?
Solved

Validation problems when users blank out a textbox bound to a number field in vb.net windows app.

Posted on 2008-09-30
6
Medium Priority
?
323 Views
Last Modified: 2013-11-26
In my VS 2008 vb.net project I have some textboxes bound to number fields in the DB. when the user enters a number, then blanks out the number and moves off the textbox and tries to save the record it fails because it trys to save an empty string in the record.
How can I best handle this?

thanks,
bmutch
0
Comment
Question by:PACCAST-DEV
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
6 Comments
 
LVL 53

Accepted Solution

by:
Dhaest earned 1500 total points
ID: 22612002
What you need is to hook the Parse event and in the event handler check the
argument value. If it is a string and empty, set the value to System.DBNull.Value.

Binding aBinding = new Binding("Text", your_datasource,"your field name");
aBinding .Parse +=new ConvertEventHandler(Parse_Handler);


Source: http://www.sitepoint.com/forums/showthread.php?t=289691
Private Sub Parse_Handler(sender As Object, e As ConvertEventArgs) 
    If e.Value.[GetType]() = Type.[GetType]("System.String") Then 
        Dim s As String = DirectCast(e.Value, String) 
        If s.Trim().Length <= 0 Then 
            e.Value = System.DBNull.Value 
        End If 
    End If 
End Sub 

Open in new window

0
 
LVL 101

Expert Comment

by:mlmcc
ID: 22614594
That is one method if you want NULLs in the field.

Generally I handle this through the LostFocus event.  I check if the value is valid and if not don't let them leave the textbox until they put a valid value in it.

mlmcc
0
 

Author Comment

by:PACCAST-DEV
ID: 22615062
Yes, I do allow nulls in these number fields.
Dhaest: - I have to declare this binding variable for every (about 10) field I want to take care of in this manner?
0
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

 

Author Comment

by:PACCAST-DEV
ID: 22615148
where does this line go:
aBinding .Parse +=new ConvertEventHandler(Parse_Handler);
 and this line gives error:
If e.Value.[GetType]() = Type.[GetType]("System.String") Then
error : operator = is not defined for types system.type...
0
 

Author Comment

by:PACCAST-DEV
ID: 22616983
looks like I got it working, lot of hassle to just take care of the empty textbox...
0
 

Author Comment

by:PACCAST-DEV
ID: 22638715
I used a variation of the "Binding" method above. Am dissappointed that this is so hard to do in VS...
0

Featured Post

Cloud Training Guides

FREE GUIDES: In-depth and hand-crafted Linux, AWS, OpenStack, DevOps, Azure, and Cloud training guides created by Linux Academy instructors and the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Many of us here at EE write code. Many of us write exceptional code; just as many of us write exception-prone code. As we all should know, exceptions are a mechanism for handling errors which are typically out of our control. From database errors, t…
For those of you who don't follow the news, or just happen to live under rocks, Microsoft Research released a beta SDK (http://www.microsoft.com/en-us/download/details.aspx?id=27876) for the Xbox 360 Kinect. If you don't know what a Kinect is (http:…
In this video, Percona Solution Engineer Dimitri Vanoverbeke discusses why you want to use at least three nodes in a database cluster. To discuss how Percona Consulting can help with your design and architecture needs for your database and infras…
How to fix incompatible JVM issue while installing Eclipse While installing Eclipse in windows, got one error like above and unable to proceed with the installation. This video describes how to successfully install Eclipse. How to solve incompa…
Suggested Courses

771 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question