Dynamic Number Of Controls At Run Time
Aug 7, 2010
I am developing a form where I want the user to enter a complete recipe. In any recipe, I have no way to know how many different ingredients or how many steps will be involved. So if I am using a row consisting of a textbox, a combobox, and a textbox to represent 1 ingredient. how do I generate a dynamic number of these controls at run time? I have the same problem when I store the steps in creating the recipe. I need to create a dynamic number of textboxes to record each step.
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May 8, 2011
i have created a dynamic tabpage and a dynamic tablelayoutpanel inside it then added dynamic textboxes and labels inside the tablelayoutpanel...the thing is , i am having a problem on how to access the value of those textboxes and labels and add them as new columns in the new table(tagpage) in mysql database, i can already create the table in the database but i cant add the new columns in it. heres the code for accessing the values of the labels and textboxes
error: NullReferenceException was unhandled....Object variable or With block variable not set.
sql = "alter table " & tbl_selected(counter) & " add " & frmMain.Controls("TLP_" & SecArrList_sp(counter2)).controls.item(SecArrList_sp(counter2) & "label" & counter).Text & " varchar(100) NULL;"
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Feb 5, 2010
I would like to bind a DataGridView to a different LINQ query every time (in order to reuse the same form/DGV for different queries), like this:
[Code]....
but the "Qry", and the number of comboboxes, and their field names would change every time.
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Sep 17, 2010
I have a query about dynamically added controls to a form. I have a series of buttons which are created and added at run time. I have a two drop down lists and two buttons which are created at design time. Button 1 creates a series of buttons called "Test 1.x" based upon the selection of the two drop down lists. This works fine and am happy with the logic.However.... Button two should remove all the dynamically created buttons from the form.This does not happen. What does happen is that 50% of the buttons are removed starting with the first one. WHen checking the loop it only enters the loop half the amount of times that there are buttons. Very strange. When the loop is run repeatability it will remove all controls. Why will my logic not remove all the dynamically created controls at once? What is wrong with my logic?
I attach two code snippets and the .net file for your consideration.Button method which creates the dynamically created buttons from the two drop down lists and adds to form
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim Count As Integer
Dim MaxHours As Integer
[code]....
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Aug 23, 2011
There is newer code in a follow up post. I suggest using the code in the later post rather than the code in this one. You can still read this post though. When designing a user interface, one should be conscious of how many individual controls are required to implement the functionality. In some cases an initial design may begin with many buttons or textboxes (for example) but then further review of
the actual required functionality allows for a reduction in the number of unique controls.
But other times, there isn't a better way (which will still make sense to the user of the application) then to have a series of many repeated controls. So in the cases where one can be certain that the best UI implementation for an application will require the use of multiple copies of a given control, then it often becomes necessary to maintain some method of managing all of those controls at various points
throughout the application. Doing so typically requires that one build up some collection of controls which can then be accessed by index in order to work with any given control; but this can lead to a lot of clutter in the code file which handles these control's events. For instance there will be some kind of collection declaration, some recursive routine to find all of the controls of interest, and then any number of event handler methods with long lists of Handles clauses, or additional code loops to wire up the event handling for each control.
Purpose Since most of this functionality could be considered a requirement regardless of the type of control being managed, or its required functionality, it may make sense to wrap all of the control management functionality into a single class. And since our first requirement is a collection of controls, then a base collection class could be the perfect starting point for our control manager. There are a number of existing thread around this topic, with some recent (at the time of this writing) ones being:[URL]..In this, and related, threads I have posted examples of a simple TextBoxManager and ButtonManager control. But again, with so much similar functionality required regardless of the control being managed, it would be technically possible to create a generic ControlManager(Of T As Control) class which can manage any type of control.
[Code]...
So in summary, one can facilitate managing a large number of user interface controls by building a "control manager" class which both encapsulates the list of control instances, and deals with adding and removing defined event handlers for every control it manages. The generic control manager class itself can be inherited and extended into a more specific class on a per-application basis in order to provide more application-specific functionality. Reed Kimble - "When you do things right, people won't be sure you've done anything at all"
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Nov 20, 2011
I've got a couple of these NumericUpDown controls I put on a form. Without describing too much about the form I basically want to update some variables each time one of these NumUD controls changes value. So for each NumUD I have a call to a Recalculate subroutine within their "changedValue" event.
There are actually two problems. First, if I initialize the "Value" property to something other than zero in VB2010 at DESIGN TIME it won't even open the form when I hit RUN. It gives me a "No Source Available. No symbols loaded for any call stack frame" error. The error box says "InvalidOperationException" was not handled. So if I try to set the initial value of the Value property to anything but zero of either I get this error.
[Code]...
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May 13, 2009
I've been building controls for many years professionally and personally, but even back in VB6 days I just could not work this out. After all this time I remembered about it again.If I create a usercontrol/containercontrol and add one or more controls to the controls surface, I just cannot figure out how to access the controls at design time.
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Nov 2, 2011
In VB if you prompt the user for a number between 1-20, then a word, how do you get a text box to show the word the same number of time as the number selected using loops?... Ex: please select a number: 4 / select a word: cat....the text box should display ::: catcatcatcat ........
I am doing this for a class and my brain has locked up. Prob. just over thinking it though. Thanks in advance for any help!
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Mar 7, 2010
I have 10 labels named lbl1, lbl2, ... lbl10
I'd like to change their propriety (using a cicle) with the cicle index
for i as integer=1 to 10 step 1
lbl (i) = PROPRETY 'I know this is wrong but it's what I would do...
end for
I'm using a workaround, but I'm looking for a better way..
[Code]...
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Nov 5, 2011
I have a VB.Net WinForm Program. I dynamically create panels with controls.Each panel has:
2 Labels
1 DataGridView
1 Button
Everything works fine the first time I create the panels.
Everything gets created, and everything is functional.
If I have to re-create the form, I get rid of the existing panels (and their controls) with this code:
[Code]...
When I re-create the panels, I get the panels and all of their controls except Buttons.When I step through the debugger, I see the buttons being removed, and I see them being created, but they don't appear in the panel
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Aug 9, 2010
I am working on VB.NETPresent i am working on Dynamic Controls.As per below sending my Code ...... I was Created....First Step: i was Created CheckBox Controls Dynamically in the loop.Second Step: i was Created One more CheckBox Control name called 'AllProjects".
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
cn.ConnectionString = ("Provider=Microsoft.jet.OLEDB.4.0;Data
[code].....
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Oct 12, 2009
How would you add Dynamic controls to your form, from an array which size may vary depending on how many controls the user has selected and has been retrieved from a database?
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Jan 19, 2010
I am programmatically adding some custom user controls to a PlaceHolder which I have on a simple aspx page. All of the user controls Postback's work correctly except for one which has a Gridview on it.
For some reason any postback that gets fired from within this control, does not call the specified event on the first click, however all future clicks it will work fine. I have no idea why this is the case, but many solutions I have found, suggest adding an ID to the ascx User Control, however this doesn't work in my case.
I've taken a look at the source file for the page that gets generated before and after the first click, javascript used for calling the postback changes, i.e
Before first click: onclick="javascript:__doPostBack('tmpControlID$sgvPrimaryEmploymentHistory','Select$0')"
After first click:
[Code]....
Again, nothing overly complicated. The USERCONTROLNAME is just a const with the value "tmpControlID" in it.
The control that is giving me trouble is a little complicated, I was originally using a custom GridView control that we have created, but have removed it and replaced it with the standard asp one to see if the problem still occurs, and it does.
Any button, on control which fires off a postback will fail the first time, and all future click will work correctly. On the first click the Page_Load event will get called, but that is it.
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Mar 4, 2012
Previous in my app, I've created dynamic controls and and named them blah0, blah1, blah2 etc. There will be a different amount created each time the user runs the app.I'm now trying to delete all of the controls but doing something very wrong. I've got the following
dim checkboxes = Controls.OfType(Of CheckBox).AsQueryable()
dim sPrefix as string = "blah"
for each checknum as checkbox in checkboxes
[code]....
When I execute the above, it only gets rid of every second control and I have no idea why. If I swap the dispose with a msgbox, the msgbox appears every time as I'd expect. It would seem that disposing of a checkbox seems to somehow requery the number available?
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Jun 6, 2011
i have a form with many dynamic controls. i want to add an item to a listbox ( by the way, to find this listbox i'm using 'tag'. if someone have any other idea i'll be hope to hear but that's not the problem) in order to do so i use this
For Each ctl As Control In Me.Controls
If TypeOf ctl Is ListBox Then
ctl.items.add("i want to add this line")
[code]....
and items is not recognized and this eror massage apear: 'items' is not a member of 'System.Windows.Forms.Control'.
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Apr 13, 2009
i have two controls consider two text box, as i enter a value in one text box the other should also be updated with the same. I used handlers but the problem with that is only when i leave the control the other gets updated i need it to be dynamically updated.
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May 1, 2010
how i can program a dynamic controls(list view, datagrid, combo box, etc..)
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Aug 6, 2012
I am creating a page with an area name and an input box next to it, code below:
Dim SQLConnection As New Data.SqlClient.SqlConnection(System.Configuration.ConfigurationManager.AppSettings("sqlstr"))
Dim cmd As New SqlCommand
Dim LoadAreaReader As SqlDataReader
cmd.CommandText = "ListAreas"
[code]....
This works great, the problem I am having now it retreiving the details once Button1 is clicked. I got as far as this:
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
For Each key As String In Request.Form.AllKeys
If key.Contains("txtPrompt-") Then
[code]....
But just need to display the id of the input box that has a value of more than 0. Am I close at all?
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Mar 16, 2012
I'm having problems removing dynamic controls.
Here is what I'm using:
CODE:
The first sub is for adding the (custom)control, the second sub is for removing the control.
The custom control is a picturebox with a checkbox in the upper-left hand corner, no big deal.
The problem is that when I click the delete command, it only deletes one ckPicture at a time, and allways the last one in the list. I'm also assuming it's doing the same thing in the list(of images). What should I do differently so that it will remove all controls that are checked?
I forgot to add the variables in my namespace.
CODE:
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Jun 27, 2012
I've volunteered for a simple webform survey for customers and I've stuck on creating dynamic controls/ lables for the questions.. The number of questions will vary so I'd hate to change this webform everytime.[code]....
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Mar 16, 2011
I have an Application that has a tab control on it. Depending what the end user clicks on, a new tab is created dynamically at runtime and I use a Template class to fill it with controls of what is needed for the type of tab being created. All works fine but where I have an issue is with the dynamic tooltip control. I added a tooltip to the main form and added code to access it in the Template Class. But I feel I have to rig it to get it to work and am looking for a more proper way to do it. I access the Tooltip1 on Form1 via Form1.components. However, "Components" in the Form1 designer code is declared Private and I change it to Public and it works fine but of course as I know when I make changes to the Design of Form1 it recreates the code and Chages the Componets back to Private. So I need a better way to access it or a better way to create Tooltips dynamically.
Code:
'---CreateTab Class--- a portion of code for example
CreateTab(ByRef tpNew As TabPage)
Dim btnSelect = New System.Windows.Forms.Button
[Code].....
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May 28, 2011
converting the number of frames (in a video) to a number/time format. For instance, say a video has 110,212 frames at 23.976 fps, it works out to 01:16:36 (hh:mm:ss) with 18 frames remaining. I would like to format the result in a Textbox like the following:
[Code]...
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Jan 31, 2009
I created a listbox using VB.NET. When the user select an item (it is a string format) in the listbox and click on a button, there will be a number beside the string and the number will increment which time the button is clicked. Anyone know how to do it...?Below is the coding I'd done, but I don't know how to do the increment part. Anyone know what coding I need to add?
Dim no As Integer = 0
listBox.Items.Add(listBox.SelectedItem & no)
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Jun 9, 2011
Just getting started in VB.NET. I would like to add X-number of text boxes at run time. And then be able to address them by their index or some sequential numerical value (like an array)
This is what I have so far:
CODE:
When I turn this into a loop to create multiple toolboxes, how do I assign a name to the controls, or will all of them be named "MyTextBox" ? I'll increment their position so thats no problem.
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Jun 10, 2012
Create a web browser with tabs and I want to add a "Open in a new Link" Button with a Custom Menu .
The problem is I'm trying to use a Dynamic Control(Webbrowser) created in a class from a local sub (A picture box) on the event click . But i get this error [code]....
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Jan 9, 2009
I am writing an application that requires button controls to be created at run time because the amoutn of controls created depends on data retrieved from a database.
I believe I am creating the control properly but I am not capturing the click event.
Code example:
Dim myButton As Button
myButton = New Button
myButton.id = "id"
[Code]....
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Feb 10, 2011
How to define handler events for dynamic controls.
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Aug 2, 2011
First problem: Clicking the addsplit image adds another row with the same data but an increased value to the end but when the 6th row is added (displays the scrollbar), only the bottom 5 addsplit image works (when scrolled to the bottom) instead of all of them working. How can I ensure that when the image is clicked, the scrollbar automatically scrolls to the bottom and also how to make all addsplit image work instead of the bottom 5 only?[code]....
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May 29, 2012
I have the following dynamic controls...working great..
[Code]...
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Oct 31, 2011
I'm having trouble getting controls in non active tabs to update. I have a tab control with 12 tabs. Each tab displays a custom calendar of days for each month. For each of the days I used label controls. Now the trouble im having is when I re-size the window I want the day labels in each tab to re-size accordingly. I have the re-size function written and working but for some reason it will only re-size the active tab. In order for me to have the labels on the other tabs update to the re-size I need to open each tab as to load it then it will update the controls.I've tried putting Application.DoEvents() in my re-size loop but that didn't work. How can I get the other tabs to update / redraw the controls without having to open the tabs first?
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