler]

Re: problem with checking null or empty value in detailsview

"bob" <bob@gh.vbschri eb

Thanks for replying ...
I tried this:
>
Protected Sub DetailsView1_It emInserting(ByV al sender As Object,
ByVal e As System.Web.UI.W ebControls.Deta ilsViewInsertEv entArgs)
Handles
DetailsView1.It emInserting
Dim h As Object
h = e.Values("myfie ld")
If h Is DBNull.Value Then
e.Cancel = True
Label1.Text = "may not be empty."
End If
End Sub
>
But now, the event is never cancelled and every value is accepted.
In the db, i see NULL when rhe input in the textbox was empty.
I conclude that 'h' is not DBNULL , but how to cancel the event when
the input is empty?

Use the built-in debugging features. Have you tried logging to debug
output? For example

Debug.Print(h.G etType.ToString )


Armin