HOWTO: Synchronize Data Displayed on Two Different Forms

ID: Q193241

The information in this article applies to:
  • Microsoft Visual FoxPro for Macintosh, version 3.0b
  • Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a, 6.0

SUMMARY

In some circumstances, it is necessary to create two or more forms that are independent of each other while keeping the data displayed in the forms synchronized. This article demonstrates how to synchronize the data displayed on two independent forms.


MORE INFORMATION

In order to synchronize the data display between two or more independent forms, it is necessary to call the refresh method of the form(s) that contain the data that needs to be refreshed. The methods available for refreshing a form after moving a record pointer are to some extent dependent on how the form is being instantiated.

The following example illustrates use of the Refresh method between two forms:

  1. Create a form named TEST1 and change the Caption property to "Employee Form."


  2. Add the EMPLOYEE table from the \\SAMPLES\DATA directory to the form's DataEnvironment and set the ORDER to EMP_ID.


  3. Drag the following fields from the EMPLOYEE table to the form: 
    
      EMPLOYEE.EMP_ID
      EMPLOYEE.LAST_NAME
      EMPLOYEE.FIRST_NAME
      EMPLOYEE.TITLE


  4. Add the following code to the form's Init event: 
    
      DO FORM TEST2


  5. Create a form named TEST2 and change the Caption property to "Search Form." Add the EMPLOYEE table from the \\SAMPLES\DATA directory to the form's DataEnvironment and set the ORDER to EMP_ID. In the form's DataEnvironment and set the following values: 
    
      AutoCloseTables=.F.
      AutoOpenTables=.F.


  6. Add a list box control that has the following values to the form: 
    
      RowSourceType=6 - Fields
      RowSource=EMPLOYEE.EMP_ID


  7. Add the following code to the Click event of the list box control: 
    
      IF !EMPTY(THIS.VALUE)
         IF SEEK(RTRIM(THIS.VALUE))
            * Note that TEST1 is the name of the .SCX file created earlier
            test1.REFRESH
         ENDIF
      ENDIF


  8. Save the form.


  9. From the command line type "DO FORM TEST1" and use the form captioned "Search Form" to move the record pointer. After you click a value in the list box, the data in the "Employee Form" refreshes.


If the form is being instantiated from a class definition, refreshing the form becomes somewhat more problematic. In this case, the FORMS collection must be used to refresh the target form(s).

The following code illustrates use of the FORMS collection to refresh another form:

  1. Create a program file called Demo.prg that contains the following code: 
    
      * Begin Code
      PUBLIC ox
      ox=CREATEOBJECT('SYNCHED1')
      ox.SHOW

      DEFINE CLASS synched1 AS FORM
         TOP = 50
         LEFT = 162
         HEIGHT = 160
         WIDTH = 310
         DOCREATE = .T.
         CAPTION = "Employee Form"
         NAME = "Form1"
         AUTOCENTER=.T.

         ADD OBJECT lblemp_id AS LABEL WITH ;
            AUTOSIZE = .T., ;
            BACKSTYLE = 0, ;
            CAPTION = "Employee ID", ;
            LEFT = 11, ;
            TOP = 0, ;
            TABINDEX = 3, ;
            NAME = "lblEmp_id"

         ADD OBJECT lbllast_name AS LABEL WITH ;
            AUTOSIZE = .T., ;
            BACKSTYLE = 0, ;
            CAPTION = "Last Name", ;
            LEFT = 11, ;
            TOP = 36, ;
            TABINDEX = 5, ;
            NAME = "lblLast_name"

         ADD OBJECT lblfirst_name AS LABEL WITH ;
            AUTOSIZE = .T., ;
            BACKSTYLE = 0, ;
            CAPTION = "First Name", ;
            LEFT = 11, ;
            TOP = 72, ;
            TABINDEX = 7, ;
            NAME = "lblFirst_name"

         ADD OBJECT lbltitle AS LABEL WITH ;
            AUTOSIZE = .T., ;
            BACKSTYLE = 0, ;
            CAPTION = "Title", ;
            LEFT = 11, ;
            TOP = 108, ;
            TABINDEX = 9, ;
            NAME = "lblTitle"

         ADD OBJECT txtemp_id AS TEXTBOX WITH ;
            CONTROLSOURCE = "employee.emp_id", ;
            HEIGHT = 23, ;
            LEFT = 84, ;
            MAXLENGTH = 6, ;
            TABINDEX = 4, ;
            TOP = 0, ;
            WIDTH = 53, ;
            NAME = "txtEmp_id"

         ADD OBJECT txtlast_name AS TEXTBOX WITH ;
            CONTROLSOURCE = "employee.last_name", ;
            HEIGHT = 23, ;
            LEFT = 84, ;
            MAXLENGTH = 20, ;
            TABINDEX = 6, ;
            TOP = 36, ;
            WIDTH = 149, ;
            NAME = "txtLast_name"

         ADD OBJECT txtfirst_name AS TEXTBOX WITH ;
            CONTROLSOURCE = "employee.first_name", ;
            HEIGHT = 23, ;
            LEFT = 84, ;
            MAXLENGTH = 10, ;
            TABINDEX = 8, ;
            TOP = 72, ;
            WIDTH = 80, ;
            NAME = "txtFirst_name"

         ADD OBJECT txttitle AS TEXTBOX WITH ;
            CONTROLSOURCE = "employee.title", ;
            HEIGHT = 23, ;
            LEFT = 84, ;
            MAXLENGTH = 30, ;
            TABINDEX = 10, ;
            TOP = 108, ;
            WIDTH = 218, ;
            NAME = "txtTitle"

         PROCEDURE LOAD
            PUBLIC varval
            IF ATC("Visual FoxPro 06.",VERSION())>0
            USE Home(2)+"Employee.dbf"
            Else
            USE home()+"\samples\data\employee"
            ENDIF
            SET ORDER TO TAG emp_id
            GO TOP
            STORE SPACE(LEN(employee.emp_id)) TO m.varval
         ENDPROC

         PROCEDURE DESTROY
            FOR i=1 TO _SCREEN.FORMCOUNT
               * Look for the Search Form in the FORMS collection.
               IF _SCREEN.FORMS(i).CAPTION="Search Form"
                  * If the Search Form exists, release it
                  _SCREEN.FORMS(i).RELEASE
               ENDIF
            ENDFOR
            * Close the table.
            SELECT employee
            USE
         ENDPROC

         PROCEDURE INIT
            * Launch the Search Form.
            PUBLIC search
            search=CREATEOBJECT('SYNCHED2')
            search.SHOW
         ENDPROC
      ENDDEFINE

      DEFINE CLASS synched2 AS FORM
         TOP = 0
         LEFT = 0
         HEIGHT = 118
         WIDTH = 205
         DOCREATE = .T.
         CAPTION = "Search Form"
         NAME = "Form2"

         ADD OBJECT list1 AS LISTBOX WITH ;
            ROWSOURCETYPE = 0, ;
            HEIGHT = 96, ;
            LEFT = 24, ;
            TOP = 12, ;
            WIDTH = 145, ;
            NAME = "List1"

         PROCEDURE INIT
            THIS.list1.ROWSOURCETYPE=1
            IF USED('EMPLOYEE')
               SELECT employee
               currec=RECNO()
               GO TOP
               SCAN
                  * Load the list box with data from the table.
                  THIS.list1.ADDLISTITEM(employee.emp_id)
               ENDSCAN
               GOTO currec
            ENDIF
         ENDPROC

         PROCEDURE list1.CLICK
            IF !EMPTY(THIS.VALUE)
               SELECT employee
               IF SEEK(RTRIM(THIS.VALUE))
                  * Move the record pointer
                  FOR i=1 TO _SCREEN.FORMCOUNT
                     * Look for the Employee Form in the FORMS collection.
                     IF _SCREEN.FORMS(i).CAPTION="Employee Form"
                        * If the Employee Form exists, Refresh it
                        _SCREEN.FORMS(i).REFRESH
                     ENDIF
                  ENDFOR
               ENDIF
            ENDIF
         ENDPROC

         PROCEDURE DESTROY
            FOR i=1 TO _SCREEN.FORMCOUNT
               * Look for the Employee Form in the FORMS collection.
               IF _SCREEN.FORMS(i).CAPTION="Employee Form"
                  * If the Employee Form exists, release it
                  _SCREEN.FORMS(i).RELEASE
               ENDIF
            ENDFOR
         ENDPROC
      ENDDEFINE
      * End Code.


  2. From the command line type "DO DEMO" and use the form captioned "Search Form" to move the record pointer. After clicking a value in the list box, the data in the Employee Form refreshes.



REFERENCES

(c) Microsoft Corporation 1998. All Rights Reserved. Contributions by John Desch, Microsoft Corporation

Additional query words: kbVFp300 kbVFp500 kbVFp600 kbVFp500a kbContainer kbCtrl

Keywords :
Version : MACINTOSH:3.0b; WINDOWS:3.0,3.0b,5.0,5.0a,6.0
Platform : MACINTOSH WINDOWS
Issue type : kbhowto


Last Reviewed: August 5, 1999
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