How to Use Data Sessions in a Toolbar to Show Changes

• Microsoft Visual FoxPro for Windows, version 3.0

SUMMARY

This article describes two methods you can use to use data sessions in a toolbar to reflect changes among multiple instances of both parent and child forms. Multiple instances of both parent and child forms can be reflected in the toolbar and menu as focus shifts from one form to another.

MORE INFORMATION

The main reason the DataSessionID property is read/write is so you can set non-databound forms or toolbars to link up with another private data session's form, formset, or toolbar. The toolbar can query the _Screen.Activeform property to determine which form is currently active. Each form can have a property identifying whether it's in the process of an edit or not.

Method One

Make sure the toolbox class has DataSessions=2. Then within a method of a toolbox subclass, try the following logic to manipulate data of the active form:

   Thisform.DataSessionID=_screen.ActiveForm.DataSessionID

Method Two

Use a timer to determine the status of the active form, enabling or disabling controls on the toolbar as appropriate. In the toolbar's INIT event, add a Timer to the screen as follows:

   _Screen.AddObject("ToolBartimer" MyTimerClass)

   MyToolBar.DataSessionID = IIF(TYPE("_Screen.ActiveForm") == "O",;
      _Screen.ActiveForm.DataSessionID,1)

IF ( ("2" $ GETFLDSTATE(-1)) OR ;

     ("3" $ GETFLDSTATE(-1)) OR ;
     ("4" $ GETFLDSTATE(-1)) )
   MyToolBar.cmdNewButton.Enabled  = .F.
   MyToolBar.cmdSaveButton.Enabled = .T.
   MyToolBar.cmdUndoButton.Enabled = .T.

   MyToolBar.cmdNewButton.Enabled  = .T.
   MyToolBar.cmdSaveButton.Enabled = .F.
   MyToolBar.cmdUndoButton.Enabled = .F.

NOTE: Make sure your toolbar does not contain any bound controls. Changing the datasession of a bound form is not recommended.