I have programmed a long time but I’m relatively new to vb.net. And I’ve avoided subroutines and functions in which I passed parameters because I always get stuck. I’m trying to write a subroutine to pass information that will fill a TextBox or a checkbox with either the value from a table or clear the field or set to false. The first code below is an example of what I’ve been doing and this works. I trying to write a subroutine to pass 1.the name of the textbox or checkbox control on my form,2.the data row value, and 3.the column name in the table. The problem is when I passed a checkbox I can’t get the checked event to show on my control(CoreCol) that I passed. It knows it’s a checkbox and it will set the text of the checkbox too true or false but it won’t change the box checked.
This is an example of the old way that works. For a TextBox and a checkbox
' A Machine
If Not IsDBNull(r("A Machine")) Or Not IsNothing(r("A Machine")) Then
TbXMachA.Text = r("A Machine")
Else
TbXMachA.Text = ""
End If
If Not IsDBNull(r("A CO2 Box?")) Or Not IsNothing(r("A CO2 Box?")) Then
CkbxCO2BoxA.Checked = r("A CO2 Box?")
Else
CkbxCO2BoxA.Checked = False
End If
This works
LoadData2TextBox(Me. TbXMachA, r, "A Machine ")
This doesn’t
LoadData2TextBox(Me.CkbxCO2BoxA, r, "A CO2 Box?")
this is the sub routine I'm writing
Private Sub LoadData2TextBox(ByRef CoreCol As Control, CoreRow As DataRow, BoxStage As String)
If Not IsDBNull(CoreRow(BoxStage)) Then
If TypeOf CoreCol Is TextBox Then
CoreCol.Text = CoreRow(BoxStage)
End If
If TypeOf CoreCol Is CheckBox Then
CoreCol.??? = CoreRow(BoxStage)
End If
Else
CoreCol.Text = ""
End If
You know that CoreCol is a CheckBox so you can cast it as one then use it as a CheckBox.
If TypeOf CoreCol Is CheckBox Then
Dim myCheckBox = DirectCast(CoreCol, CheckBox)
myCheckBox.Checked = DirectCast(CoreRow(BoxStage), Boolean)
End If
Another cast in getting the boolean value out of CoreRow(BoxStage). The above code assumes this will work, but I am not sure what is in CoreRow(BoxStage). You may need to add some logic based on the value depending on what it is. For example:
myCheckBox.Checked = CoreRow(BoxStage) = "somevalue"
Related
I am trying to generalize this Sub. The sub works, without the test for the checkbox, for text fields. A checkbox has no .BackStyle nor a .ForeColor property.
I tried the code below:
Private Sub EnableEdit(strFieldname As String, Optional bUseRed As Boolean = False)
Me.Controls(strFieldname).Enabled = True
Me.Controls(strFieldname).Locked = False
If Not(TypeOf (Me.Controls(strFieldname)) Is CheckBox) Then
Me.Controls(strFieldname).BackStyle = 1
If bUseRed Then
Me.Controls(strFieldname).ForeColor = vbRed
Else
Me.Controls(strFieldname).ForeColor = vbBlack
End If
End If
End Sub
However
If Not(TypeOf (Me.Controls(strFieldname)) Is CheckBox) Then
is not syntactically correct. TypeOf expects an object and Me.Controls(strFieldname) is the control itself.
I tried alternative ways for Me.Controls(strFieldname).
https://learn.microsoft.com/en-us/dotnet/visual-basic/programming-guide/language-features/early-late-binding/determining-object-type
If you're using standard Access controls, the easiest way is just to access the ControlType property
If Not Me.Controls(strFieldname).ControlType = acCheckbox Then
For special controls, TypeOf can be beneficial. You need to specify the class, which is likely Access.Checkbox (msforms.Checkbox can be used in Access as well but is very unusual).
If Not TypeOf Me.Controls(strFieldname) Is Access.Checkbox Then
The main source of your error, by the way, is the excessive use of parentheses. If you surround an object with parentheses, you get its default property:
Me.Controls("MyCheckbox") 'A checkbox
(Me.Controls("MyCheckbox")) 'The value of a checkbox
The line If Not(TypeOf (Me.Controls(strFieldname)) Is CheckBox) Then has a problem:
The correct syntax would be:
If Not TypeOf Me.Controls(strFieldname) Is CheckBox Then
I have a checkbox control that i need to hide if a Boolean value is false. I have tried using the Detail_Format event to no avail. i put the field value into another checkbox, then tried setting the visible property from the value in the checkbox, no dice. In the image below, the rightmost checkbox is showing the value of the field that determines if the checkbox to the left of it should be shown. I have the following code
Private Sub Detail_Format(Cancel As Integer, FormatCount As Integer)
If Me.chkRequireverify = True Then
Me.chkVerified.Visible = True
Else
Me.chkVerified.Visible = False
End If
'Me.chkVerified.Visible = Me.chkRequireverify
End Sub
when i tried using the Detail_Paint event, it errored out telling me that i cant change the visible property in this event.
Your code looks to be correct and could be shortened to simply:
Private Sub Detail_Format(Cancel As Integer, FormatCount As Integer)
Me.chkVerified.Visible = Me.chkRequireverify
End Sub
However, I believe the event handler for the OnFormat event will only be evaluated when viewing the report in Print Preview view, rather than in Report view.
Whilst the OnPaint event fires in Report view, you cannot modify certain properties after the report has been formatted, the Visible property being one such property, along with the Height & Width properties (and so you also cannot shrink the checkboxes to zero size).
It's been a while since I've used Access and VBA, but I believe what you're missing is .Value after the checkbox name in the if clause.
Try this : If Me.chkRequireverify.Value = True
GD All,
I've looking around for a solution to my below challenge.
I have got a form with an unbound datagridview, the dg has one added column that allows user to select a method to be used.
The state of the event is stored in a database and after re-opening the form the code checks if the event is in an 'open' state, if so it compares the previously selected method with the methods in the datagrid and should set the previously activated method to be the 'selected' method.
Yet I can't seem to get this to work unfortunately...
The below code loops through the methods in the dg and compares the values, if it meets the methodID it should set the value to 'True' or to the TrueValue anyway.
This is initialized if the database check returns true and after full initialisation of the form, where session.methodID is a field in the returned LINQ query.
For Each r As DataGridViewRow In dgMethods.Rows
If r.Cells(1).Value = session.methodID Then
Dim c As DataGridViewCheckBoxCell = r.Cells(0)
c.Value = c.TrueValue
End If
Next
Unfortunately, this doesn't set the checkbox to 'Checked'.
The loop runs and evaluates the comparison between r.Cells(1).Value and session.methodID correct and triggers correctly.
The interesting thing is if I do a similar loop after the 'CellContentClick' event it does do exactly what is expected. (the example below sets all checkbox values to checked)
Private Sub dgMethods_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) Handles dgMethods.CellContentClick
'Only single selection allowed, so clear table before submitting new selection
For Each r As DataGridViewRow In dgMethods.Rows
Dim c As DataGridViewCheckBoxCell = r.Cells(0)
c.Value = c.TrueValue
Next
dgMethods.CommitEdit(DataGridViewDataErrorContexts.Commit)
End Sub
So, apparently there is a difference in the state between just calling the loop on the dgMethods and when the dgMethods.CellContentClick event has triggered, yet I do not know which one ?
There are many many post on trying to set the CheckBox column yet I have not been able to get any of them working.
Anybody have any idea ?
I would appreciate your suggestions ?
I was not sure of being undestand your question... but there's s simple way to check and change the state of a chechbox cell in a datagridview:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
For Each dr As DataGridViewRow In DataGridView1.Rows
If CBool(dr.Cells(0).Value) = True Then dr.Cells(0).Value = False : Continue For
If CBool(dr.Cells(0).Value) = False Then dr.Cells(0).Value = True
Next
End Sub
In this example, when you click this button for each row in the datagridview, checks the checkboxcell and set the value to FALSE or TRUE depending of his value.
Hope this helps you.
And let me one more tip. If you get acces to the cells for his name instead of his index use his name, it should helps you avoiding troubles ;)
GD All,
After searching further I came across the following interesting behaviour.
The method selection process is part of a form called 'frmAddEvent', the frmAddEvent form is called from a main form using below routine.
The new form instance is created and afterwards filled using a public sub in the form class called InitializeForm() which uses a GUID parameter to retrieve corresponding data to set the form fields.
If Not (isOpened(rsTankName.unqID)) Then
Dim newForm As New frmAddEvent() '(rsTankName)
newForm.InitializeForm(rsTankName)
newForm.Show()
Else
End If
The initialization sub queries several datatables and sets the corresponding fields in the new form instance correctly if applicable.
Part of that setting is the method selection in the dgMethods datagridview.
It would appear that the sequence in which you call the form makes all the difference as the below code works perfectly:
If Not (isOpened(rsTankName.unqID)) Then
Dim newForm As New frmAddEvent() '(rsTankName)
newForm.Show()
newForm.InitializeForm(rsTankName)
Else
End If
So calling the newForm.InitializeForm(rsTankName)after the newForm.Show event allows the datagridview to set the CheckBoxColumn correctly.
Likely because the actual CheckBox itself is only actually generated upon the Show command, despite the fact that it is 'available' as a cell with DataGridViewCheckBoxColumn properties in the datagrid, directly after the New frmAddEvent has created the new form instance. The actual CheckBox and its corresponding CheckedState is not created before the newForm.Show event is called. It would appear that the when the CheckBox is created for display (during the newForm.Show event) there is no comparison made to its actual value.
So, in order to set the Checkbox column on initiating a new form you have to call the Show event prior to setting the DataGridViewCheckBoxColumn values otherwise the CheckBox will not show it as 'Checked'.
I want iterate on GroupBox controls and check if the CheckBox are Checked or not. Actually I'm stuck on this:
For Each c In User.GroupBox3.Controls
If c.GetType.Name = "CheckBox" Then
If c.Checked = True ..?
End If
Next
How you can see I can't access to .Checked property, someone know how can I figure out?
Its about Types. CheckBox is a Type, which inherits from Control which is another Type. Since a ControlsCollection holds the items as Control, you have to cast to the specific Type in order to access the more specific properties and methods:
Long Form:
For Each c As Control In TabPage1.Controls
' check if it is the Type we are looking for
If TypeOf c Is CheckBox Then
' convert to desired type, do something
CType(c, CheckBox).Checked = True
End If
Next
CType converts/casts from Control to CheckBox.
Short Form:
For Each c As CheckBox In TabPage1.Controls.OfType(Of CheckBox)()
c.Checked = True
Next
This version filters to a given Type so the cast isnt needed.
I'm trying to assign text from "comp" in the form "home" to a textbox with the name "d1" in the form "home".
but this needs to be done with a counter in the form "home".
The code is in a module.
What I've tried=
home.controls("d" & home.counter).text = home.comp.text
I keep getting an error:
use the new keyword to create an object instance ==> the textbox exists in the form
check to determine if the object is null before calling the method ==> the textbox is empty
get general help for this exception
You could use Controls.Find:
Dim controls = home.Controls.Find("d" & home.counter, True)
If controls.Length > 0 Then
Dim txt = TryCast(controls(0), TextBoxBase)
If txt IsNot Nothing Then
txt.Text = home.comp.text
End If
End If
However, normally i would not use this approach since it's error-prone. Why don't you provide a public property in the Home-form that you can access? This property would get/set the TextBox' Text.
For example:
Public Property HomeCompText As String
Get
Return txtHomeComp.Text
End Get
Set(value As String)
txtHomeComp.Text = value
End Set
End Property
Now you can use this clear, safe and maintainable code:
home.HomeCompText = home.comp.text
You could even change the underlying control.