Richard (Rik) Brooks

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Top Stories by Richard (Rik) Brooks

One of the most useful custom objects that I've ever written is my master_detail object. It holds a prominent place in my toolkit. This article will take you through the steps of how to write one and in the process de-mystify the object. First we want something that looks like Figure 1. Selecting a row in the top DataWindow will display the details in the bottom. I'm sure that you've seen this kind of DataWindow and you've probably written many of them. The key here is not to tell you how to write this but how to simplify every one that you will write in the future. For our example I will again use the example database that came with PowerBuilder. To build the control I first need to create a new custom object. I click on File-New in the menu or just hit Ctrl-N and I get the dialog in Figure 1. I've circled what you need to click on to make it easy for you. Once y... (more)

Extending SQLCA

We are going to create a bare-bones email object. Of course you can expand that in the future if you like, but for now, let's just create the functionality that we need. I start by creating a custom class. In case you aren't familiar with the process look at Figure 1. Let's start with an instance variable. N_cst_mailer Instance Variables private mailMessage io_mail_message // The message to send I made the instance variables private so let's write a couple of functions to populate our mail Message. We'll start with the TO. Note that the io_mail_message contains an array of objec... (more)

DataWindow Sorting with Column Headers

This article describes how to create a grid presentation window that allows sorting by clicking on the column header. To begin we need to create a grid DataWindow. I'm selecting just a few columns from the employee table. Here is my sql for the DataWindow in Figure 1. Once we have created it I get the DataWindow painter shown in Figure 2. There are several changes that we need to make. Let's change the status column so it's no longer a set of radio buttons. This is a read-only screen so let's remove the status and add a computed field. To do this let's remove the Status column ... (more)

Automating Your DataWindow

Every programmer knows about the IF command. It's pretty much a fundamental part of the syntax of every computer language that has ever existed. I don't need to explain how it works. The DataWindow can't use the IF command though. It does, however, support an IF function. IF(expression, TRUE, FALSE) In its simplest form this means that if the expression evaluates to TRUE, then whatever statement you supply for the TRUE part is executed. If not then the FALSE part is. Let's begin with a simple example. Let's create a DataWindow that will show employee information. Here is the SQ... (more)

The PostOpen Event – Why It Is So Important

Normally I try to write applications on the DataWindow or Appeon but every now and then I get a question that makes me sit back and say, "Huh?" In this case the question concerns the PostOpen event. I've seen that event named different things: ue_post_open, postOpen, post_open, ue_postOpen, etc. It has, as far as I can see, always had post and open in the name of the event. Further, just about every framework that I've ever seen has had that event in the base window. The question that I was asked was, "Why is that event there?" The programmer wanted to know why there was code in t... (more)