Form Management

Last Updated: 5/6/2009

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Topics in this section:
Form Management
User Controls
IntraWeb Frame
Managing Forms
Form List
Showing Forms
Hiding Forms
Destroying Forms
Passing Data

All forms used by an IntraWeb application must be an IntraWeb-specific form. Working with IntraWeb forms differs a little bit from working with standard Delphi forms. For instance, any form that is displayed must be done using the Show method of the form. In other words modal show is not permitted or supported.

IntraWeb for Delphi

The repository contains another icon, which is the IntraWeb Form. All new IntraWeb forms should be created using File | New and choosing the IntraWeb Form. Standard Delphi forms are not compatible with IntraWeb. A new unit and form will be created and displayed on the screen.

Update Modes

Note: Partial Updates are scheduled to be deprecated in a future version of IntraWeb as they have been superceded in functionality with the addition of AJAX. umPartial has some features not available in AJAX, but the use of AJAX allows IntraWeb to reuse more common libraries.

Application forms have a property, called UpdateMode. Its default setting is umAll, which provides the traditional way of completely updating a page when it gets sent back to the users Web browser.

Setting UpdateMode to umPartial will cause the form to refresh ony the controls that need refreshing, this improving significantly the speed of your application, especially over slower connections. Using Partial Updates just a delta package, which reflects the changes of the current page, will be sent over the wire. Depending on the total number of controls on your page, this will majorly reduce the used bandwidth, you won't also notice any flickering during the refresh. Even better, scrollbars will keep its position.

Partial Update is the most innovative technology in web development. However, due to the heavy use of DHTML, this update mode is available only on latest browsers supporting JavaScript and CSS with HTML 4.0.

Limitations of partial updates

The trade off are some features which won't work correctly with umPartial. Some of these limitations will be addressed in future versions of IntraWeb. All limitations listed below are for the latest IntraWeb version. Earlier versions of IW may have had more limitations.

TerminateAndRedirect(AURL, AMsg) won't show the termination message (AMsg)
Creating controls on the fly after the form has been rendered the first time is not supported. Creating controls in the Form's OnCreate event handler, or from any other event which gets called before the form is sent to the browser the very first time, will work though.
The Treeview control does not work in umPartial
File uploading (TIWFile) does not work in umPartial
Runtime assignment of event handlers does not work in umPartial

If your form uses any of the above techniques, then either try to avoid using them or switch this specific form to umAll. Please note that you can have some forms with umAll and others with umPartial being set in the same application.