Passing strings between event procedures on form?

[caubetiep1337]

Hey guys,



I am just freshly starting out with Access and VBA coding. I am using a Form and trying to pass a variable from one event sub to another. But it keeps giving me errors: "Procedure declaration does not match description of event or procedure having the same name".

A snippet of my code is:

 Option Compare Database
Public Sub Form_Load()
Dim Fsobj As New FileSystemObject
Sub RosterChk_Click(Fsobj)
If FSobj.FileExists("C:\Users\U460809\Desktop\Import\roster.csv") = False Then
MsgBox "File Does not exists. Please download the extract."
RosterChk = False
End If

Any idea how to get around this? And if it's not possible, can someone explain why? Cause the variable can be referred across subs in a regular Module, right? Thanks!

-Dat

[orange]

What exactly, in plain English, are you trying to do?

[ItsMe]

Aside from the fact an explanation of what it is you trying to accomplish would be helpful, you have some syntax issues.

Public Sub Form_Load()
Dim Fsobj As New FileSystemObject
Sub RosterChk_Click(Fsobj)

You merged to procedures together. So you have the beginning of two subs merged together and no End Sub lines, termination lines.

[caubetiep1337]

Oh my bad, that was a mistake when copying over parts of the code. In short, I have a Form with checkboxes and a button. Based on what boxes are checked, some data will be imported after the button is clicked. What I want, though, is that upon clicking the checkbox, I want to check whether the file exists or not.

Public Sub Form_Load()
Dim Fsobj As New FileSystemObject
Dim Roster, FileLoc as string
FileLoc = "C:\Users\U460809\Desktop\Import\"
Roster = "Roster.csv"
End Sub

Private Sub UpdateBtn_Click()
'import data, saved in different module
Call Import_Roster
End Sub

Private Sub RosterChk_Click(Fsobj, FileLoc, Roster)
'load the strings here
If FSobj.FileExists(FileLoc & Roster)= False Then
MsgBox "File Does not exist. Please download the extract."
RosterChk = False
End If

[ItsMe]

So, what is happening is that you are declaring and instantiating the FileSystemObject in the On Load event. When this OnLoad event completes, at the End Sub line, the object is no longer in scope and is not anything, any longer.

The same goes for the string variables you declared. After the End Sub line, your computer has no reference to them.

One thing you can do is make declarations in the Module's Header. This way, the variables are available everywhere within the Module. One thing to make note of, you cannot use the New keyword when declaring a complex data type in the Module's Header. In other words, you cannot instantiate the Object there. You are not able to instantiate objects or make assignments to variables in the header.

So you would need to do something like ...

Option Compare Database

Dim FSobj As FileSystemObject
Dim Roster, FileLoc As String

Private Sub Command0_Click()

'load the strings here
If FSobj.FileExists(FileLoc & Roster) = False Then
    MsgBox "File Does not exist. Please download the extract."
'    RosterChk = False
End If

End Sub

Private Sub Form_Load()

Set FSobj = CreateObject("Scripting.FileSystemObject")  'instantiate here or in another procedure
FileLoc = "C:\Users\U460809\Desktop\Import\"    'assign values to variables here or in another procedure
Roster = "Roster.csv"

End Sub

Also, I am not sure what your intentions are with RosterChk = False (so I commented that out). Seems you should have another variable declared as type Boolean.

[caubetiep1337]

Thank you! Is there a way for me to reference those variables like Roster, As_Is, As_was in different modules, too? Outside the Form module?

[ItsMe]

You can declare variables in a way that they are available on the Public side. However, simple data types, like String, Long, Int, etc. will always be Private when decalred in a Form or Report's module. The simplest is to place them in a Standard Module and declare them as Public.

Doing the following in a Form's Module will be Private to that module.
Public strValue As String
or
Dim strValue As String

And, as you learned earlier, the scope, or life, of that variable depends on where, within the module, you place the declaration. The take away here is the above declaration is Private and not available on the Public side.

If you want a variable to be avaialbe on the Public side, you need to place it in a Standard Module or a Custom Class. A simple explanation/example is to place the following in the header area of a Standard module. In other words, not in a function or other procedure, like a Sub-Procedure.
Public strValue As String

Declaring your variable as Public and in a Standard Module causes the variable to be available on the Public side. In other words, available to any other Module. There are rules and exceptions regarding some objects gaining access to Public variables, like tables and queries.

One last thing to remember about using variables that are simple data types, they are volatile. In other words, if there is an error/exception, the reference will be erased.

[caubetiep1337]

But what about assigning a value to the variable that will be saved and used across modules? Something like this?

 
'Form Module
Option Compare Database
Public StrName As String
StrName = "test"

Sub blabla()
'...
End Sub

And if I go to another module and write let's say

 
Module1


MsgBox StrName

will it say "test" or will it be blank?

Thanks!

[ItsMe]

I am going to have to edit my other post. I made a mistake. You cannot access simple data types on the Public side when they are declared in a form's module. You can access a procedure, but not a String Variable.

So, what you will have to do is use a Standard Module for your ...
Public StrName As String

And the other thing you need to pay attention to is where you do your assignment.
StrName = "test"

The assignment needs to be done in a procedure. So you could do it in a Form's load event or a click event or a function, etc.

[ssanfu]

And one more thing. This statement

Dim Roster, FileLoc As String

declares "Roster" as a variant type and FileLoc As String.

In VBa, to have both declared as strings, you must explicitly declare the variables

Dim Roster As String, FileLoc As String

[caubetiep1337]

@ssanfu

thanks!I initially learned VB with Visual Studio so it's good to know there are syntax differences!

@ItsMe

thanks for clarifying and explaining the concepts!

Cheers!

[ItsMe]

Also, you do not have to use a Standard Module. You can use the existing Classes associated with forms and also create your own classes. Like I mentioned, you can create procedures in a Form's module and make these available on the public side.

For instance, you can make a click event Public and call the click event from another form. Also, you can create constructers. Here is an example of a procedure to create a property field of a form's class module.

Public Property Get MyPractice() As String
    MyPractice = p_strPractive
End Property

So you could declare p_strPractive in the Module's header ...

Dim p_strPractive as string

And then assign the value to the private variable in the same form's load event or a click event.

p_strPractive = "Hello World"

Then, from another form, you can use the full namespace of the MyPractice field from another form.

 MsgBox Forms!FirstFormName.MyPractice

[John_G]

Hi -

Referring back to your first post, about the error message.

If this line:

Sub RosterChk_Click(Fsobj)

is the first line of the On_click event procedure of a button called RosterChk, that is what is causing the error. The On Click event procedure does not have any parameters, and you will get that error if you try to use any.

[caubetiep1337]

Thanks guys, I made it work so that I can call in variables to the click procedure! I do have another thing. I want to write a code that's based on whether a checkbox is checked or not, but in a standard module (not in the form module) so that in the actual form module, I can just call the sub in the button event. E.g.

 
Module1
Sub Example()
If Chkbox = True Then
...
End if
End Sub

In the Form Module

Form1
Private Sub Btn_Click()
Call Example
End Sub

So far, in the standard module, it doesn't read whether checkbox has been checked or not. I want to AVOID going into the Form module and write something like this:

Form1
Private Sub Btn_Click()
If Chkbox = True Then
Call Example
End if
End Sub

Cause I have multiple things that I want to activate with the button and just want to have something like:

Form1
Private Sub Btn_Click()
Call Example
Call Example2
Call Example3
...

End Sub

[John_G]

It's easily done. All you need to do is pass the reference to the form as an argument to the sub.

So, in your standard module1 you would have:

Sub Example(frm as Form)
If frm.Chkbox = True Then
...
End if
End Sub

and in the form code, you would have:

Private Sub Btn_Click()
Call Example Me
End Sub

or

Private Sub Btn_Click()
Call Example Me
Call Example2 Me
Call Example3 Me
...

End Sub