Roels Blog

Remember Oracle Forms? One of the nice features of Forms was the use of GLOBAL items. More or less comparable to Application Items in APEX. These GLOBALS where often used to pre-query data. For example you queried Employee 200 in Form A, then opened Form B and on opening that Form the Employee field is filled with that (GLOBAL) value of 200 and the query was executed. So without additional keys strokes or entering data, when switching to another Form a user would immediately see the data in the same context. And they loved that. In APEX you can create a similar experience using Application Items (or an Item on the Global Page) for Classic Reports (by setting a Default Value to a Search Item) and Interactive Reports (using the  APEX_IR.ADD_FILTER  procedure). But what about the Interactive Grid? There is no APEX_IG package ... so the first thing we have to figure out is how can we set a filter programmatically? Start with creating an Interactive Grid based upon the good o...

There are some, maybe rare, use case when you want to set the " Suppress Change Event " switch of a Dynamic Action to " Yes ". Usually that's only necessary when the Dynamic Action is fired On Change  and executes a Set Value  with the same field as a target. There might be a chain of events leading to this or just one. If you forget to set it you'll end up in an endless loop and your browser will choke. That works all fine and as expected with regular Page Items. However ... when you apply this to a column in an Interactive Grid something unexpected happens. When you set the Suppress Change Event of a Dynamic Action that fires on change of a column to Yes , the value of that item seems empty when you leave that field (column)! If you navigate back into that field, the (new) value does show up... You can call it a feature, you can call it a bug, but bottom line it is unexpected and undesired behaviour. The solution is to call the Grid method SetActiv...

In my previous post I blogged about pushing changed rows from the dabatase into an Interactive Grid . The use case I'll cover right here is probably more common - and therefore more useful! Until we had the IG, we showed the data in a report (Interactive or Classic). Changes to the data where made by popping up a form page, making changes, saving and refreshing the report upon closing the dialog. Or by clicking an icon / button / link in your report that makes some changes to the data (like changing a status) and ... refresh the report.  That all works fine, but the downsides are: The whole dataset is returned from the server to the client - again and again. And if your pagination size is large, that does lead to more and more network traffic, more interpretation by the browser and more waiting time for the end user. The "current record" might be out of focus after the refresh, especially by larger pagination sizes, as the first rows will be shown. Or (even wors...

For pushing changes from the database to the end user, the regular solution is using websockets. A change in a record is detected - using a trigger or using the CQN (Change Query Notification) feature - and a notification is send to a websocket server. That websocket server broadcasts the notification over a channel to all browsers that are tuned in to that websocket channel. Then the browser reacts to that notification, usually showing an alert or refreshing a report. This trick is described on multiple sites, just Google for " oracle apex websockets " or similar. So back in the old days, we used that notification in the browser to refresh the (interactive) report. But along comes the Interactive Grid (IG) . While he full-refresh mechanism still works for IG, an IG has also the option to refresh just one row.  So wouldn't it be awesome that just the changed row(s) get refreshed upon a change in the database, instead of the whole report? Can we do it ... yes we ca...