Returning Nothing from Function

**sloan** · Jun 27 '08, 08:01 PM

Re: Returning Nothing from Function

You can try this.

Public Shared Function GetDateTime(ByV al DateValue As String) As String

dim returnValue as DateTime = DateTime.MinVal ue

If Not String.IsNullOr Empty(DateValue ) Then
DateTime.TryPar se(DateValue, out returnValue ) ''Check Syntax
here, but it should be right..I'm primarily c# now

End If

if ( returnValue = DateTime.MinVal ue ) then
return Nothing
end if

return returnValue

End Function

Or research "nullable".

"James" <James@discussi ons.microsoft.c omwrote in message
news:8192FA1E-C2C8-4845-9E3F-516F9A5ED65A@mi crosoft.com...

Hello,
>
I am trying to create a Function to test TextBoxes and convert the Text to
DateTime if not empty.
>
My code is :
>
Public Shared Function GetDateTime(ByV al DateValue As String) As String
>
If Not String.IsNullOr Empty(DateValue ) Then
Return DateTime.Parse( DateValue)
Else
Return Nothing
End If
>
End Function
>
Then in a OnClick command I have:
>
CurrentMember.S tartDate = GetDateTime(txt StartDate.Text)
>
It works ok when there is a date but if its empty I get an error message:
System.InvalidC astException: Conversion from string "" to type 'Date' is
not
valid.
>
If I do CurrentMember.S tartDate = Nothing it works fine so no problem with
Null values in the field.
>
Does anyone have any suggestions as this has puzzled me for too long now.
>
Thanks in advance
James

**ThatsIT.net.au** · Jun 27 '08, 08:01 PM

Re: Returning Nothing from Function

"James" <James@discussi ons.microsoft.c omwrote in message
news:8192FA1E-C2C8-4845-9E3F-516F9A5ED65A@mi crosoft.com...

Hello,
>
I am trying to create a Function to test TextBoxes and convert the Text to
DateTime if not empty.
>
My code is :
>
Public Shared Function GetDateTime(ByV al DateValue As String) As String
>
If Not String.IsNullOr Empty(DateValue ) Then
Return DateTime.Parse( DateValue)
Else
Return Nothing
End If
>
End Function
>
Then in a OnClick command I have:
>
CurrentMember.S tartDate = GetDateTime(txt StartDate.Text)
>
It works ok when there is a date but if its empty I get an error message:
System.InvalidC astException: Conversion from string "" to type 'Date' is
not
valid.
>
If I do CurrentMember.S tartDate = Nothing it works fine so no problem with
Null values in the field.
>
Does anyone have any suggestions as this has puzzled me for too long now.
>
Thanks in advance
James

If Not String.IsNullOr Empty(DateValue ) AND DateValue <String.Empty Then

**ThatsIT.net.au** · Jun 27 '08, 08:01 PM

Re: Returning Nothing from Function

"James" <James@discussi ons.microsoft.c omwrote in message
news:8192FA1E-C2C8-4845-9E3F-516F9A5ED65A@mi crosoft.com...

Hello,
>
I am trying to create a Function to test TextBoxes and convert the Text to
DateTime if not empty.
>
My code is :
>
Public Shared Function GetDateTime(ByV al DateValue As String) As String
>
If Not String.IsNullOr Empty(DateValue ) Then
Return DateTime.Parse( DateValue)
Else
Return Nothing
End If
>
End Function
>
Then in a OnClick command I have:
>
CurrentMember.S tartDate = GetDateTime(txt StartDate.Text)
>
It works ok when there is a date but if its empty I get an error message:
System.InvalidC astException: Conversion from string "" to type 'Date' is
not
valid.
>
If I do CurrentMember.S tartDate = Nothing it works fine so no problem with
Null values in the field.
>
Does anyone have any suggestions as this has puzzled me for too long now.
>
Thanks in advance
James

sorry misread your post

Function GetDateTime(ByV al DateValue As String) As String
Try
Return DateTime.Parse( DateValue)
Catch ex As Exception
Return Nothing
End Try
End Function

**sloan** · Jun 27 '08, 08:01 PM

Re: Returning Nothing from Function

You should not use Exception catching as a part of normal business flow.

Krzysztof Cwalina

http://blogs.msdn.com/kcwalina/archive/2005/03/16/396787.aspx

I would stick with my TryParse version before I'd use the catch exception
version.

...

"ThatsIT.net.au " <me@workwrote in message
news:784FB9FB-E666-405A-A94F-DCC29935AA91@mi crosoft.com...

>
"James" <James@discussi ons.microsoft.c omwrote in message
news:8192FA1E-C2C8-4845-9E3F-516F9A5ED65A@mi crosoft.com...

>Hello,
>>
>I am trying to create a Function to test TextBoxes and convert the Text
>to
>DateTime if not empty.
>>
>My code is :
>>
>Public Shared Function GetDateTime(ByV al DateValue As String) As String
>>
> If Not String.IsNullOr Empty(DateValue ) Then
> Return DateTime.Parse( DateValue)
> Else
> Return Nothing
> End If
>>
> End Function
>>
>Then in a OnClick command I have:
>>
>CurrentMember. StartDate = GetDateTime(txt StartDate.Text)
>>
>It works ok when there is a date but if its empty I get an error message:
>System.Invalid CastException: Conversion from string "" to type 'Date' is
>not
>valid.
>>
>If I do CurrentMember.S tartDate = Nothing it works fine so no problem
>with
>Null values in the field.
>>
>Does anyone have any suggestions as this has puzzled me for too long now.
>>
>Thanks in advance
>James

>
sorry misread your post
>
Function GetDateTime(ByV al DateValue As String) As String
Try
Return DateTime.Parse( DateValue)
Catch ex As Exception
Return Nothing
End Try
End Function
>

**wisccal@googlemail.com** · Jun 27 '08, 08:01 PM

Re: Returning Nothing from Function

Hi James,

Apparently, VB.Net converts Nothing to "". Therefore, I suggest you
declare your method to return a DateTime value as opposed to a string.
Nothing will then be converted into DateTime.MinVal ue (01/01/0001) as
you probably already noticed when you assigned Nothing directly to
CurrentMember.S tartDate.

But to safeguard against strings that are invalid dates, I would also
incorporate Try/Catch or TryParse as recommended by the previous
posters.

==========
Regards,
Steve

https://www.stkomp.com

On Apr 19, 9:15 am, James <Ja...@discussi ons.microsoft.c omwrote:

Hello,
>
I am trying to create a Function to test TextBoxes and convert the Text to
DateTime if not empty.
>
My code is :
>
Public Shared Function GetDateTime(ByV al DateValue As String) As String
>
If Not String.IsNullOr Empty(DateValue ) Then
Return DateTime.Parse( DateValue)
Else
Return Nothing
End If
>
End Function
>
Then in a OnClick command I have:
>
CurrentMember.S tartDate = GetDateTime(txt StartDate.Text)
>
It works ok when there is a date but if its empty I get an error message:
System.InvalidC astException: Conversion from string "" to type 'Date' is not
valid.
>
If I do CurrentMember.S tartDate = Nothing it works fine so no problem with
Null values in the field.
>
Does anyone have any suggestions as this has puzzled me for too long now.
>
Thanks in advance
James

**Cowboy \(Gregory A. Beamer\)** · Jun 27 '08, 08:01 PM

Re: Returning Nothing from Function

You can use nullable types, if using 2.0, but you will have to test the
value before you bind it, as Nothing/null blows up when bound to a control.

As far as conversion, .TryParse() is a safer method of setting a DateTime,
as users sometimes do not respect dates.

If you want to force dates, you can make the control so it cannot be filled
in and use a calendar control. Or you can use an AJAX masked edit (in the
AJAX control toolkit).

--
Gregory A. Beamer
MVP, MCP: +I, SE, SD, DBA

Subscribe to my blog

http://gregorybeamer.spaces.live.com/lists/feed.rss

or just read it:

http://gregorybeamer.spaces.live.com/

*************** *************** *************** ****
| Think outside the box!
|
*************** *************** *************** ****
"James" <James@discussi ons.microsoft.c omwrote in message
news:8192FA1E-C2C8-4845-9E3F-516F9A5ED65A@mi crosoft.com...

Hello,
>
I am trying to create a Function to test TextBoxes and convert the Text to
DateTime if not empty.
>
My code is :
>
Public Shared Function GetDateTime(ByV al DateValue As String) As String
>
If Not String.IsNullOr Empty(DateValue ) Then
Return DateTime.Parse( DateValue)
Else
Return Nothing
End If
>
End Function
>
Then in a OnClick command I have:
>
CurrentMember.S tartDate = GetDateTime(txt StartDate.Text)
>
It works ok when there is a date but if its empty I get an error message:
System.InvalidC astException: Conversion from string "" to type 'Date' is
not
valid.
>
If I do CurrentMember.S tartDate = Nothing it works fine so no problem with
Null values in the field.
>
Does anyone have any suggestions as this has puzzled me for too long now.
>
Thanks in advance
James

**ThatsIT.net.au** · Jun 27 '08, 08:01 PM

Re: Returning Nothing from Function

"sloan" <sloan@ipass.ne twrote in message
news:uUu6CdkoIH A.1164@TK2MSFTN GP04.phx.gbl...

>
You should not use Exception catching as a part of normal business flow.

thats a opinion only, I do not agree with it.

>
>

Krzysztof Cwalina

http://blogs.msdn.com/kcwalina/archive/2005/03/16/396787.aspx

>
>
I would stick with my TryParse version before I'd use the catch exception
version.
>
>
..
>
>
>
>
>
"ThatsIT.net.au " <me@workwrote in message
news:784FB9FB-E666-405A-A94F-DCC29935AA91@mi crosoft.com...

>>
>"James" <James@discussi ons.microsoft.c omwrote in message
>news:8192FA1 E-C2C8-4845-9E3F-516F9A5ED65A@mi crosoft.com...

>>Hello,
>>>
>>I am trying to create a Function to test TextBoxes and convert the Text
>>to
>>DateTime if not empty.
>>>
>>My code is :
>>>
>>Public Shared Function GetDateTime(ByV al DateValue As String) As String
>>>
>> If Not String.IsNullOr Empty(DateValue ) Then
>> Return DateTime.Parse( DateValue)
>> Else
>> Return Nothing
>> End If
>>>
>> End Function
>>>
>>Then in a OnClick command I have:
>>>
>>CurrentMember .StartDate = GetDateTime(txt StartDate.Text)
>>>
>>It works ok when there is a date but if its empty I get an error
>>message:
>>System.Invali dCastException: Conversion from string "" to type 'Date' is
>>not
>>valid.
>>>
>>If I do CurrentMember.S tartDate = Nothing it works fine so no problem
>>with
>>Null values in the field.
>>>
>>Does anyone have any suggestions as this has puzzled me for too long
>>now.
>>>
>>Thanks in advance
>>James

>>
>sorry misread your post
>>
>Function GetDateTime(ByV al DateValue As String) As String
> Try
> Return DateTime.Parse( DateValue)
> Catch ex As Exception
> Return Nothing
> End Try
> End Function
>>

>
>

**Mark Rae [MVP]** · Jun 27 '08, 08:02 PM

Re: Returning Nothing from Function

"sloan" <sloan@ipass.ne twrote in message
news:uUu6CdkoIH A.1164@TK2MSFTN GP04.phx.gbl...

You should not use Exception catching as a part of normal business flow.
http://blogs.msdn.com/kcwalina/archi...16/396787.aspx

Agreed 100%.

--
Mark Rae
ASP.NET MVP

Mark Rae - JavaScript Disabled

http://www.markrae.net

**ThatsIT.net.au** · Jun 27 '08, 08:02 PM

Re: Returning Nothing from Function

"Mark Rae [MVP]" <mark@markNOSPA Mrae.netwrote in message
news:%23%238Kqz voIHA.4716@TK2M SFTNGP06.phx.gb l...

"sloan" <sloan@ipass.ne twrote in message
news:uUu6CdkoIH A.1164@TK2MSFTN GP04.phx.gbl...
>

>You should not use Exception catching as a part of normal business flow.
>http://blogs.msdn.com/kcwalina/archi...16/396787.aspx

>
Agreed 100%.
>
>

Technet is full of examples of doing just that

SqlCommand Class (System.Data.SqlClient)

http://msdn2.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand(VS.71).aspx

Represents a Transact-SQL statement or stored procedure to execute against a SQL Server database. This class cannot be inherited.

--
Mark Rae
ASP.NET MVP
http://www.markrae.net

**sloan** · Jun 27 '08, 08:02 PM

Re: Returning Nothing from Function

SqlCommand Class (System.Data.SqlClient)

http://msdn2.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand(VS.71).aspx

Represents a Transact-SQL statement or stored procedure to execute against a SQL Server database. This class cannot be inherited.

That's a try/finally block, not a try/catch or a try/catch/finally block.

Yes, you're' right, technet is full of try/finally examples.
But we aren't discussing try/finally blocks, we're discussing try/catch
blocks.

...

//thats a opinion only, I do not agree with it.//
Since Brad Abrams and Krzysztof Cwalina have probably forgotten more about
..Net then most people know (including myself), I'd probably value their
opinion more highly.

Exception Handling

http://msdn2.microsoft.com/en-us/library/ms229005.aspx

Exceptions and Performance - Framework Design Guidelines

http://msdn2.microsoft.com/en-us/library/ms229009.aspx

Learn more about: Exceptions and Performance

"ThatsIT.net.au " <me@workwrote in message
news:0502FA77-0E67-441D-A328-F818D8A50B9C@mi crosoft.com...

"Mark Rae [MVP]" <mark@markNOSPA Mrae.netwrote in message
news:%23%238Kqz voIHA.4716@TK2M SFTNGP06.phx.gb l...

>"sloan" <sloan@ipass.ne twrote in message
>news:uUu6CdkoI HA.1164@TK2MSFT NGP04.phx.gbl.. .
>>

>>You should not use Exception catching as a part of normal business flow.
>>http://blogs.msdn.com/kcwalina/archi...16/396787.aspx

>>
>Agreed 100%.
>>
>>

>
Technet is full of examples of doing just that
>

SqlCommand Class (System.Data.SqlClient)