Indirect reference a form name

Posted on 1999-01-27
Last Modified: 2010-05-03
I want to use a common routine to show and unload forms. The name of the next form to process is stored in a database. I save this name in a string variable. How can I later reference this name to show the form? The unload is easy - I simply walk the Forms collection until I find a matching name. But I can't figure out how to do something like "" (where nextForm contains the name of the form).
Question by:chucka

Expert Comment

ID: 1470922
Dim nextForm as form
set nextform = nameoftheform

Author Comment

ID: 1470923
No, that won't work. I had already tried it - gives a Type Mismatch. I did the following:

dim nextShow as form
set nextShow = rs("show") ' Contains the name of the next form

Author Comment

ID: 1470924
There must be a collection of Forms in the project (not the loaded forms collection). Perhaps I could walk that list and locate the form that way maybe, if I knew where to find it?? There has to be a way to reference a form through a variable rather than explicitly by it's name in code.


Expert Comment

ID: 1470925
The form instances are aded to the collection as they are created.  
I am not aware of anyway you can typecast the string in such a way that your set statement will work.
The only thing I could suggest is this...
Add a type filed to your table (or use your name field)
Then in your nextShow put in a case statement eg...
Select Case rs("show")
  Case "Form1"
    set nextShow = Form1

Author Comment

ID: 1470926
That would work and there's an easier way to do it, but that's what we are trying to get away from - that's the way it's being done now....... There are about 160 forms in this project! There are several Select Case structures in various modules to deal with all these forms and we want to simplify things.
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LVL 10

Expert Comment

ID: 1470927
You said the name of the next form in the process was stored in the database? In a table? Could you set up a recordset based on that table and then do one of these each time?

    strName = rs(0)
    Set nextForm = Forms(strName)

Would that work?



Author Comment

ID: 1470928
Nope - Type Mismatch - I tried something like that earlier. First, the form is not loaded so not in the Forms collection. Second, I think you ned to use an index, not a name to access the collection.
LVL 18

Expert Comment

ID: 1470929
I'm not at a machine where I can test this but how about trying:

dim nextShow as form
set nextShow = CreateObject(rs("show"))


Author Comment

ID: 1470930
Got "ActiveX component can't create object". I implemented your suggestion as :

    Dim nextSh As Form
    Set nextSh = CreateObject(nextShow)

Note: Nextshow was set previously to the name of the form.

Thanks for the help. I think this may not be possible (although it should). I'm out of town until Saturday from now. I'll check back on any other suggestions then. Thanks to all.

Accepted Solution

VBDesigns earned 200 total points
ID: 1470931
Thanks to Mike Dixon from Microsoft for this response:

You should be able to use Forms.Add, but it is broke. The bug has been isolated and fixed. The fix will not be available for several months, as it requires a service pack release for updating MSVBVM60.DLL. Please note that there is always a possibility that the bug could become "unfixed" or testing could reveal a need to change it back. (In this case, I highly doubt that will happen based on the reason behind the bug.) I have tested it against an internal build and it does work in the exe now.

In the mean time, the workaround mentioned in Q194912 will have to be used
if you need to ship the application or to run it as an exe. Below is another
code sample that may work better for you. Since each form is known by the
programmer when they add it to the project, all they need to do is add
another Case Statement to the LoadFormByString function for the new form:

Private Sub Command1_Click()
    Dim frm As Form
    Set frm = LoadFormByString("Form2")
    if frm is nothing then
        'Form was not loaded
    End If
End Sub

Public Function LoadFormByString(sFormName As String) As Form
    'Each time a new form is added to the project, add the code here:
    Select Case sFormName
        Case "Form2": Set LoadFormByString = New Form2
        Case "Form3": Set LoadFormByString = New Form3
        Case "Form4": Set LoadFormByString = New Form4
    End Select
End Function


Expert Comment

ID: 1470932
Use this:

(I'm commenting because I believe that VBDesigns' answer is bascially the same as a previuously rejected answer...)

Note that the return value of GetForm must be declared as a variant (or object) if it is a public procedure - VB won't let you return a Form from a public procedure.

Now you can say:


You'll get an Err 91 if the forms hasn't been loaded.

Public Function GetForm(FormName as String) As Variant

    Dim frm As Form
    For Each frm In Forms
        If frm.Name = FormName Then
            Set GetForm = frm
            Exit Function
        End If

End Function

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