In Application Express(APEX) it is possible to communicate with the database without submitting the entire page. This is extremely useful when your APEX application is being run on a very slow network. This on demand communication is possible in APEX using Asynchronous JavaScript and XML(Ajax). Using this method sends only the minimum information required to retrieve a value from the database. I will explain using a simple example involving the famous emp table.

lets say I have a page that has three items on it

• P1_EMPID. this will be a textfield used to enter the emp_id
• P1_ENAME. this will be used to display the ename
• SUBMIT. this will be a button that will submit the page. this page submission will fire off a process that will populate P1_DISPLAY with the relevant ename for the given emp_id

The issue with the above example is that the entire page has to be reloaded when in fact only one small section will be updated, namely P1_DISPLAY. the following example will demonstrate how to retrieve the name from the database without refreshing the page.


1. Move the database code from the page process and place it in an application process. Name the process "GET_ENAME" and give it a type of "On Demand". example code is below

2. Create the following javascript function.

3. Finally alter the SUBMIT button so that it uses a URL redirect and in the URL field enter

javascript:get_ename();return false;


and thats it, when you press the submit button it will now send the emp_id to the database and populate P1_ENAME with the relevant name. and all without refreshing the page.

obviously this is a trivial example but it gives an idea of the possibilities of Ajax.

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Comments (4)

• |57.82.13.xxx |2010-02-18 13:16:00 J Du Toit  - Complements
  Thank you for this tutorial. Now I understand why ApEx (Oracle) is going to take over the World!

• |94.246.126.xxx |2010-02-19 23:02:26 Anonymous
  only somebody who didn't see anything else can say something like this

• |194.71.67.xxx |2010-02-23 10:04:40 PowPow  - pFlowId
  This doesn't work for me:
  
  var get = new htmldb_Get(null,html_GetElement('pFlowId').value, 'APPLICATION_PROCESS=GET_ENAME’,0);
  
  But this do:
  var get = new htmldb_Get(null,$v('pFlowId'),'APPLICATION_PROCESS=GET_ENAME',$v('pFlo wStepId'));

• |81.246.102.xxx |2010-03-01 16:04:27 Matthias Hoys  - Some remarks...
  Hey,
  
  Nice example, but I have some remarks :-)
  
  The comment from user "PowPow" is correct - for me also it doesn't work with your code - I'm using APEX 3.2.1.
  
  You're talking about P1_ENAME and P1_DISPLAY, isn't that the same page item?? Also, you don't mention the item type of P1_ENAME, should that be a text field?
  
  Next, for beginning users, it might be useful to mention the fact that you need to put Javascript functions between tags before adding them to the HTML header of a page; otherwise the code won't be recognized by the web browser.
  
  I hope these tips help to improve your tutorial ;-)
  
  Regards,
  Matthias

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