I've a DataGridView that has a binding source that's tied to a table sitting on SQL Server .
Upon a user modifying a datagridview cell and tabbing or clicking to another cell, I use the CellEndEdit event to update my DataSource (SQL table).
Private Sub dataGridView1_CellEndEdit(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellEndEdit
'****** UPDATING underlying database when user exits cell
EwosappendixbindingSource.EndEdit()
EwosappendixTableAdapter.Update(PIMUserDBDataSet.ewosappendix)
End Sub
As this works well on occasion a user will get a
"concurrency violation: the updatecommand affected 0 of the expected 1 records“” 1
In the cases where the error was thrown, only one user was in the datagridview making a change. They clicked in a cell, modified it's content, and then clicked out of the cell.
With my understanding of what triggers this error, my first question is, why was the error thrown and how can I catch or prevent the error from happening.
thanks,
Jim
Related
I'm having a very strange problem in a VB application. I have a function written like this:
In the innermost condition, two statements are commented out here. These were found to have no effect on the strange behaviour. This is the minimal example I've found causing trouble.
(Note that the names of objects have been changed in this example.)
Private Sub MyForm_CellValidating(ByVal sender As Object, ByVal e As DataGridViewCellValidatingEventArgs) Handles myDGV.CellValidating
Dim dgv As DataGridView = CType(sender, DataGridView)
Select Case dgv.Columns(e.ColumnIndex).Name
Case "uniqueColumn"
' Validate that the values in our unique column are unique.
For i As Integer = 0 To dgv.RowCount - 1
If i <> e.RowIndex Then
' Here i != j, so compare to the value...
If e.FormattedValue = dgv.Rows(i).Cells(e.ColumnIndex).FormattedValue Then
e.Cancel = True
'dgv.ShowRowErrors = True
'dgv.Rows(e.RowIndex).ErrorText = "Data in the unique column must be unique"
End If
End If
Next 'i
Case Else
' Perform no validation.
End Select
End Sub
What trouble, you ask? For some inexplicable reason, whenever the line
e.Cancel = True
is executed, afterwards, nearly all buttons and form widgets in the entire application, including even the close button in its window bar (what a user would use to exit the application) stop doing whatever they previously did and now call this event handler instead.
In other words, commenting out that line (and doing the validation manually when the form is submitted) fixes the problems. I'd like to know why this happens, though. Some pointers:
Here's a list of which things are not affected:
The minimize and maximize button in the top bar.
All objects in its menu bar.
This handler is private to its form class, it's not referenced anywhere else in the application.
I'm at a loss. Just how? What could possibly cause this?
e.Cancel is for stopping the validation when the input is deemed incorrect. This causes the cell to still have focus as the user is expected to correct whatever they did wrong. The CellValidating event will then be raised again whenever the cell is about to lose focus until your code deems the input to be correct.
You can use the Control.CausesValidation property to control whether a control (for instance a button) should raise validation events when it gains focus.
I am attempting to handle a local DB for a program I am doing, but I ran into this error that I can't get my head around! Whenever I attempt to edit a row in the gridview I get this error..
Screenshots:
https://i.gyazo.com/cc48a33863fada3e70e445620e6e9b2e.mp4
https://gyazo.com/5b184ea8aead4407e1bd2f0dd081b38c
You row has multiple column. Free column is a not null column.
When you add row, initialise the value of checkbox column.
dataGridView1.Rows[2].Cells[3].Value = true;
You need to add one event handler to your data grid and handle the error. Example
add the below code in your form loading event
AddHandler DataGridView1.DataError, AddressOf DataErrorHandler
Replace DataGridView1 with your data grid name and then create the below function and handle your error.
Private Sub DataErrorHandler(ByVal sender As Object, ByVal e As DataGridViewDataErrorEventArgs)
'handle the error or do nothing.
End Sub
I am doing a database validation on the TextBox validating event. I am also using the e.Cancel = True if the data is invalid. The problem is that the validating event is triggered twice ultimately causing the SQL also to run twice, and I don't want that to happen (coz sometime the query is resource intensive).
Steps:
Drag & drop a RadTextBox & a RadLabel to the Form.
For the RadTextBox validating event use the below code.
Run the application, focus the RadTextBox & then click on the label. Then if you check the output window of visual studio you will notice that the console has logged that the validating event was actually triggered twice. (The event runs twice only when I try to click a RadButton or a RadLabel)
I noticed this bug when I was checking my queries in SQL Server Profiler & the query gets executed twice, which is unnecessary. I also checked with actual wincontrols & this issue doesn't exist in them.
How do I fix this issue ?
Here a sample code to replicate the behavior
Private Sub RadTextBox1_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles RadTextBox1.Validating
Console.WriteLine("VALIDATING EVENT TRIGGERED")
e.Cancel = True
End Sub
It seems as a known issue with RadTextBox: issue link
Perhaps you can try RadTextBoxControl for your needs?
I have a simple Windows form in VB: textbox bound thru an adapter and a bindingsource to my dataset.
I have a button that on Click I want it to update the database. The form loads and the first data row shows in the textbox, I change the text then click my button but no update happens.
Any ideas what I'm doing wrong, or how I should do this??
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Me.AToolsTableAdapter.Fill(Me.Qedsandb_TroyDataSet.aTools)
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
AToolsTableAdapter.Update(Qedsandb_TroyDataSet.aTools)
End Sub
End Class
Assuming the click event runs(?), TableAdapters based on a query (a join) do not, by default, have the ability to update the database. The name of your binding source suggests that you are using a query.
MSDN: TableAdapter Overview
The update functionality of a TableAdapter is dependent on how much
information is available based on the main query provided in the
TableAdapter Wizard. For example, TableAdapters that are configured to
fetch values from multiple tables (JOINs), scalar values, views, or
the results of aggregate functions are not initially created with the
ability to send updates back to the underlying database. However, you
can configure the INSERT, UPDATE and DELETE commands manually in the
Properties window.
You don't appear to be moving the data back from the form to the dataset. Try calling EndEdit on your bindingsource.
Good morning all! Myself and a co-worker are tasked with a system-wide scripting solution but neither of us are .NET programmers so we need your help.
We have a GUI that displays a radio selection box (3 options) that are the three sites where our hospitals are. We need to dropdown located on the form to fill with only the locations based on the selected radio option.
my gui http://web6.twitpic.com/img/40330741-85d91a5637f2445b322e62df17cf3351.4aef01c5-full.jpg
Here is the code behind we have so far (sorry, VB)
Public Class frmCEHLI
Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'CELocDataSet.dbo_Locations' table. You can move, or remove it, as needed.
Me.Dbo_LocationsTableAdapter.Fill(Me.CELocDataSet.dbo_Locations)
End Sub
Private Sub btnSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubmit.Click
MsgBox("Submit button has been pressed")
End Sub
End Class
For the record the Location dropdown is currently databound but its a static SELECT statement which brings us all the locations but we'd prefer it to be cleaner if it only returned the locations based on Site. We are using Visual Basic 2008 Express Edition for development. Any help/code is appreciated, thanks!
Sorry not to respond back sooner, busy, and wanted to dig up a sample that did just what you were needing.
Create two comboboxes on your form. You can bind either fixed values, or from a table on the first combo. Then, from the property/events sheet, first set the "AutoPostBack" to TRUE, then on the events, click for the "SelectedIndexChanged" event to bring up some code.
The "Sender" object parameter will be the combobox itself, so you'll be able to analyse the property settings via debugging to find what key/value was chosen.
Then, run whatever query from your data querying control, business object, or whatever that gets your results, such as to a DataSet or DataTable.
Finally, set the datasource of your second combo to the above result query, set dataTextField and DataValueField and issue DataBind() to the combo.
That should get exactly what you need.
Then, when someone makes a selection from the second combo, you can have code within ITS "SelectedIndexChanged" event (also based on its AutoPostBack or actual submit button on the form).
Hope this helps.
I would create two combobox controls... One for the "where", then, on the InteractiveChange event by the user to post-back to the page using that answer for the second combobox of locations based on the "where" value of the first combo.