Q142885: How to Add the Data Environment to a Form Programmatically

Article: Q142885
Product(s): Microsoft FoxPro
Version(s): 3.00 3.00b
Operating System(s): 
Keyword(s): kbcode kbvfp300 kbvfp300b kbvfp600
Last Modified: 09-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 6.0 
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SUMMARY
=======

When a form is created using the Form Designer, a DataEnvironment object is
automatically added to the form. To simulate this behavior in a programmatically
created form, a DataEnvironment property must be declared for the form. Then a
pointer to a DataEnvironment object may be stored in the form's DataEnvironment
property.

MORE INFORMATION
================

1. Create a new program and type the following code:

     oform1=CREATEOBJECT("Myform")  && Instantiate the form
     oform1.SHOW(0)
     oform1.refresh
     READ EVENTS
     RETURN

     DEFINE CLASS Data1 AS dataenvironment   && DataEnvironment Class
       Name = "Dataenvironment"
       ADD OBJECT "Cursor1" AS MyCursor      && ADD OBJECT for each
     ENDDEFINE                               && cursor in dataenvironment

     DEFINE CLASS MyCursor AS cursor         && Cursor Class
       Alias = "customer"
       Database = "C:\vfp\samples\data\testdata.dbc"
       CursorSource = "customer"
       Name = "Cursor1"
     ENDDEFINE

     DEFINE CLASS Myform AS form
       Top = 0
       Left = 0
       Height = 386
       Width = 587
       DoCreate = .T.
       Caption = "Form1"
       Name = "FORM1"
       DataEnvironment=""                && DataEnvironment is a property
                                         && of the form.
       PROCEDURE Destroy
         WAIT WINDOW PROGRAM() TIMEOUT 2
         THISFORM.DATAENVIRONMENT.CLOSETABLES  && Close tables at the end
       ENDPROC                                 && of destroy procedure.

       PROCEDURE Unload
         CLEAR EVENTS
       ENDPROC

       PROCEDURE Load
         * The DataEnvironment is instantiated and the form property
         * DataEnvironment references the object. The DataEnvironment
         * is never actually added to the form. THISFORM.DATAENVIRONMENT
         * is just a pointer to the DataEnvironment object.

         THISFORM.DATAENVIRONMENT=CREATEOBJECT("Data1")

         * Open the tables at the beginning of the LOAD.
         THISFORM.DATAENVIRONMENT.OPENTABLES

         WAIT WINDOW PROGRAM() TIMEOUT 2
       ENDPROC
     ENDDEFINE

2. Open the Debug window.

3. Type the following on the left side of the debug window

     _SCREEN.ACTIVEFORM.DATAENVIRONMENT.NAME

4. Run the program created in step 1.

5. Note that the debug window correctly displays Dataenvironment as the value of
  _SCREEN.ACTIVEFORM.DATAENVIRONMENT.NAME

Additional query words: VFoxWin

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Keywords          : kbcode kbvfp300 kbvfp300b kbvfp600 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b kbVFP600
Version           : 3.00 3.00b

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