I wanted to test if I could get this to work: I have two textboxes with IDs Textbox1 and Textbox2. I enter the name of a variable I have stored in my program in Textbox1 and then I enter any value in Textbox2. After clicking on a confirm button I want to have the value of the variable name that I've written in Textbox1 changed to the value I wrote in Textbox2.
Something like this (in pseudocode)
GetVariable(Textbox1.Text) = Textbox2.Text
Is there an easy way to get this done or will I be forced to create other type of functions to get around this kind of problem?
Yes, you can do this using reflection.
dim property = this.GetType().GetProperty(Textbox1.Text)
property.SetValue(this, Textbox2.Text)
This will not work on local variable, but it will work on properties.
Of course the better way would be to just use a Dictionary(of string, string) instead of loose variable. Then you can just write myValues(Textbox1.Text) = Textbox2.Text.
Another example of using Reflection. This will work on Fields or Properties. They can be Public or Private, and you don't have to exactly match the Case:
Try
Dim FI As System.Reflection.FieldInfo = Me.GetType.GetField(TextBox1.Text, Reflection.BindingFlags.IgnoreCase Or Reflection.BindingFlags.Instance Or Reflection.BindingFlags.Public Or Reflection.BindingFlags.NonPublic)
If Not IsNothing(FI) Then
FI.SetValue(Me, TextBox2.Text)
Else
Dim PI As System.Reflection.PropertyInfo = Me.GetType.GetProperty(TextBox1.Text, Reflection.BindingFlags.IgnoreCase Or Reflection.BindingFlags.Instance Or Reflection.BindingFlags.Public Or Reflection.BindingFlags.NonPublic)
If Not IsNothing(PI) Then
PI.SetValue(Me, TextBox2.Text)
Else
MessageBox.Show(TextBox1.Text, "Field or Property not found!")
End If
End If
Catch ex As Exception
MessageBox.Show(ex.Message, "Unable to Set Value")
End Try
Or you can also create a label control at runtime with the value of TextBox1 Text and assign a value according to the Text of TextBox2. This label will be invisible:
Dim MyNewObject As Control
MyNewObject = New Label
MyNewObject.Name = Textbox1.Text
MyNewObject.Text = Textbox2.Text
MyNewObject.Visible = False
Me.Controls.Add(MyNewObject)
And you can use it as a variable in any part of the form. Example to show the value should be as follows:
MsgBox(Me.Controls(Textbox1.Text).Text)
Related
I have a code to import csv to auto generated text box which was a part of my previous app. However I had to re do the whole script which involves importing csv to multiple existing textbox.
Below is my old code which worked like a charm but in this code my textbox were getting auto generated based on the numbers of value present in my csv.
Dim T(100) As TextBox
Using ofd As New OpenFileDialog()
If ofd.ShowDialog() = DialogResult.OK Then
TextBox1.Text = (ofd.FileName)
End If
Using MyReader As New Microsoft.VisualBasic.
FileIO.TextFieldParser(TextBox1.Text)
MyReader.TextFieldType = FileIO.FieldType.Delimited
MyReader.SetDelimiters(",")
Dim numer As Integer
Dim currentRow As String()
numer = 1
While Not MyReader.EndOfData
Try
currentRow = MyReader.ReadFields()
Dim currentField As String
For Each currentField In currentRow
If (currentField IsNot "") Then
Dim myTB As New TextBox
T(numer) = myTB
myTB.Text = currentField
myTB.Visible = True
myTB.Location = New Point(550, 92 + (numer * 28))
myTB.Name = "ADBox" + numer.ToString
myTB.ReadOnly = True
Me.Controls.Add(myTB)
numer += 1
End If
Next
Catch ex As Microsoft.VisualBasic.
FileIO.MalformedLineException
MsgBox("Line " & ex.Message &
"is not valid and will be skipped.")
End Try
End While
End Using
End Using
But that created a lot of issue in my app hence I had to load the values on an existing textboxes(Multiple) but I am somehow not able to.
Edit1:
*** The code above creates a textbox and adds my csv values to it and what I am looking for is inject csv to existing textbox which I have created and not automatically generated text box.
For Example my code creates text box called ADUser1,2,3,4 and enters all the value but my following code which will create a textfile by fetching the values from the text box is not working because when I declare
My.Computer.FileSystem.WriteAllText(aduser1, ADBox1.Text, True)
it says it doesn't exists because when a form loads it never created such textboxes. This is the challenge I am facing
Any help will be a great value
Thanks
I agree that this is a very awkward design and should be redone, but for the purpose of answering your question...
The reason your code here: My.Computer.FileSystem.WriteAllText(aduser1, ADBox1.Text, True) doesn't find ADBox1 is that it is not created and referenced like an object you drag on to the form. It could be, by the way, but that is more work than dragging and naming 100+ text boxes on your form. Nuts. Creating the textboxes in code is better.
If you "manually" add one textbox to a form, then examine the designer-generated code for the form you will see that it created a textbox for you. You would find something similar to Friend WithEvents ADBox1 As System.Windows.Forms.TextBox. This is the reason you can reference the textbox in your form code. There is no magic here and you are technically doing the same thing in your code, here:
Dim T(100) As TextBox
...
Dim myTB As New TextBox
T(numer) = myTB
You can use the reference T(n) to refer to any of your textboxes. It is not clear where the WriteAllText function is but you may need to be sure Dim T(100) As TextBox is a form global, then change the WriteAllText line like this to get at ADBox1:
My.Computer.FileSystem.WriteAllText(aduser1, T(1).Text, True)
I'm working on a project that requires I iterate through a list of controls on a tabpage to find all of the checkboxes. Then depending on the state of the box (checked or unchecked) select individual variables (filenames) to then perform either a batch rename or delete of files on the filesystem (cb.checked = perform action).
I have managed to create the "for each" for the iteration of the controls (thanks google) but I'm struggling to figure out how to pick the variables. They are all named differently, obviously, as are the checkboxes. Also the checkboxes are statically assigned to the form/tabpage. Here's what I have at the moment.
Public Sub delBut_code(ByRef fname As String)
If (Sanity = 1) Then
For Each cb As Control In Form1.Controls
If TypeOf cb Is CheckBox AndAlso DirectCast(cb,
CheckBox).Checked Then
If My.Computer.FileSystem.FileExists(fname) Then
My.Computer.FileSystem.DeleteFile(fname)
End If
End If
Next
MessageBox.Show("All Actions Completed Successfully")
Else
MessageBox.Show("Please select a File To Delete")
End If
End Sub
and here is an example of some of the variables:
Dim castle As String = selPath & "\zm_castle_loadingmovie.txt"
Dim factory As String = selPath &
"\zm_factory_load_factoryloadingmovie.txt"
Dim island As String = selPath & "\zm_island_loadingmovie.txt"
N.B selpath collects a user entered folder path and can be ignored here
I would really appreciate any pointers.
First, you can do much better with the loop:
Public Sub delBut_code(ByRef fname As String)
If Sanity <> 1 Then
MessageBox.Show("Please select a File To Delete")
Exit Sub
End If
Dim checked = Form1.Controls.OfType(Of CheckBox)().Where(Function(c) c.Checked)
For Each box As CheckBox in checked
Try
'A file not existing is only one reason among many this could fail,
' so it needs to be in a Try/Catch block.
' And once you're using a Try/Catch block anyway,
' the FileExists() check becomes a slow and unnecessary extra trip to the disk.
My.Computer.FileSystem.DeleteFile(fname)
Catch
'Do something here to let the user know it failed for this file
End Try
Next
MessageBox.Show("All Actions Completed")
End Sub
But now you need to know how have the right value in that fname variable. There's not enough information in the question for us to fully answer this, but we can give some suggestions. There a number of ways you could do this:
Set the Tag property in the Checkboxes when you build the string variables. Then fname becomes DirectCast(box.Tag, String).
Inherit a custom control from CheckBox to use instead of a normal Checkbox that has an additional String property for the file name. Set this property when you build the string variables.
Name your string variables in a way that you can derive the string variable name from the CheckBox variable name, and then use a Switch to pick the right string variable from each box.Name.
Keep a Dictionary(Of CheckBox, String) that maps the Checkboxes to the right string values.
But without knowing more context of the application, I hesitate to recommend any of these over the others as best for your situation.
Textbox.text I want to access. And I want it user-configurable before I want to access the altered text.
Dim qbox As New TextBox
qbox.Size = New Size(20, 20)
qbox.Location = New Point(90, 10)
qbox.Parent = addtocart
qbox.Name = "quarts"
qbox.Text = "ss"**
how I dynamically add it inside a series of other dynamic controls:
tile.Controls.Add(addtocart)
flpp.Controls.Add(tile)
tile.Controls.Add(plabel)
tile.Controls.Add(nlabel)
addtocart.Controls.Add(qbox)
How I tried to access it:
qb.Text = CType(Me.Controls("flpp").Controls("tile").Controls("addtocart").Controls("qbox"), TextBox).Text
I generated to textbox at runtime. Of course it's dynamic. I'm new to VB and I'm just experimenting a school project. I wanted the textbox text to be configurable and then access that configured value. I've been brain-cracking for days about this. when I run the thing, I "getObject reference not set to an instance of an object." under NullReferenceException was unhandled" something like this. I don't get it.
WinForms? If yes, and you want to find that control "by name", then use the Controls.Find() function:
Dim ctlName As String = "quarts"
Dim matches() As Control = Me.Controls.Find(ctlName, True)
If matches.Length > 0 AndAlso TypeOf matches(0) Is TextBox Then
Dim tb As TextBox = DirectCast(matches(0), TextBox)
' ... use "tb" somehow ...
Dim value As String = tb.Text
MessageBox.Show(value)
End If
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.
Please, can anyone help me with this problem:
I have a name(s) of control(s) in string format (str) and I want to set property (in code) of that controls using that string-name.
I try something like this but it doesn't work. Actually, I have a problem with expression. When I put exactly the name it works but when i use variable in string format it doesn't.
Dim str as String
str="k3"
Dim g As Image = CType(str, Image)
g.Source = New BitmapImage(New Uri("/APP;component/Icons/hero.png", UriKind.Relative))
This works:
Dim g As Image = CType(k3, Image)
While this does not:
Dim g As Image = CType(str, Image)
I think I understand what you are trying to do, to declare an object by a string...
Essentially for this to work you will need a custom function that returns the Object Type that you are seeking...
You will need to loop through each control and check the name of the control as a comparison, e.g. If oControl.Name.ToString = sString then Return oControl
Example
' A function to return a Control by the Control's name...
Public Function GetControlByName(ByVal oForm As Form, ByVal sName As String) As Control
Dim cReturn As New Control
Dim ctrl As Control
For Each ctrl In oForm.Controls
cReturn = ctrl
If ctrl.Name.ToString = sName Then
Return ctrl ' this is what we want!
End If
Next
Return cReturn
End Function
' Example Usage
Dim oButton As Button = GetControlByName(Me, "Button44")
If oButton.Name.ToString = "Button44" Then
MessageBox.Show("I have found your Button!")
Else
MessageBox.Show("Your button was NOT Found!")
End If
Obviously there is room for error with this function, because if sName is NOT found, then it will return the last ctrl found, therefore, you will need to ensure that the control you seek is indeed found, via the If statement as provided in the example above...
Furthermore, it may not loop through controls inside of containers, menus, etc, but I'm not sure on that, so you will need to check to ensure it's not having that problem...
(The Me in the statement will most likely be used more often than not, though Me could be the name of the form you are searching if you are running the code outside of the form you are searching the form with the function.)
FINALLY, to answer your question, you will need to change Control to Image, and Set CReturn as a New Image, and then use Return ctrl.BackgroundImage (etc) to return the image..