How to Load Windows Form From Data Base
Some times we want to save the form name in data base and load form using that saved name. How would we achieve this task? In 2005 there is Name space called “System.Reflection” This name space support dynamically creating types.
Private Function LoadFormFromDataBase(ByVal FormName As String) As Object
1 Dim oRetForm As Object = Nothing
2
3 Dim oType As Type =
4 Assembly.GetExecutingAssembly().GetType("MyProject." & FormName)
5
6 If oType IsNot Nothing Then
7 oRetForm = Activator.CreateInstance(oType)
8 End If
9
10 Return oRetForm
11
End Function
This function has one argument it is a Form name. In line 3 and 5 you can see our form name (the argument we passed to load the form) dynamically assembling in our memory. For this instance there is on big important thing, that was your Project what is the Project your form containing. Also another very, very important thing is “.” after your Project Name. That is the separator acting between Project name and the Form name.
So we now we are going to implement that instance in our memory (else you can create it remotely) . This task doing Activator class using CreateInstance method in line 7. This CreateInstance method 14 arguments but for this task we just passing object type.
So now you have form in your object type variable (oRetForm),
Using this method you can load other controls as well.
Review
Ok I got few comments of my friends, first I would like to thanks all of your comments. Yes actually this windows form not saved in your data base actually data base contain your form name (Keep it mind not a form text). So lets see why we want this kind of things.
ok you have tree node, dynamically load from data base.(Node name, root, etc) so when you click that node you have to open a form. for that you have two option
one is get a node name and load form, for that you have to hard code your form name like this
Private Sub treMain_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles treMain.AfterSelect
With e.Node
If .Name = "A" Then
Dim OfrmA As New frmA
frmA.Show()
ElseIf .Name = "B" Then
Dim OfrmB As New frmB
OfrmB.Show()
ElseIf .Name = "C" Then
Dim OfrmC As New frmC
OfrmC.Show()
ElseIf .Name = "D" Then
Dim OfrmD As New frmD
OfrmD.Show()
ElseIf .Name = "E" Then
Dim OfrmE As New frmE
OfrmE.Show()
ElseIf .Name = "F" Then
Dim OfrmF As New frmF
OfrmF.Show()
ElseIf .Name = "G" Then
Dim OfrmG As New frmG
OfrmF.Show()
End If
End With
End Sub
other way is in your Node Table you have to create extra column for contain a form name for that node. so when you loading that tree node you can add form name for the tree node name. so now you have your form names in your tree view's node names.
now just use this code
Private Sub treMain_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles treMain.AfterSelect
Dim frmUnLoad As New Form
frmLoad = LoadFormFromDataBase(e.Node.Name)
End Sub
Private Function LoadFormFromDataBase(ByVal objectName As String) As Object
Dim returnObj As Object = Nothing
Dim type As Type = Assembly.GetExecutingAssembly().GetType("UserInterface." & objectName)
If type IsNot Nothing Then
returnObj = Activator.CreateInstance(type)
End If
Return returnObj
End Function
That’s it. Now you can load your form when you clicking the node.
So do you want edit your code if you want add new form and add new node for the solution, no need , create a form add to your solution and add a record to your node table with form name that it.
Which one is better solution? Decision is on your side
