From a FormName2, and I need to set a text in a TextboxName1 that is in a FormName1, by their string names.
Then, from FormName2, I should set the text like FormName1.TextboxName1.text = "test".
However, I need to achieve it with string names of the controls.
stringFormName.stringTextboxName.text ="test"
How to reach it?
You could retrieve all the opened instances of your forms in the Application.OpenForms collection.
Using that collection you can retrieve the form with the specified name
Dim aForm = Application.OpenForms.Item("FormName1")
At this point, you can scan the controls of this form with the same pattern for a control with a specific name
If aForm IsNot Nothing Then
Dim aControl = aForm.Controls.Item("TextBoxName1")
if aControl IsNot Nothing then
aControl.Text = "test"
End If
End If
The only problem with this search for a control is the possibility of the control to be contained in a control container different from the top level form. For example the control could be inside a GroupBox or a Panel. In this case you need to use the Find method from the Control collection with the second parameter set to true to search all the control hierarchy
Dim aControl = aForm.Controls.Find("TextBoxName1", True)
Use FindControl:
Private Sub Button1_Click(sender As Object, MyEventArgs As EventArgs)
Dim myControl1 As Control = FormName1.FindControl("stringTextboxName")
If (Not myControl1 Is Nothing)
' Get control's parent.
Dim tb as TextBox= CType(myControl1, TextBox)
tb.text="test"
Else
Console.WriteLine("Control not found.....")
End If
End Sub
If you have nested elements you may need to call find control recursively.
Related
I'm new to visual basic and programming in general, but I'm trying to make a statistic counter sort of program. I'm trying to use a variable to reference a textbox, for example, k_kills(i) = txtKills(i).Text. This doesn't work, however, so I then tried the following:
For i = 0 To 8
Dim tempBox As TextBox
Dim tempName As String = "txtKills" & i.ToString
tempBox = Me.Controls.Item(tempName)
k_kills(i) = tempBox.Text
Next
This also doesn't work and spits out an error each time saying that 'tempBox was Nothing'.
Can anyone tell me if I can make this work?
Thanks.
You will need to find the control in some collection. By default the control would exist in its parent's Controls property and since you're trying to get the control by its name then you could use ControlCollection's Find method. If you can guarantee that the control's parent is the Form then you'd call:
Dim tempBox As TextBox = DirectCast(Me.Controls.Find(tempName, False), TextBox)
But if there is the possibility that the control's parent is something other than the Form then you'd call:
Dim tempBox As TextBox = DirectCast(Me.Controls.Find(tempName, True), TextBox)
The first would execute slightly quicker because it only iterates over the current ControlCollection whereas the second could take longer because if it cannot find the control in the current ControlCollection then it starts to iterate over the child controls as well.
Assuming the controls are all in Form as parent and they all start with txtKills...
If you are going to use these text boxes as a group for several actions you may want to build an array or list of TextBox.
Dim Kills(7) As TextBox
Private Sub CreateTextBoxArray()
Dim index As Integer
For Each ctrl As Control In Controls
If ctrl.Name.StartsWith("txtKills") Then
Kills(index) = DirectCast(ctrl, TextBox)
index += 1
End If
Next
End Sub
Private Sub ClearKillTextBoxes()
For Each t In Kills
t.Clear()
Next
End Sub
Private Function GetTextFromKillBoxes() As List(Of String)
Dim lst As New List(Of String)
For Each t In Kills
lst.Add(t.Text)
Next
Return lst
End Function
After Mary's comment I edit my answer to add this line --> My code does not work if Option Strict is On and 'For' starting in 0 or 1 or any number and txtKills[X] exists.
This was my previous answer and I don't know if I have to delete or not:
Your code works fine but I think you have an error because your For starts in 0 and you don't have any "txtKills0". I've tested it now:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim k_kills(10) As String '<< Ignore the length
For i = 1 To 7
Dim tempBox As TextBox
Dim tempName As String = "txtKills" & i.ToString
tempBox = Me.Controls.Item(tempName)
k_kills(i) = tempBox.Text
MsgBox(k_kills(i))
Next
End Sub
Here's my problem:
I have a form with a treeview.
That treeview shows all:
other forms in my project as parents
all buttonnames as childs
all buttontags as childs of the buttonnames.
When i select a buttonname in the treeview i have the selection presented as
(textbox1 with the buttonname)
(textbox2 with the buttontag)
(textbox3 with the formname)
I have 1 empty textbox which i want to fill manually, to update the buttontag from the button selected in the treeview.
Either way, all code I have tried ain't updating anything.
This is the code so far, but doesn't seem to work...
My Code:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim asm = System.Reflection.Assembly.GetExecutingAssembly
Dim myTypes As Type() = asm.GetTypes()
Dim frm As Form
For Each t As Type In myTypes
If t.IsSubclassOf(GetType(System.Windows.Forms.Form)) AndAlso TextBox1.Text = t.Name Then
frm = CType(Activator.CreateInstance(t), Form)
frm.Hide()
Dim thisButtonName As String = TextBox3.Text ' This is the name of the button I'm looking for
Dim thisButtonName2 As String = TextBox2.Text ' this is the new tag name for that button
' Loop all controls in this form
For Each ctrl As Control In Controls
' Is this control a button
If TypeOf (ctrl) Is Button Then
' Is this the correct button
If CType(ctrl, Button).Name = thisButtonName Then
CType(ctrl, Button).Tag = thisButtonName2
End If
End If
Next
End If
Next
TreeView1.Nodes.Clear()
For Each formprop In My.Forms.GetType.GetProperties
Dim node = Me.TreeView1.Nodes.Add(formprop.Name)
Dim form As Form = CType(formprop.GetValue(My.Forms, Nothing), Form)
ControlsTree(node, form.Controls)
Next
End Sub
I think there are two basic problems here:
Your loop For Each ctrl As Control In Controls is not iterating over the controls in the other form object referenced by the frm variable. The Controls property is going to default to this form's set of Controls, not frm.Controls.
It seems like you are trying to change the Tag in the definition of that class at run-time. That is not possible, AFAIK, especially in what you're trying here. Each time you create a new instance of that form object, you are going to get that object initialized as how it was compiled. You can change the Tag values of a running instance of the object, but you can't change the default values of the class without using a technique like dependency injection.
Is there a way that I can use a variable to control which PictureBox I am using in Visual Basic?
I.e.:
CurrentNumber = 1
PictureBox(CurrentNumber).backcolour = backcolour
You can use the Me.Controls(String) indexer. It lets you specify the name (as a string) of the control you want to access, thus you can dynamically access a picture box by concatenating the string "PictureBox" with a number.
Dim TargetPictureBox As PictureBox = TryCast(Me.Controls("PictureBox" & CurrentNumber), PictureBox)
'Verifying that the control exists and that it was indeed a PictureBox.
If TargetPictureBox IsNot Nothing Then
TargetPictureBox.BackColor = Color.Red
End If
Alternatively, to save processing power by avoiding looping through the entire control collection every time you can call the OfType() extension on Me.Controls, storing the result in an array sorted by the controls' names. That way it'd only have to iterate the control collection once.
'Class level - outside any methods (subs or functions).
Dim PictureBoxes As PictureBox() = Nothing
'Doesn't necessarily have to be done in a button, it's just an example.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If PictureBoxes Is Nothing Then
PictureBoxes = Me.Controls.OfType(Of PictureBox).OrderBy(Function(p As PictureBox) p.Name).ToArray()
End If
'NOTE: CurrentNumber - 1 is necessary when using an array!
PictureBoxes(CurrentNumber - 1).BackColor = Color.Red
End Sub
NOTE: This solution will only work properly if all your picture boxes are named "PictureBox1", "PictureBox2", etc. If you suddenly skip a number ("PictureBox3", "PictureBox5", "PictureBox6") then PictureBoxes(CurrentNumber - 1) for CurrentNumber = 5 would return PictureBox6 rather than PictureBox5.
What you really should do is create a PictureBox() and use that to reference your picture boxes via an index.
The best way to build your array is to create a method that builds the array from the references created by the designer. This lets you continue to use the designer to create your controls and it makes your code check for deleted controls at design-time. Using Me.Controls(...) suffers from run-time errors if controls you are looking for have been deleted.
Here's the code you need:
Private _PictureBoxes As PictureBox() = Nothing
Sub AssignPictureBoxesArray
_PictureBoxes = {PictureBox1, PictureBox2, PictureBox3}
End Sub
Then you access them like this:
Sub SomeMethod
Dim CurrentNumber = 1
Dim PictureBox = _PictureBoxes(CurrentNumber - 1)
PictureBox.BackColor = System.Drawing.Color.Red
End Sub
I am making a grade application for a school project and I am wondering how I can loop through and check a value in all combo boxes on a certain form, I have 19 units to check; trying to be efficient without making 19 case statements. I have tried an array and me.controls.
Try this :
For Each c As Control In Me.Controls.OfType(Of ComboBox)()
'You cann acces to ComboBox her by c
Next
Note that if you have controls host by containers (TabControl, SPlitPanel, etc.) you may not find all of your controls.
Here is a recursive call that should return all of your controls:
Sub GetControlList(container As Control, ByVal ctlList As List(Of Control))
For Each child As Control In container.Controls
ctlList.Add(child)
If (child.HasChildren) Then
GetControlList(child, ctlList)
End If
Next
End Sub
I have on occasion had problems with the controls on SplitContainer panels so if you use a splitter make sure you are getting all your controls.
Once you have a complete list of controls you can operate on them. This sample is working with DataGridView controls:
Dim ctrls As New List(Of Control)
GetControlList(Me, ctrls)
For Each dgv As DataGridView In ctrls.OfType(Of DataGridView)()
AddHandler dgv.DataError, AddressOf DataGridView_DataError
Debug.Print(dgv.Name)
Next
FYI the generic data error code:
Private Sub DataGridView_DataError(sender As Object, e As DataGridViewDataErrorEventArgs)
Dim dgv As DataGridView = sender
Dim sGridName As String = dgv.Name.Replace("DataGridView", "")
Dim col As DataGridViewColumn = dgv.Columns(e.ColumnIndex)
Dim sColName As String = col.HeaderText
MsgBox(sGridName & vbNewLine & "Column " & sColName & vbNewLine & e.Exception.Message, MsgBoxStyle.Exclamation)
End Sub
You already have the OfType(OF T) method. You use it like this:
ForEach box As ComboBox In MyForm.Controls.OfType(Of ComboBox)()
Next
But this only checks the direct children of your control. If you have container controls like GroupBox, Panels, FlowControlLayoutPanel, etc, you'll miss the controls nested inside them. But we can build a new OfType() method to search these recursively:
Public Module ControlExtensions
<Extension()>
Public Iterator Function OfTypeRecursive(Of T As Control)(ByVal Controls As ControlCollection) As IEnumerable(Of T)
For Each parent As Control In Controls
If parent.HasChildren Then
For Each child As Control In OfTypeRecursive(Of T)(parent.Controls)
Yield child
Next child
End If
Next parent
For Each item As Control In Controls.OfType(Of T)()
Yield item
Next item
End Function
End Module
And you use it the same way:
ForEach box As ComboBox In MyForm.Controls.OfTypeRecursive(Of ComboBox)()
Next
You'll probably want to check containers for controls of the type you're looking for, here's a little function that should do the trick for you.
Private Function GetControls(Of T)(container As Control, searchChildren As Boolean) As T()
Dim Controls As New List(Of T)
For Each Child As Control In container.Controls
If TypeOf Child Is T Then
DirectCast(Controls, IList).Add(Child)
End If
If searchChildren AndAlso Child.HasChildren Then
Controls.AddRange(GetControls(Of T)(Child, True))
End If
Next
Return Controls.ToArray()
End Function
Here's the usage, if search children is True then all child containers will be searched for the control you're looking for. Also, for the top most container we'll just pass in Me assuming you're calling the code from within your Form, otherwise you could pass the Form instance or a specific Panel, GroupBox, etc.
Dim ComboBoxes As ComboBox() = GetControls(Of ComboBox)(Me, True)
I have a form that I display exclusively with the ShowDialog method. In the Form_Shown event, I dynamically create a set of labels and text boxes based on a public variable set in the form making the call.
I understand that the form is not closed or destroyed but simply hidden between calls, and as such I added code at the top of my Form_Shown event to clear out any controls from a previous call, but the controls aren't being removed. I have tried ctrl.Dispose (as in the code below) and Me.Controls.Remove(ctrl). Neither produces an error, but the Textboxes are not removed and new ones are created over them. (For some reason,
This is the first time I've dynamically created/removed controls in .NET, so it's possible my yearning for VB6's control arrays have something to do with the error.
The form builds itself based on the calling form's public ListView variable. The calling form makes certain this variable is not nothing and that items are selected if and only if the user is editing an existing row.
Public Class frmTableEdit
Private isNew As Boolean
Private inputText() As TextBox
Private Sub FormTableEdit_Shown(sender As Object, e As EventArgs) Handles MyBase.Shown
For Each ctrl As Control In Me.Controls
If TypeOf (ctrl) Is TextBox Or TypeOf (ctrl) Is Label Then
ctrl.Dispose()
End If
Next
With frmKioskData.TBLobj
Dim fieldCount As Integer = .Columns.Count - 1
isNew = .SelectedIndices.Count = 0
'(code setting size of form and location of OK/Cancel buttons is here)
ReDim inputText(fieldCount)
For i As Integer = 0 To fieldCount
Dim lbl As New Label, txt As New TextBox
inputText(i) = txt
Me.Controls.Add(lbl)
Me.Controls.Add(txt)
'(code setting size and and position of lbl & txt is here)
'lbl.Tag = i (I commented these lines out because I never used the
'txt.Tag = i Tag property, but can if a solution calls for it.)
lbl.Text = .Columns(i).Text
If isNew Then
txt.Text = ""
Else
txt.Text = .Items(.SelectedIndices(0)).SubItems(i).Text
End If
Next
End With
End Sub
End Class
If #Plutonix's suggestion in the comment above does not quite work for you, I think it would be easiest and make more sense to dispose of the form after calling ShowDialog, and then when you need to show that form you create a new instance with a parameter that tells it what dynamic controls to load.
So you'd have a New method in frmTableEdit that uses this parameter:
Public Sub New(ByVal fieldCount As Integer)
InitializeComponent()
fieldCount = fieldCount 'Where fieldCount is a class variable
End Sub
And when you call this form from frmKioskData, you can do so like this:
Dim newTableEdit As New frmTableEdit(Me.TBLobj.Columns.Count - 1)
newTableEdit.ShowDialog()
newTableEdit.Dispose()
Then the code in your frmEditTable's Shown event just simply has to add the controls accordingly, without the need to remove old ones:
ReDim inputText(fieldCount)
For i As Integer = 0 To fieldCount
Dim lbl As New Label, txt As New TextBox
inputText(i) = txt
Me.Controls.Add(lbl)
Me.Controls.Add(txt)
'(code setting size and and position of lbl & txt is here)
'lbl.Tag = i (I commented these lines out because I never used the
'txt.Tag = i Tag property, but can if a solution calls for it.)
lbl.Text = .Columns(i).Text
If isNew Then
txt.Text = ""
Else
txt.Text = .Items(.SelectedIndices(0)).SubItems(i).Text
End If
Next
How you get the isNew value is up to you - you can add that as a second parameter to the form's New, or get it the same way you are now...w/e. If it were me I'd normally add that as another New parameter.