in VB.NET i have 2 custom controls, one is a TextBox and second one is a ComboBox.
These have custom values like Bool _IsHidden and are added on runtime to a form.
Now, at some point in the code I want to check if the _IsHidden is set to True or False and display that information. Since the user can edit this values when creating the control these are not set on creation.
So what I tried is:
(all of this is on MDI Forms)
For Each frm as CustomForm in Main.MdiChildren
If frm.MyName = calledBy Then 'this part is just to know which form called the form to create the object
For Each cntrl as CustomTextBox in frm.Controls
'DO Something
Next
End if
Next
Now.. if the first control is a custom ComboBox it thorws an error since it sees that it does not match the custom TextBox control..
how do i get around this? By my understanding it should just go through all of the controls on the said form and just check those who match CustomTextBox control ?
Thank you
For Each x As T In collection does not filter your collection items to those of type T. It tries to convert every item in collection to T and throws an exception if that fails.
Thus, you have the following options:
Do the check yourself, for example, using the code provided by RB.
Alternatively, you could filter your list first, and then loop through the items. Here, LINQ can help:
For Each cntrl In frm.Controls.OfType(Of CustomTextBox)()
... ' Do this for all CustomTextBoxes
Next
For Each cntrl In frm.Controls.OfType(Of CustomComboBox)()
... ' Do this for all CustomComboBoxes
Next
You don't need the As CustomTextBox clause here, since frm.Controls.OfType(Of CustomTextBox)() returns an IEnumerable(Of CustomTextBox), so For Each can infer by itself that cntrl must be of type CustomTextBox.
By my understanding it should just go through all of the controls on
the said form and just check those who match CustomTextBox control ?
That's not correct I'm afraid. You'll need to implement that check yourself, e.g:
For Each cntrl as object in frm.Controls
If TypeOf cntrl Is CustomTextBox Then
With CType(cntrl, CustomTextBox)
.DoSomethingWithControl()
.DoSomethingElseWithControl()
End With
End If
Next
Related
I am trying to get create a function (or some expression) that can be run from any textbox on a Form, which will return the Name of the textbox as the Value of that textbox, i.e. each box will display it's name in the box itself.
I'm looking for something like Me.ActiveControl.Name, but that only returns the same value for each textbox. Is it possible to be self-referential like that? I haven't been able to find anything that does that.
Cell? self-referential?
The answer is Me.ActiveControl.Name which does return the name of the active control (textbox).
That name doesn't change from record to record. If you wish to identify individual records, use the ID of the record or the CurrentRecord property of the form.
You can make a control the ActiveControl of the form with:
Me!TheControlName.SetFocus
or:
Me.Controls("TheControlName").SetFocus
or loop the Controls collection of the form to list the textboxes:
Dim Control As Control
For Each Control in Me.Controls
If Control.ControlType = acTextBox Then
Debug.Print Control.Name
End If
Next
I have a form with 3 textboxs and i want to change their properties values according to some events.
My idea is to set these properties to a global form's variables in order to use them whenever i want with a function or module (this depends on your suggestion).
Assuming that i want to change all textboxs.enabled property by pressing a button
and i want to change another different property if needed in the future (like bordercolor),
my example is this:
in the form VBA,
Option Compare Database
Option Explicit
Private Const AllTxtboxes = *** all txtboxes ***
in the VBA button
Private Sub button1_Click()
AllTxtboxes.enabled = True
End sub
Thanks in advance.
You need to loop trough all controls and identify those you want to change. The problem is that each control type got their own properties, so you need to make sure you are in the right one.
And for that, there is a property common to all controls named Tag
There, you can specify a value and check it. It's really helpful to select only what you want.
I made a simple form with 6 textboxes:
Note that in design view, properties panel at right, tab others, last property is Tag (sometimes it comes as aditional info or something like it).
There, I typed 99 but only on textboxes 2, 4 and 6, because those are the textboxes I want to handle (that would be kind of your array of textboxes)
I added a command button to change forecolor of those textboxes to red when clicked. My code is:
Private Sub CMD_CHANGE_FONT_COLOR_Click()
Me.Painting = False
Dim MyControl As Control
Dim MyTxt As TextBox
For Each MyControl In Me.Controls
If MyControl.Tag = 99 Then
'we set MyTxt to MyControl so we can use Intellisense, not really needed, but it makes coding easier
Set MyTxt = MyControl
MyTxt.ForeColor = vbRed
Set MyTxt = Nothing
End If
Next MyControl
Me.Painting = True
End Sub
When the form loads, you will see:
But after click on command button, the forecolor of those 3 textboxes will be red:
There you go. So everytime you want to do something with that array of textboxes, you can use this code to loop and change the properties you want.
How do I reference a dynamically named control on a UserControl from the Parent Form? (In Winforms).
I have a single parent form but it may load any 1 of around 20 or so UserControls. We will call them ucA, ucB, etc.
Each UserControl has a different number of textboxes, but are named tbA01, tbA02, etc on ucA and tbB01, tbB02, etc on ucB.
How would I reference the value of the textboxes?
I cannot seem to reference the name of the UserControl directly. I know the name of the UserControl as a string, but canot seem to cast it as a control. Likewise with the textboxes on the UserControl. I am sure I can use Control.Find() for the name of the textbox from a simple string. But this doesn't appear to be working, which I assume it will only be looking for controls on ParentForm and not the collection of controls on the UserControl. I assume there would be a method using TryCast or DirectCast and using the Control.Find() in the arguments. But I have not found a solution.
Any help would be appreciated!
Thank you Jimi! Your answer did help me look at a different method in coming up with a solution. I have it working now. Here is what I used:
Dim matches() As Control
matches = Me.Controls.Find(TblName, True)
If matches.Length > 0 AndAlso TypeOf matches(0) Is TextBox Then
Dim tb As TextBox = DirectCast(matches(0), TextBox)
...
Endif
is it possible to loop through all comboboxes with specific name. For example I have 25 comboboxes in a groupbox i need to loop through 20 of them (each of this 20 have name special_combo_1,special_combo_2 and etc. but another 5 have another names so i need to leave as they are)and change their width at once or change the text or anything else.
You can use Control.Controls to get all the controls the GroupBox contains.
Then, you should cast each Control object to the ComboBox type by using TryCast(Object, Object).
You can check the prefix with String.StartsWith(String).
For Each Item As Control In GroupBox1.Controls
Dim ComboBoxItem As ComboBox = TryCast(Item, ComboBox)
If ComboBoxItem IsNot Nothing Then
If ComboBoxItem.Name.StartsWith("special_combo_") Then
' Code here
End If
End If
Next
Use the OfType to make a collection of comboboxes from the control collection. No TryCast needed so increase in preformance. Then filter them with the Where clause to drill it down even further. Now you iterate only a small collection of controls.
Dim spComboboxes =
GroupBox1.Controls.OfType(Of Combobox)().
Where(Function(cb) cb.Name.StartsWith("special_combo_")).ToList()
Iterate the comboboxes:
For Each cb In spComboboxes
'do something
Next
i have used many of the controls in vb.net forms, including a textbox and combobox, but I want to clear all my text boxes at once, while not typing textbox1.clear() for each one.
Is there any other way to clear all my textboxes?
If I understand you question right, you should be able to loop through all the controls on your form and check to see what Control type they are. Based on their type, either set the textbox Text property to String.Empty, or your ComboBox to the index of a blank ListItem (presumably item zero).
Something like:
For Each ctrl As Control In Me.Controls
If TypeOf ctrl Is TextBox Then
CType(ctrl, TextBox).Text = String.Empty
Else
' do something similar for your ComboBox
End If
Next
You can parse through each control on your form and test what type of control that is and handle each type separately, but it is easier to simply set each control manually.
Consider writing a ClearForm routine that does all of this, that way all you have to do is call the method.