Roels Blog

Most applications need some sort of "configuration" table. A simple key-value store where you can put values that might change on a different environment, like URLs, minimal password length, API keys, etc. And very conveniently APEX has this implemented as " Application Settings ": A simple table containing a key and a value - and a few other properties like "valid values". In your code you can reference these values using either the apex_application_settings view - that contains all Application Settings in your Workspace - or the apex_app_setting API - that you can use to get or set a value based on the Application Settings Name. That's all great. Until I ran into this situation: Our "application" consists of 2 APEX applications, one Internal (INT), backoffice kind of application and one external (EXT) facing one. And now I needed to set the Application Setting of the EXT application from the INT application. While I can see the current va...

 If you run your APEX application - like a Form based on the EMP table - and test if you can change the value of Department to something else then the standard values of 10, 20, 30 or 40, you'll get a nice error message like this: But it isn't really nice, is it? So what do a lot of developers do? They create a validation (just) in order to show a nicer, better worded, error message like "This is not a valid department".  And what you then just did is writing code twice : Once in the database as a (foreign key) check constraint and once as a sql statement in your validation. And we all know : writing code twice is usually not a good idea - and executing the same query twice is not enhancing your performance! So how can we transform that ugly error message into something nice? By combining two APEX features: the Error Handling Function and the Text Messages! Start with copying the example of an Error Handling Function from the APEX documentation. Create this function ...

Almost every APEX Developer knows that JavaScript and CSS belongs in separate files and (in 99% of the use cases) not somewhere in your Page properties. If you have this code in separate files it is easier to use them in a Version Control System (SVN or Git) - if the files are outside of APEX. And the code you store in these files can be reused, in contrast to the stuff you store on Page level. In a lot of environments it is harder to use external files, because deployment of these files to the appropriate location on a webserver requires special privileges that not everybody has. In those cases storing these files as Static Application Files or Static Workspace Files might be a better solution. It makes deployment easier, because these files will be exported and imported as part of the application. You can't accidentally forget about them. But working with these files is quite a pain. When you need to edit something you have to download that file, make the changes, upload it again...

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...

The APEX Interactive Grid uses the Toolbar widget to create the default Toolbar showing the Search box, Actions menu, Save button etc. And since quite a while there is a nice Plugin " Extend IG Toolbar " by Marko Goricki that makes it very easy to add additional buttons to the Toolbar. But what if you need more than a button?  Inspecting the contents of widget.toolbar.js, you can easily spot there can be added more to the Toolbar than just a button: The type of control, available values: "STATIC", "TEXT", "SELECT", "BUTTON", "MENU", "RADIO_GROUP", "TOGGLE". The first example will show a way to easily switch from one filter to another. Of course we could use the standard functionality and create two different Report views, but using a Radio Group on the Toolbar gives a more "Tab" like user experience. So how can we create a Radio Group that looks like a switch in the Toolbar? In...

If you are using multiple containers to set up your Oracle Development (or Test or Production) environment - as I described here - you probably ran into the issue that your ORDS container was started before the Database was started up. This results in an ORDS container that is not working - at least not as you need to. Using Docker Compose you can specify a depends_on option, for instance in the ORDS container configuration you specify (where "oracle" refers to the container that holds the Oracle database) : depends_on : - oracle but this only means the ORDS container will start after the "oracle" container has been started. That does not mean the Oracle database inside the container is started and available! So how do we tell the ORDS to configure itself in one container to wait for the database in another container is ready to use? Step 1: Start the Oracle database (container), connect to it and enable a port - in this example 8080 - in the...

Imagine you have a nice APEX application, but on a certain day your client asks you to remove a column from the application. So after a thorough dependency analysis it appears that that column is only used in two pages : One Interactive Report and one Form.  So you go ahead and start with the hard work and delete the column from the table. Now you only have to fix the application, right? So - just in case of "you never know whether the client will change his mind again" - you decide to set the "Server Side Condition" of the column in both the Report and the Form to "Never". That should do the trick! Of course you do test, and fire up the report. Works as expected, the column is not shown on the report anymore. Then you click the little pencil link to open the Form.  And an error pops up: WTF? I was pretty sure I set the Condition to Never! So why is it still trying to fetch that column? Luckily there are more ways to not show an Ite...

After a few nights of good sleep (that means more than the average 4 to 5 hours at Kscope), it is time to sit back and evaluate what happened last week. I arrived on Thursday night before the event, just in time to catch Danny Bryant at the bar for "just one last beer" (I don't know how often I heard, and used, that phrase last week). The whole Friday was filled with an all day Board Meeting, mainly discussing the future of ODTUG, a reception and a fine dinner. Since a couple of years, Saturday is the Community Service Day. This year, an impressive number of people showed up and were transferred to "Up Orlando", to make its easier for them to help the people that really need some help. All kinds of different activities were done, like cleaning, filling shelves, painting chairs etc.  After that there is another tradition: bag stuffing. All those (about 1500) bags didn't get delivered with all those goodies in there! A number of volunteers created the most ...

If you created your own "updatable reports" or your custom version of tabular forms in Oracle Application Express, you'll end up with a query that looks similar to this one: then you disable the " Escape special characters " property and the result is an updatable multirecord form. That was easy, right? But now we need to process the changes in the Ename column when the form is submitted, but only if the checkbox is checked. All the columns are submitted as separated arrays, named apex_application.g_f0x - where the "x" is the value of the "p_idx" parameter you specified in the apex_item calls. So we have apex_application.g_f01, g_f02 and g_f03. But then you discover APEX has the oddity that the "checkbox" array only contains values for the checked rows. Thus if you just check "Jones", the length of g_f02 is 1 and it contains only the empno of Jones - while the other two arrays will contain all (14) rows. So for ...

Recently someone asked me how he could implement multiple authentication schemes for his APEX application. He would like to use (some kind of) Single Sign-on authentication and - as an alternative - an Application Express Authentication. The problem is ... you can only define one Authentication Scheme being "Current" for an application! So how can we solve this issue? First, we need te be aware that multiple applications can share their authentication by using the same cookie. Thus if you specify "MYCOOKIE" as the Cookie Name in Application A as well as in Application B, you can switch from A to B and back without the need of logging in again. It doesn't matter what Authentication Scheme Type you are using! Knowing this, we are halfway our solution. We need two Applications. One - the "real" application - using the Application Express Authentication, let's name this one "LAUNCHPAD". And another one using the Single Sign-on Authenticat...

Nowadays Docker is everywhere. It is one of the main components of Continuous Integration / Continuous Development environments. That alone indicates Docker has to be seen more as a Software Delivery Platform than as a replacement of a virtual machine. However ... If you are running an Oracle database using Docker on your local machine to develop some APEX application, you will probably not move that container is a whole to test and production environments. Because in that case you would not only deliver a new APEX application to the production environment - which is a good thing - but also overwrite the data in production with the data from your development environment. And that won't make your users very excited. So in this set up you will be using Docker as a replacement of a Virtual Machine and not as a Delivery Platform. And that's exactly the way Martin is using it as he described in this recent blog post . It is an ideal way to get up and running with an Oracle d...

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...