Saturday, 1 August 2020

New Plug-in: Reacting on changed content of APEX Autocomplete Item

Why use Text Field with autocomplete

Right now I am developing a series of mobile applications for personal use. And of course I learn a lot about developing with Oracle APEX for mobile.
I like to use auto complete items in mobile apps because to my opinion select lists are less suited for mobile use most of the time. One of the reasons is that in long lists, in contrast to in desktop applications, you cannot filter on the first character. Because you do not have a keyboard! So you have to scroll a lot. On iPhone this takes place on the bottom of the screen where you see only about three items at a time. I once checked in for a flight using the mobile app from the airline. I had to select my country (The Netherlands) from a select list of some 200 countries four times. And each time it took me about 30 secs to scroll through the 170 countries until I reached The Netherlands.
With an autocomplete item it would take 2 secs to type in a discriminating 3 or 4 characters to get to the result.
So that is why I prefer to use Autocomplete items. But I found out there is a problem with reacting on when the content of such an item changes. A Dynamic Action of type Change does not fire when the value of an Autocomplete item is selected.

Reacting on change of Text Field with autocomplete

A quest for an answer on the internet revealed, that a special event type should be used. Under the heading Component Events we can find: Update [Text Field with autocomplete].

When using this event to define a Dynamic Action, the DA fires the moment a value from the suggestion list of the autocomplete item is chosen. So contrary to the Change event the focus is still on the Autocomplete item. Furthermore there is no reaction on values entered that are not in the suggestion list.

So I started off to find a way to detect changes in the Text Field with autocomplete.
I defined a On Focus DA in which the current value is stored into an attribute old-value of the input item. In a Lose Focus DA this value is retrieved and compared to the current value of the item. If there is a difference, action can be taken. Then I selected a value form the auto complete suggestion list. This took the focus away from the Autocomplete item, and the change event was triggered.
So the Lose Focus DA does not work.
With some googling I found out that only input, select, textarea, anchor and button elements can receive focus. So I could try to implement the code in Lose Focus in the Get focus actions for the other elements. And this works!

But it is quite cumbersome to define these actions for each Autocomplete item and all the other elements we want to monitor. Besides the task would be difficult for developers who are not so familiar with JavaScript. So I decided to create a plug-in for it.

Autocomplete change detection DA Plug-in

So I have developed a plug-in for watching changes in Autocomplete items and triggering an event when a change is detected.
You can find the plug-in on
You can apply this plug-in on Page Load. The plug-in automatically watches all Text Fields with autocomplete on the page.

When the value of an Autocomplete item is changed, an event is fired from that autocomplete item. You can find the event in the event in the Component Event chapter of the Event list, as you can see in the DA definition below:

Happy APEXing.

APEX 20.1 nugget: Mega menu's

A few days ago I downloaded and installed APEX 20.1. I was inspired by the presentations of Shakeeb Rahman and Patrick Wolf on ODTUG Learn from home. They talked about mega menu and user friendly URL's. And I thought, I want to have this too!

So I downloaded the installation package, studied the installation/upgrade manual carefully, and followed the instructions as well as possible. In the past I have had troubles with ords and static files support after upgrading, costing me hours to fix. This time everything went smoothly and after performing all the indicated steps I fired up my new APEX 20.1, and it worked :-).
I suppose it pays to RTFM.

Mega menu's

Mega menu's provide a large menu, where you have all the menu options available at once. 
In my APEX demo application the menu's have been a constant struggle for me. I wanted all the pages to be reachable from the menu directly, but this way the menu grew too long and the options disappeared below the bottom of the screen (even on my 27" iMac!). 
So mega menu's were very promising. And indeed they did fulfill my expectations.:

The nice thing is that Mega menu's work on the same data as the original APEX side menu. So initially you do not have to change anything to start using them. Just change some setting in the User Interface and you have your own Mega Menu:

You can visit my APEX demo application to see the Mega Menu in action. It took me about half an hour to reconstruct the menu. Btw, do you notice the user friendly URL? 

Of course once you have got your menu, you can tweak the content to your liking. Watch this video by Shakeeb Rahman on Mega Menu's. Unfortunately I was not able to find a recording of the webinar from ODTUG Learn from Home Series in which Shakeeb demonstrates what you can do with Mega Menu's in great detail. 

Happy APEXing

Wednesday, 12 February 2020

Oracle APEX Geolocation 1: How to get your location

Some decades ago people used to work in an office. And occasionally they went on business trips. Nowadays users are much more mobile. They can work from home, form the office or from a field location. So their location varies and it can be useful information for the applications they use.The location might be tied to a customer or a fact that should be reported. This series of blogposts will deal with determining the location in Oracle APEX, and how to use and display it:

Part 2: Using Oracle Spatial
Part 3: Display location(s) on map
Part 4: Correct locations on map
Part 5: Getting location data from photos

The parts without link are not yet available.

There is an example application available at :

Getting your location in the browser

In order to retrieve your GPS location in the browser some JavaScript needs to be applied:

function getLocation() {
  if (navigator.geolocation) {
    navigator.geolocation.getCurrentPosition(function(position) {
        alert(`Latitude: ${position.coords.latitude} \n` +
              `Longitude: ${position.coords.longitude}`);
  } else {
    alert("Geolocation is not supported by this browser.");

The most important line is the call to navigator.geolocation.getCurrentPosition.
 This is the function to retrieve the GPS location. As this may take several seconds the function is asynchronous.  The function to be performed after retrieval of the location is the argument for the function. There also is a check when the function is not available.
After the call JavaScript will immediately continue with others tasks. Otherwise the page would hang until the function returns.

NB The function can only be called from a https web site.


In ideal situations the accuracy of the location is within a few meters. In less favorable situations this might expand to tens of even hundred of meters. Especially in an urban environment with many high buildings the visiblity of the GPS sattelites is less good and the accuracy is less accordingly.
More information on GPS accuracy can be found  here


Privacy can be an issue when you retrieve and store the location of employees, customers etc. The privacy legislation differs per country.
As of May 2018 the General Data Protection Regulation is issued by the EU. This law contains high penalties for offenders. It is wise to take notice of the privacy regulations in the countries where the application will be used.

Getting location using a APEX plug-in

For APEX developers it is not necessary to write JavaScript to retrieve the GPS location. You can use the Store location plug-in that can be found on

After importing the plug-in in your application, you can reference it in a dynamic action. All you need to fill in are the APEX items to store the latitude and longitude once the location is retrieved.

To define follow-up actions a custom DA can be defined acting on the event location-retreived.

Happy apexing ;-)