Q315648: HOW TO: Use Custom Formatting with a Visual Basic 6.0 Data Grid
Article: Q315648
Product(s): Microsoft Visual Basic for Windows
Version(s): 6.0
Operating System(s):
Keyword(s): kbAudDeveloper kbHOWTOmaster
Last Modified: 22-MAR-2002
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The information in this article applies to:
- Microsoft Visual Basic Professional Edition for Windows, version 6.0
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0
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IN THIS TASK
------------
- SUMMARY
- Requirements
- Use the StdDataFormat Object
- Verify it Works
- Troubleshooting
- REFERENCES
SUMMARY
=======
Use this step-by-step guide to customize the formatting of data both before and
after a cell in a Data Grid is edited. The example in this article uses a text
field in which the characters are stored in uppercase, but which can be
displayed and edited in mixed-case on screen.
The Data Grid in Visual Basic 6.0 displays data from a database and allows user
editing. Transfers between the data grid and the underlying database are handled
automatically through ActiveX Data Objects (ADO). In some cases, the format of
the data on screen differs from the format of the data in the database, and
conversion is required.
Requirements
------------
The following items describe the recommended hardware, software, network
infrastructure, skills and knowledge and service packs you will need.
- You need a basic knowledge of Visual Basic programming to perform the
procedure in this article.
Use the StdDataFormat Object
----------------------------
The StdDataFormat object enables you to use predefined or custom formats,
intervene in the formatting or unformatting process, and apply these formats to
bound controls. Also, because this is an object, you can reuse it wherever you
need to have this same format.
The StdDataFormat object supports some built-in types and named custom types,
such as Boolean, Currency, and Short Date (in fact, anything that the Format$
function in Visual Basic supports). However, in the example that follows, the
Format and UnFormat events of the StdDataFormat object are used to perform a
custom format conversion rather than a standard conversion.
1. In Microsoft Windows XP, Microsoft Windows 2000, and Microsoft Windows NT:
On the Windows Start menu, point to Programs, point to Administrative Tools,
and then click Data Sources (ODBC).
In Microsoft Windows 98 and Microsoft Windows 95:
On the Windows Start menu, point to Settings and then click Control Panel.
Double-click the "ODBC Data Sources (32-bit)" icon.
The ODBC Data Source Administrator dialog box appears.
2. In the "ODBC Data Source Administrator" dialog box, perform the following
steps:
a. Create a System DSN for a Microsoft Access database.
b. In the Data Source Name box, type "FmtDemo" (without the quotation marks).
c. Click Select to select the Nwind.mdb file.
In the default configuration for Visual Studio, the Nwind.mdb file is
located in the C:\Program Files\Microsoft Visual Studio\VB98 folder. Click
OK.
d. Click OK again.
3. Start Visual Basic 6.0 and create a new Windows application (Standard EXE).
4. On the Project menu, click References.
5. Select "Microsoft ActiveX Data Objects Library 2.1" to enable access to ADO.
If you have a later version of ActiveX Data Objects installed on your
computer, use that version.
6. Select "Microsoft Data Formatting Object Library 6.0" to enable access to the
StdDataFormat object.
If you installed a service pack for Visual Basic, the library name includes a
reference to the service pack. Select this option to enable access to the
StdDataFormat object.
7. Click OK.
8. On the Project menu, click Components. Select "Microsoft Data Grid Control"
and "Microsoft ADO Data Control", and click OK.
9. Add a data grid to the form. Press F4 to view the Properties window. Verify
that the new data grid is called DataGrid1.
10. Add an ADODC control to the form. The control has the default name Adodc1.
11. Select the Adodc1 control in the Properties window. Set the ConnectionString
property to DSN=FmtDemo.
12. Set the RecordSource property for Adodc1 to the following:
Select OrderID, CustomerID, OrderDate FROM Orders
13. In the Properties window, select the DataGrid1 control. In the DataSource
property, type "Adodc1" (without the quotation marks). This binds the grid
to the data control.
14. On the View menu, click Code. Type the following statements above the code:
Option Explicit
Private WithEvents MyFmt As StdDataFormat
This code creates a StdDataFormat variable called MyFmt. This variable has
the WithEvents attribute, to enable event handling for the MyFmt object.
15. Type the following code to handle the Load event on the form:
Private Sub Form_Load()
Set MyFmt = New StdDataFormat
MyFmt.Type = fmtCustom
Set DataGrid1.Columns(1).DataFormat = MyFmt
End Sub
This creates an instance of the StdDataFormat object to store in MyFmt,
defines it to be a custom formatter, and binds it to a specific column in
the data grid (this is the second column because the column array is
zero-based).
16. Type the following code to handle the Format event on the StdDataFormat
object:
Private Sub MyFmt_Format(ByVal DataValue As StdFormat.StdDataValue)
With DataValue
.Value = UCase(Mid(.Value, 1, 1)) & LCase(Mid(.Value, 2))
End With
End Sub
The Format event occurs after the data is retrieved into the record, but
before the bound controls get the data to be displayed. DataValue is the
value that comes into the StdDataFormat object from the ADO recordset. If
you change this value, you change the text that is displayed on screen. In
this example, the data is converted from its incoming format of uppercase to
a mixed-case format in which only the first letter is uppercase.
17. Type the following code to handle the UnFormat event on the StdDataFormat
control.
Private Sub MyFmt_UnFormat(ByVal DataValue As StdFormat.StdDataValue)
With DataValue
.Value = UCase(.Value)
End With
End Sub
This event occurs just before data is sent to the database. The code performs
reverse conversion; it converts all entered text to uppercase.
Verify it Works
---------------
1. Run the application. Data for the CustomerID column is displayed on the
screen in mixed case. You can enter data for this column in either uppercase
or lowercase.
2. On the Add-ins menu, click Visual Data Manager. This runs the VisData
application.
3. On the File menu, point to Open Database, and then click Microsoft Access.
4. Open the Nwind.mdb file.
By default, it is located in the following folder:
C:\Program Files\Microsoft Visual Studio\VB98\NWind.mdb
Click Open.
5. In the Database window, double-click the Orders table. The data that was
edited in the CustomerID column is converted back to uppercase when stored in
the database.
Troubleshooting
---------------
This example does not verify any data. Therefore, if the converted value after
the UnFormat event occurs is not a valid value for the given column, an error
message appears.
REFERENCES
==========
For additional information about how to use a built-in format of the
StdDataFormat object, click the article number below to view the article in the
Microsoft Knowledge Base:
Q191717 HOWTO: Display Boolean Values in Bound DataGrid
Additional query words:
======================================================================
Keywords : kbAudDeveloper kbHOWTOmaster
Technology : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVB600
Version : :6.0
Issue type : kbhowto
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