ACC97: Cannot View Class Module in a Referenced Database Library

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Microsoft Access 7.0 and 97 both support calling functions from an external database by creating a Visual Basic for Applications reference. This allows you to use the Object Browser to view functions marked as Public in a referenced database, and call the code from within the current database.

The following example creates a class object in a referenced database to demonstrate how to call functions in a class module of a referenced database, and to illustrate how the reference appears in the Microsoft Access 97 Object Browser.

Create the Reference Database

1. Create a new database called ClassTestRef.mdb.
2. On the Insert menu, click Class Module.
3. Save the class module as clsTest.
4. Select Class in the Object box of the module window. "Initialize" is automatically selected in the Procedure box of the module window.
5. Type the following procedure for the Initialize event:

         Private Sub Class_Initialize()
            On Local Error GoTo Class_Initialize_Err
            Dim Msg As String
            MsgBox "Class Initialized", vbInformation, "Class Example"
         Class_Initialize_End:
            Exit Sub
         Class_Initialize_Err:
            Msg = "Error #: " & Format$(Err.Number) & vbCrLf
            Msg = Msg & Err.Description
            Err.Raise vbObjectError, "clsTest.Initialize (Private)", Msg
            Resume Class_Initialize_End
         End Sub
   						

6. Type the following public procedure:

         Public Function CallClass()
            MsgBox "clsTest.CallClass method", _
                    vbInformation, "Class Example"
         End Function

7. Save and close the clsTest class module.
8. Create a new standard module by clicking Module on the Insert menu.
9. Type the following line in the Declarations section:

         Public cls As New clsTest

10. Save the module as modTest and close it.
11. Close the ClassTestRef.mdb database.

Create the Front-End Database

1. Create a new database called ClassTestFront.mdb.
2. Create a new standard module by clicking Module on the Insert menu, and then save the module as Module1.
3. On the Tools menu, click References.
4. In the References dialog box, click Browse.
5. In the Add Reference dialog box, select Microsoft Access Databases (*.mdb) in the File name box, and then select the ClassTestRef.mdb file. Click OK.
6. Note the new reference to ClassTestRef in the References dialog box, and then click OK.
7. Type the following procedure in the open module. This procedure calls the public CallClass function of the clsTest class module in the ClassTestRef database:

          Public Function TestClass() As Boolean
             cls.CallClass
             TestClass = True
          End Function

8. To test this function, type the following line in the Debug window, and then press ENTER.

   ? TestClass()

   Note that you receive two message boxes; the first one displays the text "Class Initialized," and the second one displays the text "clsTest.CallClass method."
9. Open Module1 in Design view.
10. On the View menu, click Object Browser.
11. Select ClassTestRef in the Project/Library box. Note that only modTest is visible in the Classes box, and that you can see the public variable cls that it contains; the class module clsTest is not visible in the Object Browser.