About displaying and validating data
When PowerBuilder generates a basic DataWindow object, it uses the extended
attributes defined for the data and stored in the extended attribute
system tables.
For more information about the extended attribute
system tables, see Appendix A, “The Extended
Attribute System Tables”
In the Database painter, you can create the extended attribute definitions that
specify a column’s display format, edit style, and validation
rules.
In the DataWindow painter, you can override these extended attribute definitions
for a column in a DataWindow object. These overrides do not change the
information stored with the column definition in the extended attribute
system tables.
Presenting the data
When you generate a new DataWindow object, PowerBuilder presents the
data according to the properties already defined for a column, such
as a column’s display format and edit style.
Display formats
Display formats embellish data values while still displaying
them as letters, numbers, and special characters. Using display
formats, for example, you can:
- Change
the color of numbers to display a negative value - Add parentheses and dashes to format a telephone
number - Add a dollar sign and period to indicate a currency
format
For information, see “About display formats “.
Edit styles
Edit styles usually take precedence over display formats and
specify how column data is presented. For example, using edit styles,
you can:
- Display valid values
in a drop-down list - Indicate that a single value is selected by a check
box - Indicate which of a group of values is selected
with radio buttons
Edit styles affect not only the way data displays, they also
affect how the user interacts with the data at runtime.
For more information, see “About edit styles “.
About display format masks
and EditMask masks
The differences between display format masks and EditMask
masks can be confusing. A display format mask determines the appearance
of the column when the focus is off the column,
or when the DataWindow object is in print preview mode. When you apply
an EditMask edit style, the mask you use determines the appearance
of the column when focus is on the column.
If you want data to display differently depending on whether
the focus is on or off the column, specify an edit mask (on the
Edit property page for the column) as well as a display format (on
the Format property page for the column), then check the Use Format
check box on the Format property page. The Use Format check box
displays only when an edit mask has been specified.
If you want the data to display in the same way whether focus
is on or off the column and you have defined an edit mask, you do
not need to define a display format. The edit mask is used for display
if the Use Format box is not checked (the default).
Validating data
When data is entered in the Database painter or in a DataWindow object, PowerBuilder evaluates
the data against validation rules defined for that column. If the
data is valid, PowerBuilder accepts the entry; otherwise, PowerBuilder displays
an error message and does not accept the entry.
For more information, see “About validation rules “.