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
319 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 500 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 100

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
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 

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

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

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

It’s quite interesting for me as I worked with Excel using vb.net for some time. Here are some topics which I know want to share with others whom this might help. First of all if you are working with Excel then you need to Download the Following …
This article shows how to deploy dynamic backgrounds to computers depending on the aspect ratio of display
The Email Laundry PDF encryption service allows companies to send confidential encrypted  emails to anybody. The PDF document can also contain attachments that are embedded in the encrypted PDF. The password is randomly generated by The Email Laundr…

726 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