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Richard (Rik) Brooks

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Top Stories by Richard (Rik) Brooks

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 the post open and why was it not just put at the end of the open event? At first I was really confused by the question. It was like he was asking me why do we have arrays? I just couldn't imagine not knowing the answer. Then it occurred to me that I learned the answer to that question from a ... (more)

Appeon Developer Configuration

Have you ever used a datastore that ran without a problem while you were developing your application, but once you've compiled it stopped running? Let me tell you that's a difficult bug to fix. I remember it so well. I kept going back and forth. How in the world could the DataWindow work at design time yet not in the executable? I remember that I checked the return value of the datastore. I finally noticed that the datastore returned a -1. That's such a strange thing. The datastore returns the number of rows that were returned or a -1. The help files used to say that a -1 was in ... (more)

DataWindow Magic: Master_Detail Object

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 exam... (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)

Advanced DataWindow Sorting

This article provides a means of automating the sorting of DataWindows... not just grid DataWindows as discussed in last month's article, but all DataWindows, regardless of display format. Bear in mind that we are writing programmer tools. When writing for programmers we want to give the programmer the maximum number of options while minimizing the programmer effort. In other words, default as much as possible but allow the programmer to move beyond the defaults. We have several action items to implement: Do the housekeeping to get an application going Create a window for sorting.... (more)