Triggering Event Handlers When The User Makes An Input Into A Combo Box?
Dec 9, 2011
This is a spin-off post from another issue I am working on. The problem is related to triggering event handlers when the user makes an input into a combo box, you might even call this a complaint.I have a combobox with a DataSource and ValueMember and DisplayMember. There is no DataBindings to worry about at this point. The combobox is DropDownStyle = DropDown and I havealso enabled AutoCompleteSource = ListSource and AutoCompleteMode = SuggestAppend.The datasource contains a list of Countires, and when the user types in an entry or chooses an entry from the combobox, I should be able to detect what the user has selected ortyped immediatley after the selection, some would say it's the very purpose of the combo box.Which event would you choose to deterine what the user has entered or Selected? few events come to mind:
SelectedValueChanged
SelectedIndexChanged
Validating
[code].....
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Nov 25, 2008
Using VB 2008 Express I have a form in which a number of controls which have event handlers to monitor choices the user is making. The event handlers do work as expected, but the problem I'm having shows up when I load the form.For example, I have:
Code:
Private Sub RadioButton6_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton6.CheckedChanged
MsgBox("I got checked!", MsgBoxStyle.Critical)
End Sub
When I load the form in question from the main form of the program, I get the message box, even though the user hasn't actually clicked the radio box. The problem arises when I try to use a call to a function that works fine, as long as the entire form has loaded. Called prematurely, the function fails.How do I solve this so these event handlers don't trigger when the form is being loaded?
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Jul 27, 2011
I tried to use this code in the form:
AddHandler MyControl.MouseDown, AddressOf StartDrag
This wont give me an error, but it doesn't happen anything when I mouse down on the Control.
the same doesn't work if I put it in the user control.
Private Sub StartDrag(ByVal sender As Object, ByVal e As MouseEventArgs)
Dim Box = CType(sender, Control)
Box.Tag = New DragInfo(Form.MousePosition, Box.Location)
End Sub
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Feb 7, 2011
The following zipped up Visual Studio Solution on Skydrive is immediately buildable and runnable; a usercontrol on a Form. Problem? If you click on any of the Edit Buttons and move the Horizontal Scroll, the values as they change in the Label_Values are off by one when you release the slider button. I think this is a timing problem between the Paint handler and the Horizontal Scroll event handler at the very bottom of the User Control code. Sorry I didn't eliminate
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Jul 10, 2009
I am writing an app that uses a combo box to list file types for a user to select from. Because a complete list of all options is both impossible and wildly unwieldy, I am only providing about 10 common extensions. I want the user to be able to type in their own file extension if the one they need is not listed. the first item in the combo box is empty by default, but during testing when i type something in their to use as my selection, i get the exception "Object reference not set to an instance of an object." pointed at extensionComboBox.SelectedItem.ToString
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Jul 28, 2011
i have a combo box without a list of item now i want to do is when a user input a number or text in combo box the text value of the combo box will be saved and when the user input the same number the combo box will not save the same text value. and when the user logout and login back again i want to load the list of item that he or she inputted earlier in the combo box.
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Aug 6, 2009
I am using a Combo box control to select from a list of Databases, and when one entry is selected I display a listbox of certain objects in the database.Other controls are then used to filter the list based on either name or content.Now, I want to know how to Re-load the original list based on the current combo box selection by using a 'Reload' button.In the button code I am setting focus back to the combo box, but whatever I try I cannot make the list refresh again. I've tried Select, SelectedItem, Text and Find methods but nothing works.How do I reload the listbox without having to manually use the drop-down and select the same item again?
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Jan 31, 2009
I have only started using VB yesterday and have managed to make some very basic programs run. What I am trying to do now is design a program that will play 4 different sound files depending on the position of a joystick. I am not looking for any kind of gradient to be involved. Any kind of forward position should play the file associated with "forward". Any kind of left position should play the file associated with "left". And the same for "back" and "right".
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Sep 24, 2010
When I utilize AddHandler in VB to add my own method to the Click event :
AddHandler Button.Click, AddressOf myButton_Click
I see that my code executes last - after other event handlers for the Button_Click event. Is there a way to insert my event handler in front of other events so that it executes first?
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Feb 24, 2011
am developing a basic "stock tracking system" in VB.Net with an Access Database for my final year project, and I am in need of help with some issues that I am still facing.System:The user basically selects a customer, selects the product, batch number, quantity, and date that the customer has chosen, and gives a summary of the transaction.I am then generating a summary report via the report wizard tool to show stock levels, and info on which customers bought what product.My Database contains 3 tables: Customer, Product, TransactionI can currently write to both the customer and product tables, bit i havnt figured out how to save a transaction record yet?, also, I am saving to the product table from a "Deliveries Form" that I have for entering incoming products. But I have not yet figureed out how to subtract the quantity values in the product table from the "Purchasing Form"? This is a major issue)en the user selects a customer from the dropdown box, that customers details is displayed in a label on the next form for the users benefit. This works when I hard-code the customer ID to be 2 for example, but it doesnt seem to recognise the "gCustomerID" (I have gCustomerID declared Global Variables module file)I think that this is the problem?
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Apr 7, 2010
Now what i want is that when user select some option from the combobox then some of the cells only in the same row get filled automatically according to the selected option.
like if there are 4 fields in grid : emp_id , name , age , salary
and id column is of type combobox then on selecting the particular emp_id from the list , its coressponding name get displayed in the same row and then user can enter the other fields.similarlly when the emp_id get selected in the 2nd row of grid then 2nd row column "name" get filled.
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Oct 19, 2010
So right now it all looks pretty with ... <button type="submit" runat="server" name="subscribe" id="Button1" class="link-button" onserverclick="saveListing"> Until it is time to validate the data before calling saveListing function codebehind (in VB .Net). How can true/false be return so that when true saveListing will be called, otherwise not?
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Jan 27, 2011
I would like to do something like the following:
Public Class Form1
Public Event Evt1(ByVal c As c1)
Public Event Evt2(ByVal c As c2)
[code]...
However, it seems to be invalid syntax, as the signature of OnEvt1OrEvt2 doesn't match that of Evt2.
Edit: The above code seems to work fine for everyone but me, but it doesn't compile for me in VS2005 SP1.The error message is something like:Error BC31029: The method 'Private Sub OnEvt1OrEvt2(c As WindowsApplication1.c1)' can not handle the event 'Public Event Evt2(c As WindowsApplication1.c2)' because the signatures do not match.
[code]....
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Feb 9, 2011
event handlers need to exactly match the event signature?
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Mar 6, 2011
is it allowed to use more than one Sub to handle the same event ? For example , may I have 2 separate subs to handle the Load event of a form ? Will they fight each other ?I have tested it and it seems to work fine , nevertheless I thought I'd ask you . In case you wonder , there is no great deal , I just want to copy the same lines of code in more forms so I am doing it just in favor of the looking aspect .
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Jun 11, 2011
I have a checkbox X1 that if checked it will check a column of checkboxes.What i'm trying to do is if the user unchecks at least one checkbox from the column it will uncheck checkbox X1. But I don't want it to run the event from checkbox X1 again because that will cause the whole column of checkboxes to be unchecked.
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Mar 6, 2011
I want to make something like an alarm clock. So, I want my programe to trigger a certain event at lets say, 8:00 AM and 16:00 PM.
I was thinking something with timers ticking every second and checking if the time I want is equal to the system time. But....I didn't manage to make it work. So, how do I make this work ?
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May 28, 2011
I have a TreeView object on my form, with check boxes. By the way, I'm working with vb.NET. I want it to perform a few different things with the aftercheck event:
If you check a node, check all its children
If you uncheck a node, uncheck the parent node
If you uncheck a node, uncheck all its children
The problem is when you uncheck a node, it unchecks its parent node, which triggers the event again and unchecks all its children.
Would there be a way to prevent the event from triggering a second time? Or will I have to give up on one of those two points?
Here's the code, if it helps any:
If e.Node.Level > 0 Then
If e.Node.Checked = False Then
If e.Node.Parent.Checked = True Then
[code]....
While I'm at it, is there a way to check if a folder is accessible? I've toyed with FileAttributes, but can't seem to find out how to make it work...
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Mar 31, 2012
I need a simple system that allows one process to check if another process is running (I think I can do that fine using Process.getProcessByName or similar) and then trigger an event in that process assuming it is.When I say trigger an event I do not mean that literally. I simply need to trigger a sub in the first process from the second.I know that IPC like this would normally be done with pipes or remoting or something like that but I have no experience with these and am looking for a quick solution, so unless these can be used relatively easily to solve this I am looking for an alternative.
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Jul 11, 2010
I have a panel control on a win form, to which I dynamically add a custom control.The custom control inherits UserControls and in the New() sub, I assign the control a GUID.When a control is added to the form, a variable of type List(Of T) holds the details of where i put the control and the size of it.
Within the custom control class there is a delete method. When the method, which deletes the custom control, is run I want the details of that custom control removed.I think I need to use event handlers but I do not know how to handle these when the controls are added dynamically.
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Jun 26, 2012
I'm converting an old VB form to .NET, and there a few Buttons which each have a corresponding ComboBox hiding behind them. The previous behavior was that you'd click the Button, and that would trigger the ComboBox behind it, which would then drop down a selection list. I believe the idea was to have a static color and text label (which cannot be a selectable option in the drop-down list), with the functionality of a ComboBox.
Now, in VB.NET, clicking on the Button (which is directly over the ComboBox in the form) won't trigger the ComboBox dropdown anymore. However, if I make the ComboBox visible enough to click on, it will trigger the ComboBox.TextChanged event, and show the drop-down (they're set to the DropDownList style). I've set the event handler to handle both that event and the Button event. I've tried Button.MouseDown, Button.MouseClick, and Button.Click -- none of which have worked.
I did find the SplitButton control option suggested here, which would probably do the job, but I don't want to have to integrate a non-native control for just 3 buttons. I don't really want to mess with the control template, either
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Jul 6, 2009
I'm trying to reset a form after a game has been played. I used checkboxes to indicate when the user picked a particular line item to update and then flagged the checkbox as checked and disabled.Once all the checkboxes have been checked, the game is over and I want to show a dialog (msgbox) that will allow the user to start a new game or exit the app. To reset the form, I was changing all the checkstates back to unchecked (along with resetting other variables), but the checkchanged events are being triggered and I end up in a loop.Is there a way to change the checkstate without triggering the event?[code]....
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Nov 6, 2011
Any sample code that will cause the logic coded in the clicked event of a Button to be executed, in Powerbuilder I would code it as
Button,triggerevent(Clicked!)
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Mar 9, 2010
with vb.net exp08 + access03
i want to check if the user not triggering any events in the application for => 30 min then i want the application to log off
how to do it ?
i am using two timers for the purpose to elapse the time but it is hard to call the function for every control + event
hence i am looking for a universal code which detects any kind of event and activate / deavtivate my timers
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Dec 27, 2009
I'm using a Datagridview my task is when the key F5 press using Keydown event executing some code
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Nov 1, 2011
I'm having a strange problem with the OnClick event. In an ArcGIS application using VB.Net, I have a button set up with the following
AddItem("CommandAnalyseResults")
The following module segment contains the OnClick event: Public NotInheritable Class CommandAnalyseResults
Inherits BaseTool <more code...>
Public Overrides Sub OnClick()
[Code]...
The OnClick event gets triggered no problem the first time I click on the button. However if I then close the window the button code creates and then click on the button again, the OnClick code is not triggered.
If I click on a different button then click back on the 'problem' button a 2nd time, it does seem to trigger the code!
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Jan 25, 2010
I want to set an event handler only if this is not set:
If GetHandlers(MyWindow.Closed, AddressOf MyWindow_Closed).Length = 0 Then
AddHandler MyWindow.Closed, AddressOf MyWindow_Closed
EndIf
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Apr 27, 2010
I have a problem, in Winform or mobile developing, When I newed some buttons in my code(never drew on the form), how can I add the click events to them and use it?
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Oct 17, 2009
How do I create an event with many handlers. I use the followingo code but it failed. Am I missing something?
Protected Sub myhandler_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles CrdCb1.CheckedChanged, CrdCb2.CheckedChanged
End Sub
[code].....
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Feb 4, 2009
how many handlers are tied to an event?
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