Check blank text box using custom validator

[Alex Shirley]

Hi there

I’m simply trying to check for a blank or empty value in a textbox on my
webform. In this instance I do not want to use a requiredfieldva lidator,
I want to use a customvalidator (as I have other code within the
customvalidator which works).

This won’t work (within servervalidate) :

If txtBox.Text.ToS tring = "" Then raise exception…..

Nor will this

If txtBox.Text = "" Then raise exception…

I’ve tried null (perhaps I didn’t do that correctly) but is doesn’t seem
to work either, any ideas?

Seems a really simple thing to do (but /sigh! I just can't do it).

Thanks

Alex

*** Sent via Developersdex http://www.developersdex.com ***
Don't just participate in USENET...get rewarded for it!

[Teemu Keiski]

Re: Check blank text box using custom validator

Hi,

show bit more the code you have. Are you sure the txtBox refers correctly to
the TextBox?

If you need more background info about ASp.NET validation (also custom
validators) see this article:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnaspp/html/aspplusvalid.asp

--
Teemu Keiski
MCP, Microsoft MVP (ASP.NET), AspInsiders member
ASP.NET Forum Moderator, AspAlliance Columnist

http://blogs.aspadvice.com/joteke

"Alex Shirley" <postings@alexs hirley.com> wrote in message
news:OU$91hlaEH A.1356@TK2MSFTN GP09.phx.gbl...[color=blue]
> Hi there
>
> I'm simply trying to check for a blank or empty value in a textbox on my
> webform. In this instance I do not want to use a requiredfieldva lidator,
> I want to use a customvalidator (as I have other code within the
> customvalidator which works).
>
> This won't work (within servervalidate) :
>
> If txtBox.Text.ToS tring = "" Then raise exception...
>
> Nor will this
>
> If txtBox.Text = "" Then raise exception.
>
> I've tried null (perhaps I didn't do that correctly) but is doesn't seem
> to work either, any ideas?
>
> Seems a really simple thing to do (but /sigh! I just can't do it).
>
> Thanks
>
> Alex
>
> *** Sent via Developersdex http://www.developersdex.com ***
> Don't just participate in USENET...get rewarded for it![/color]

[Mike Smith]

Re: Check blank text box using custom validator

u raising an exception ?
with the customvalidator , as long as u link the controltovalida te property
u just need to code the login of when the condition is valid.. the
serverValidate event has an args parameter,, u need to set it to either true
or false/

If txtBox.Text.ToS tring="" then
args.IsValid=fa lse
else
args.IsValid=tr ue
end if

u can add the same in a client side script also and link the
clientvalidatio n function property...

"Alex Shirley" <postings@alexs hirley.com> wrote in message
news:OU$91hlaEH A.1356@TK2MSFTN GP09.phx.gbl...[color=blue]
> Hi there
>
> I'm simply trying to check for a blank or empty value in a textbox on my
> webform. In this instance I do not want to use a requiredfieldva lidator,
> I want to use a customvalidator (as I have other code within the
> customvalidator which works).
>
> This won't work (within servervalidate) :
>
> If txtBox.Text.ToS tring = "" Then raise exception...
>
> Nor will this
>
> If txtBox.Text = "" Then raise exception.
>
> I've tried null (perhaps I didn't do that correctly) but is doesn't seem
> to work either, any ideas?
>
> Seems a really simple thing to do (but /sigh! I just can't do it).
>
> Thanks
>
> Alex
>
> *** Sent via Developersdex http://www.developersdex.com ***
> Don't just participate in USENET...get rewarded for it![/color]


---
Outgoing mail is certified Virus Free. (well i'd like to think it is.. )
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.720 / Virus Database: 476 - Release Date: 14/07/2004

[DujHoD]

Re: Check blank text box using custom validator

For a CustomValidator , you don't want to raise an exception; you want
to modify the ServerValidateE ventArgs that's passed in, like this:

Sub ValidateTextBox (sender as Object, args as
ServerValidateE ventArgs)
Dim valid As Boolean
valid = (txtBox.Text.Le ngth > 0)
' Do other stuff here...
args.IsValid = valid
End Sub

Instead of txtBox.Text, you could also use args.Value, which would
arguably make your code more maintainable:

valid = (args.Value.Len gth > 0)

Clent-side validation works in much the same way. Is this what you're
asking about?


Alex Shirley <postings@alexs hirley.com> wrote in message news:<OU$91hlaE HA.1356@TK2MSFT NGP09.phx.gbl>. ..[color=blue]
> Hi there
>
> I?m simply trying to check for a blank or empty value in a textbox on my
> webform. In this instance I do not want to use a requiredfieldva lidator,
> I want to use a customvalidator (as I have other code within the
> customvalidator which works).
>
> This won?t work (within servervalidate) :
>
> If txtBox.Text.ToS tring = "" Then raise exception?..
>
> Nor will this
>
> If txtBox.Text = "" Then raise exception?
>
> I?ve tried null (perhaps I didn?t do that correctly) but is doesn?t seem
> to work either, any ideas?
>
> Seems a really simple thing to do (but /sigh! I just can't do it).[/color]

[Alex Shirley]

Re: Check blank text box using custom validator

Thank for this

My initial impressions from your posts are that I'm doing everything
right (which is probably flawed!).

I think I'd better look at this tomorrow under a fresh perspective and
will provide some feedback.

Thanks

Alex


*** Sent via Developersdex http://www.developersdex.com ***
Don't just participate in USENET...get rewarded for it!

[Alex Shirley]

Re: Check blank text box using custom validator

Weird, any ideas with this ....?

-----------------------------------------------------------
This code works
-----------------------------------------------------------

'If user types hello, the custom validator flags up
Private Sub cvProductStartD ate_ServerValid ate(ByVal source As
System.Object, ByVal args As
System.Web.UI.W ebControls.Serv erValidateEvent Args) Handles
cvProductStartD ate.ServerValid ate

If txtProductStart Date.Text.ToStr ing <> "hello" Then
args.IsValid = True
Else
cvProductStartD ate.ErrorMessag e = "You typed hello"
args.IsValid = False
End If
End Sub

-----------------------------------------------------------
This code doesn't work
-----------------------------------------------------------

'Checks for a blank textbox, does not work!
Private Sub cvProductStartD ate_ServerValid ate(ByVal source As
System.Object, ByVal args As
System.Web.UI.W ebControls.Serv erValidateEvent Args) Handles
cvProductStartD ate.ServerValid ate

If txtProductStart Date.Text.ToStr ing <> "" Then
args.IsValid = True
Else
cvProductStartD ate.ErrorMessag e = "Type something in"
args.IsValid = False
End If
End Sub
---------------------------------------------------------

Cheers!

Alex


*** Sent via Developersdex http://www.developersdex.com ***
Don't just participate in USENET...get rewarded for it!

[Mike Smith]

Re: Check blank text box using custom validator

well i guess thats the idea why they made the requiredfield validator ?
cause thats the only control that checks that.. and u suppose to use the
various validation controls in conjuction with each other.. so place a
required validator to check for blanks and then ur custom one with what ever
logic u need to check...

i guess thats why in the books they say the required field validator is THE
ONLY validator that can check for blanks ? well thats the line ive read
someplace...

"Alex Shirley" <postings@alexs hirley.com> wrote in message
news:up6GdSyaEH A.3016@tk2msftn gp13.phx.gbl...[color=blue]
> Weird, any ideas with this ....?
>
> -----------------------------------------------------------
> This code works
> -----------------------------------------------------------
>
> 'If user types hello, the custom validator flags up
> Private Sub cvProductStartD ate_ServerValid ate(ByVal source As
> System.Object, ByVal args As
> System.Web.UI.W ebControls.Serv erValidateEvent Args) Handles
> cvProductStartD ate.ServerValid ate
>
> If txtProductStart Date.Text.ToStr ing <> "hello" Then
> args.IsValid = True
> Else
> cvProductStartD ate.ErrorMessag e = "You typed hello"
> args.IsValid = False
> End If
> End Sub
>
> -----------------------------------------------------------
> This code doesn't work
> -----------------------------------------------------------
>
> 'Checks for a blank textbox, does not work!
> Private Sub cvProductStartD ate_ServerValid ate(ByVal source As
> System.Object, ByVal args As
> System.Web.UI.W ebControls.Serv erValidateEvent Args) Handles
> cvProductStartD ate.ServerValid ate
>
> If txtProductStart Date.Text.ToStr ing <> "" Then
> args.IsValid = True
> Else
> cvProductStartD ate.ErrorMessag e = "Type something in"
> args.IsValid = False
> End If
> End Sub
> ---------------------------------------------------------
>
> Cheers!
>
> Alex
>
>
> *** Sent via Developersdex http://www.developersdex.com ***
> Don't just participate in USENET...get rewarded for it![/color]


---
Outgoing mail is certified Virus Free. (well i'd like to think it is.. )
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.720 / Virus Database: 476 - Release Date: 14/07/2004

[Teemu Keiski]

Re: Check blank text box using custom validator

Hi,

just to add that if you use CustomValidator but don't specify the
ControlToValida te property it will fire the validation despite if control is
empty or not (because the control is not specified, it runs the validation
always and therefore you could validate empty controls as well with it).

See this article:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnaspp/html/aspplusvalid.asp

The behaviour is described there:
"You can leave the ControlToValida te blank. In this mode, the server
function always fires once per round trip and the client function always
fires once for each attempt to submit. You can use this to validate controls
that cannot otherwise be validated, such as a CheckBoxList or stand-alone
radio buttons. It can also be useful when the condition is based on multiple
controls and you don't want it evaluated as the user tabs between fields on
the page"

But the result is that you can also use it for blank controls...

--
Teemu Keiski
MCP, Microsoft MVP (ASP.NET), AspInsiders member
ASP.NET Forum Moderator, AspAlliance Columnist

http://blogs.aspadvice.com/joteke

"Mike Smith" <test@test.co m> wrote in message
news:%23DKibXAb EHA.3692@TK2MSF TNGP09.phx.gbl. ..[color=blue]
> well i guess thats the idea why they made the requiredfield validator ?
> cause thats the only control that checks that.. and u suppose to use the
> various validation controls in conjuction with each other.. so place a
> required validator to check for blanks and then ur custom one with what[/color]
ever[color=blue]
> logic u need to check...
>
> i guess thats why in the books they say the required field validator is[/color]
THE[color=blue]
> ONLY validator that can check for blanks ? well thats the line ive read
> someplace...
>
> "Alex Shirley" <postings@alexs hirley.com> wrote in message
> news:up6GdSyaEH A.3016@tk2msftn gp13.phx.gbl...[color=green]
> > Weird, any ideas with this ....?
> >
> > -----------------------------------------------------------
> > This code works
> > -----------------------------------------------------------
> >
> > 'If user types hello, the custom validator flags up
> > Private Sub cvProductStartD ate_ServerValid ate(ByVal source As
> > System.Object, ByVal args As
> > System.Web.UI.W ebControls.Serv erValidateEvent Args) Handles
> > cvProductStartD ate.ServerValid ate
> >
> > If txtProductStart Date.Text.ToStr ing <> "hello" Then
> > args.IsValid = True
> > Else
> > cvProductStartD ate.ErrorMessag e = "You typed hello"
> > args.IsValid = False
> > End If
> > End Sub
> >
> > -----------------------------------------------------------
> > This code doesn't work
> > -----------------------------------------------------------
> >
> > 'Checks for a blank textbox, does not work!
> > Private Sub cvProductStartD ate_ServerValid ate(ByVal source As
> > System.Object, ByVal args As
> > System.Web.UI.W ebControls.Serv erValidateEvent Args) Handles
> > cvProductStartD ate.ServerValid ate
> >
> > If txtProductStart Date.Text.ToStr ing <> "" Then
> > args.IsValid = True
> > Else
> > cvProductStartD ate.ErrorMessag e = "Type something in"
> > args.IsValid = False
> > End If
> > End Sub
> > ---------------------------------------------------------
> >
> > Cheers!
> >
> > Alex
> >
> >
> > *** Sent via Developersdex http://www.developersdex.com ***
> > Don't just participate in USENET...get rewarded for it![/color]
>
>
> ---
> Outgoing mail is certified Virus Free. (well i'd like to think it is.. )
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.720 / Virus Database: 476 - Release Date: 14/07/2004
>
>[/color]

[Mike Smith]

Re: Check blank text box using custom validator

hey teemu !
thats a great tip ! thanks...

"Teemu Keiski" <joteke@aspalli ance.com> wrote in message
news:uVkTkIEbEH A.3512@TK2MSFTN GP12.phx.gbl...[color=blue]
> Hi,
>
> just to add that if you use CustomValidator but don't specify the
> ControlToValida te property it will fire the validation despite if control[/color]
is[color=blue]
> empty or not (because the control is not specified, it runs the validation
> always and therefore you could validate empty controls as well with it).
>
> See this article:
>[/color]
http://msdn.microsoft.com/library/de...pplusvalid.asp[color=blue]
>
> The behaviour is described there:
> "You can leave the ControlToValida te blank. In this mode, the server
> function always fires once per round trip and the client function always
> fires once for each attempt to submit. You can use this to validate[/color]
controls[color=blue]
> that cannot otherwise be validated, such as a CheckBoxList or stand-alone
> radio buttons. It can also be useful when the condition is based on[/color]
multiple[color=blue]
> controls and you don't want it evaluated as the user tabs between fields[/color]
on[color=blue]
> the page"
>
> But the result is that you can also use it for blank controls...
>
> --
> Teemu Keiski
> MCP, Microsoft MVP (ASP.NET), AspInsiders member
> ASP.NET Forum Moderator, AspAlliance Columnist
> http://blogs.aspadvice.com/joteke
>
>
> "Mike Smith" <test@test.co m> wrote in message
> news:%23DKibXAb EHA.3692@TK2MSF TNGP09.phx.gbl. ..[color=green]
> > well i guess thats the idea why they made the requiredfield validator ?
> > cause thats the only control that checks that.. and u suppose to use the
> > various validation controls in conjuction with each other.. so place a
> > required validator to check for blanks and then ur custom one with what[/color]
> ever[color=green]
> > logic u need to check...
> >
> > i guess thats why in the books they say the required field validator is[/color]
> THE[color=green]
> > ONLY validator that can check for blanks ? well thats the line ive read
> > someplace...
> >
> > "Alex Shirley" <postings@alexs hirley.com> wrote in message
> > news:up6GdSyaEH A.3016@tk2msftn gp13.phx.gbl...[color=darkred]
> > > Weird, any ideas with this ....?
> > >
> > > -----------------------------------------------------------
> > > This code works
> > > -----------------------------------------------------------
> > >
> > > 'If user types hello, the custom validator flags up
> > > Private Sub cvProductStartD ate_ServerValid ate(ByVal source As
> > > System.Object, ByVal args As
> > > System.Web.UI.W ebControls.Serv erValidateEvent Args) Handles
> > > cvProductStartD ate.ServerValid ate
> > >
> > > If txtProductStart Date.Text.ToStr ing <> "hello" Then
> > > args.IsValid = True
> > > Else
> > > cvProductStartD ate.ErrorMessag e = "You typed hello"
> > > args.IsValid = False
> > > End If
> > > End Sub
> > >
> > > -----------------------------------------------------------
> > > This code doesn't work
> > > -----------------------------------------------------------
> > >
> > > 'Checks for a blank textbox, does not work!
> > > Private Sub cvProductStartD ate_ServerValid ate(ByVal source As
> > > System.Object, ByVal args As
> > > System.Web.UI.W ebControls.Serv erValidateEvent Args) Handles
> > > cvProductStartD ate.ServerValid ate
> > >
> > > If txtProductStart Date.Text.ToStr ing <> "" Then
> > > args.IsValid = True
> > > Else
> > > cvProductStartD ate.ErrorMessag e = "Type something in"
> > > args.IsValid = False
> > > End If
> > > End Sub
> > > ---------------------------------------------------------
> > >
> > > Cheers!
> > >
> > > Alex
> > >
> > >
> > > *** Sent via Developersdex http://www.developersdex.com ***
> > > Don't just participate in USENET...get rewarded for it![/color]
> >
> >
> > ---
> > Outgoing mail is certified Virus Free. (well i'd like to think it is.. )
> > Checked by AVG anti-virus system (http://www.grisoft.com).
> > Version: 6.0.720 / Virus Database: 476 - Release Date: 14/07/2004
> >
> >[/color]
>
>[/color]


---
Outgoing mail is certified Virus Free. (well i'd like to think it is.. )
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.720 / Virus Database: 476 - Release Date: 14/07/2004

[Alex Shirley]

Re: Check blank text box using custom validator

Thanks for this ...!

Alex

*** Sent via Developersdex http://www.developersdex.com ***
Don't just participate in USENET...get rewarded for it!