Enhancing Web.PB with the Starfire Class Library

by Don Draper

Page 1

For those of you who have taken the plunge into Web.PB, you know how nice it is to have the  power of PowerBuilder and datastores for creating dynamic web content. All web applications use some language to create the content and provide the logic. By coding your logic in Powerscript, you gain all the power you are accustomed to in regular PowerBuilder applications, including datastores for database access. Add to that the Web.PB class library that assists in creating HTML content and session management and you really a have powerful arsenal.

However, there is currently no easy way to get data from a datastore translated into an HTML form or from a form back into a datastore. An HTML form becomes our editing interface just as datawindows are in PowerBuilder. Much coding is required to create HTML forms if we create each field of the form dynamically as needed. This is true despite the fact that the Web.PB class library provides a wealth of functions to produce almost any type of web page object.

PB 6.0’s GenerateHTMLForm( )

Powersoft attempted to alleviate some of the problem by providing a new function named GenerateHTMLForm() in PowerBuilder 6.0. Unfortunately, this new feature comes up short on functionality limiting its usefulness to simple forms.  

The most serious issue is that a while drop-down datawindows get translated into dropdown list boxes in HTML, the list only contains the single item present in your main record. Gee, what was the point? Only list box edit controls with code tables get translated with list data intact.

Other flaws include the fact that the HTML edit controls include MAXLENGTH but not SIZE attributes. Also, some datawindow attributes don’t get translated as you might expect.

Even if the GenerateHTMLForm() function worked as you would expect, the form creation and display of the data is only half the battle. You still must create a method that can process the form’s data once it gets submitted. You might think someone could really fill this gap.

Starfire to the Rescue

Just when you thought all hope was lost, STEP Consulting comes to the rescue. Rob Stark and Greg Swanson set out to extend the Web.PB class library to handle these issues. And handle they did. 

They created the Starfire library. Starfire started out as a small library to help one of their clients do web development with PowerBuilder. Since then, it has taken on a life of its own. If you give it try, you’ll quickly see why!

The library dynamically creates HTML forms from datawindows that are fully editable back to the database, all with very little coding. You can have a master list that provides hyperlinks that return the detail record in a form ready for editing. Dropdown datawindows get converted to dropdown list boxes complete with data. Check boxes and radio buttons are translated appropriately and even computed columns are handled with ease. Wow! Imagine leveraging your datawindows right into your Web applications.

Rob and Greg did not stop there. The library also translates edit masks and required attributes into some very clever logic in Javascript. This javascript is generated right along with your HTML form. Javascript is often used to provide client-side validation and informs the user of validation errors before the data gets submitted to your server application.

The javascript created by Starfire is tailor made to your datawindow. It checks for required fields and edits date fields for valid dates and proper date formatting. In addition, it provides logic to encode the form’s data into a single string to be cleverly passed to a generic function. This generic function is how Starfire is able to automatically handle updates to the database from any datawindow form. Without Starfire, you must manually create a function with arguments that accept each item from your form, get the data back into the datawindow and manage the update.

 Listing 1 shows how few lines it takes to set up relationship between a list (master and form detail) relationship. Many options are set with simple function calls. It could not be much easier to learn or use.