Returning Nothing from Function

[=?Utf-8?B?SmFtZXM=?=]

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(ByVal DateValue As String) As String

If Not String.IsNullOrEmpty(DateValue) Then
Return DateTime.Parse(DateValue)
Else
Return Nothing
End If

End Function

Then in a OnClick command I have:

CurrentMember.StartDate = GetDateTime(txtStartDate.Text)

It works ok when there is a date but if its empty I get an error message:
System.InvalidCastException: Conversion from string "" to type 'Date' is not
valid.

If I do CurrentMember.StartDate = 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

[sloan]

You can try this.
Public Shared Function GetDateTime(ByVal DateValue As String) As String

dim returnValue as DateTime = DateTime.MinValue

If Not String.IsNullOrEmpty(DateValue) Then
DateTime.TryParse(DateValue, out returnValue ) ''Check Syntax
here, but it should be right..I'm primarily c# now
End If
if ( returnValue = DateTime.MinValue ) then
return Nothing
end if

return returnValue
End Function
Or research "nullable".

"James" <Ja***@discussions.microsoft.comwrote in message
news:81**********************************@microsof t.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(ByVal DateValue As String) As String

If Not String.IsNullOrEmpty(DateValue) Then
Return DateTime.Parse(DateValue)
Else
Return Nothing
End If

End Function

Then in a OnClick command I have:

CurrentMember.StartDate = GetDateTime(txtStartDate.Text)

It works ok when there is a date but if its empty I get an error message:
System.InvalidCastException: Conversion from string "" to type 'Date' is
not
valid.

If I do CurrentMember.StartDate = 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]

"James" <Ja***@discussions.microsoft.comwrote in message
news:81**********************************@microsof t.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(ByVal DateValue As String) As String

If Not String.IsNullOrEmpty(DateValue) Then
Return DateTime.Parse(DateValue)
Else
Return Nothing
End If

End Function

Then in a OnClick command I have:

CurrentMember.StartDate = GetDateTime(txtStartDate.Text)

It works ok when there is a date but if its empty I get an error message:
System.InvalidCastException: Conversion from string "" to type 'Date' is
not
valid.

If I do CurrentMember.StartDate = 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.IsNullOrEmpty(DateValue) AND DateValue <String.Empty Then

[ThatsIT.net.au]

"James" <Ja***@discussions.microsoft.comwrote in message
news:81**********************************@microsof t.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(ByVal DateValue As String) As String

If Not String.IsNullOrEmpty(DateValue) Then
Return DateTime.Parse(DateValue)
Else
Return Nothing
End If

End Function

Then in a OnClick command I have:

CurrentMember.StartDate = GetDateTime(txtStartDate.Text)

It works ok when there is a date but if its empty I get an error message:
System.InvalidCastException: Conversion from string "" to type 'Date' is
not
valid.

If I do CurrentMember.StartDate = 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(ByVal DateValue As String) As String
Try
Return DateTime.Parse(DateValue)
Catch ex As Exception
Return Nothing
End Try
End Function

[sloan]

You should not use Exception catching as a part of normal business flow.
http://blogs.msdn.com/kcwalina/archi...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:78**********************************@microsof t.com...

>
"James" <Ja***@discussions.microsoft.comwrote in message
news:81**********************************@microsof t.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(ByVal DateValue As String) As String

If Not String.IsNullOrEmpty(DateValue) Then
Return DateTime.Parse(DateValue)
Else
Return Nothing
End If

End Function

Then in a OnClick command I have:

CurrentMember.StartDate = GetDateTime(txtStartDate.Text)

It works ok when there is a date but if its empty I get an error message:
System.InvalidCastException: Conversion from string "" to type 'Date' is
not
valid.

If I do CurrentMember.StartDate = 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(ByVal DateValue As String) As String
Try
Return DateTime.Parse(DateValue)
Catch ex As Exception
Return Nothing
End Try
End Function

[wisccal]

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.MinValue (01/01/0001) as
you probably already noticed when you assigned Nothing directly to
CurrentMember.StartDate.

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
www.stkomp.com

On Apr 19, 9:15 am, James <[e-mail]:

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(ByVal DateValue As String) As String

If Not String.IsNullOrEmpty(DateValue) Then
Return DateTime.Parse(DateValue)
Else
Return Nothing
End If

End Function

Then in a OnClick command I have:

CurrentMember.StartDate = GetDateTime(txtStartDate.Text)

It works ok when there is a date but if its empty I get an error message:
System.InvalidCastException: Conversion from string "" to type 'Date' is not
valid.

If I do CurrentMember.StartDate = 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 \(Gregory A. Beamer\)]

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" <Ja***@discussions.microsoft.comwrote in message
news:81**********************************@microsof t.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(ByVal DateValue As String) As String

If Not String.IsNullOrEmpty(DateValue) Then
Return DateTime.Parse(DateValue)
Else
Return Nothing
End If

End Function

Then in a OnClick command I have:

CurrentMember.StartDate = GetDateTime(txtStartDate.Text)

It works ok when there is a date but if its empty I get an error message:
System.InvalidCastException: Conversion from string "" to type 'Date' is
not
valid.

If I do CurrentMember.StartDate = 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]

"sloan" <sl***@ipass.netwrote in message
news:uU**************@TK2MSFTNGP04.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.

>

http://blogs.msdn.com/kcwalina/archi...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:78**********************************@microsof t.com...

>>
"James" <Ja***@discussions.microsoft.comwrote in message
news:81**********************************@microso ft.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(ByVal DateValue As String) As String

If Not String.IsNullOrEmpty(DateValue) Then
Return DateTime.Parse(DateValue)
Else
Return Nothing
End If

End Function

Then in a OnClick command I have:

CurrentMember.StartDate = GetDateTime(txtStartDate.Text)

It works ok when there is a date but if its empty I get an error
message:
System.InvalidCastException: Conversion from string "" to type 'Date' is
not
valid.

If I do CurrentMember.StartDate = 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(ByVal DateValue As String) As String
Try
Return DateTime.Parse(DateValue)
Catch ex As Exception
Return Nothing
End Try
End Function

[Mark Rae [MVP]]

"sloan" <sl***@ipass.netwrote in message
news:uU**************@TK2MSFTNGP04.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
http://www.markrae.net

[ThatsIT.net.au]

"Mark Rae [MVP]" <ma**@markNOSPAMrae.netwrote in message
news:%2******************@TK2MSFTNGP06.phx.gbl...

"sloan" <sl***@ipass.netwrote in message
news:uU**************@TK2MSFTNGP04.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

http://msdn2.microsoft.com/en-us/lib...nd(VS.71).aspx

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

[sloan]

http://msdn2.microsoft.com/en-us/lib...nd(VS.71).aspx
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.


http://msdn2.microsoft.com/en-us/library/ms229005.aspx
http://msdn2.microsoft.com/en-us/library/ms229009.aspx



"ThatsIT.net.au" <me@workwrote in message
news:05**********************************@microsof t.com...

"Mark Rae [MVP]" <ma**@markNOSPAMrae.netwrote in message
news:%2******************@TK2MSFTNGP06.phx.gbl...

>"sloan" <sl***@ipass.netwrote in message
news:uU**************@TK2MSFTNGP04.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

http://msdn2.microsoft.com/en-us/lib...nd(VS.71).aspx

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