User Guide

138 Chapter 9 Building Dynamic Forms
Usage notes
• In cftree, the preservedata attribute causes the tree to expand the tree to the
previously selected element. For this to work correctly, you must also set the
completePath attribute to True.
• The
preservedata attribute has no effect on cfgrid. If you populate the control
from a query, you should update the data source with the new data (typically by
using
cfgridupdate) before redisplaying the grid. The grid then displays the
updated database information.
Browser considerations
The applet-based controls for cfform—cfgrid, cfslider, cftextinput, and
cftree—use JavaScript and Java to display their content. To allow them to display
consistently across a variety of browsers, these applets use the Java plug-in, and not
the browser’s native Java runtime. As a result, they are independent of the level of
Java support provided by the browser.
ColdFusion downloads and installs the browser plug-in if necessary. Some browsers
display a single permission dialog box asking you to confirm the plug-in install.
Other browsers, particularly older versions of Netscape, require you to navigate
some simple option screens.
Because the controls use JavaScript to return data to ColdFusion, if you disable
JavaScript in your browser it cannot properly run forms that contain these controls.
In that case, the controls still display, but data return and validation does not work
and you may receive a JavaScript error.
Because Java is handled by the plug-in and not directly by the browser, disabling
Java execution in the browser should not affect the operation of the controls. If for
some other reason, however, the browser is unable to render the controls as
requested, a "notsupported" message displays in place of the control.
You can use the
cfform tag’s notsupported attribute to specify an alternate error
message.