Friday, December 08, 2017

How do I create a responsive Rich Text Editor in Oracle APEX?

I was in a video call this morning with a great customer from England (and by the way, this customer is in the process of transforming the healthcare industry across the UK).  They asked me a very simple question:

How do I create a responsive Rich Text Editor item on a page?

Simple question and answer, right?  Well, you'd be wrong.  While we pride ourselves on the responsive user interfaces that you can easily create with Oracle Application Express (APEX), unfortunately, the item type of Rich Text Editor is not responsive, out of the box.

So - I did what all smart people do, and I reached out to the Oracle APEX Development team, in this case, the ever-intelligent Carsten Czarski.  And in a few minutes, he showed me exactly what I needed to do.

  1. Open up Application Builder, and in Page Designer, edit the page with the Rich Text Editor item.  In my example, my Rich Text Editor page item name is P3_RESUME.
  2. Navigate to the attributes of the Rich Text Editor item, and in the Advanced section, enter the following code in the "JavaScript Initialization Code" attribute:
    function (o) {
        o.width = $("#P3_RESUME").closest(".t-Form-inputContainer").width() - 5;
        o.height = 300;  // Specify your desired item height, in pixels
        return o;
    This code determines the width of the region container of the item, subtracts 5, and returns the object initialized to this size.  This will take care of the Rich Text Editor when the page is initially displayed. But it won't handle the case when the browser is resized. To handle that case, we'll need to add a dynamic action.
  3. Click the Dynamic Actions sub-tab in Page designer (the lightning bolt)
  4. Select Events in the upper-left, right-click your mouse and choose "Create Dynamic Action".
  5. In the attributes, enter "Resize" for Name, and select "Resize" for the Event.
  6. Select the True action of the dynamic action (it should be "Show").  Change the Action to "Execute JavaScript Code".
  7. In the Code attribute, enter the code:
    CKEDITOR.instances.P3_RESUME.resize( $("#P3_RESUME").closest(".t-Form-inputContainer").width() - 5, 300);
    This is an absolute reference to the Rich Text Editor item on the page, named P3_RESUME. And like the code before, this will determine what the width is of the container of the item, subtract 5 from it, and invoke the resize() method of the Rich Text Editor (CK Editor) element.
That's all there is to it!

Obviously, this item type (like all others) should be responsive, out of the box.  And Carsten is looking at this for the next version of APEX.  In the meantime, if you're using Universal Theme with Oracle APEX 5.1, all it takes is a tiny amount of JavaScript to get a responsive Rich Text Editor.

Thursday, December 07, 2017

Errors when downloading a file on page submit in Oracle Application Express 5.1 or later...

Recently, Sharon Kennedy from our team approached me for some help with file download in Oracle Application Express (APEX).  Sharon is the primary developer of Oracle Live SQL (among many of her other responsibilities), and she wanted to initiate a file download in a page process, after page submission.  Since I've done this 100 times in APEX applications, should be easy, right?

Back in 2014, I wrote a short blog post showing how to generate a link to download a file from a BLOB stored in a table.  But this problem was slightly different.  The application flow was:

  1. In Oracle Live SQL Administration, an administrator would click the button "Download Oracle Content"
  2. The page would then be submitted, and a PL/SQL page process would fire, which would query all of the static scripts and tutorials from Live SQL, zip them up using APEX_ZIP, and initiate a file download.

However, when the button was clicked, the page would be submitted, no file download would be initiated, and the following error was displayed on the page:

Error: SyntaxError: Unexpected token r in JSON at position 0

After spending more than an hour debugging the Live SQL application, I resorted to a simpler test case.  I created a trivial application with a button on the first page, which would submit and invoke the PL/SQL page process:

    l_file_blob blob;  
    l_file_name apex_application_files.filename%type;  
    l_file_mimetype apex_application_files.mime_type%type;  
    select blob_content, mime_type, filename into l_file_blob , l_file_mimetype , l_file_name from apex_application_files where id = 2928972027711464812;     
    sys.owa_util.mime_header( l_file_mimetype , false );  
    sys.htp.p('Content-Disposition: attachment; filename="' || l_file_name ||'"');  
    sys.htp.p('Content-length: ' || sys.dbms_lob.getlength( l_file_blob ));  
    sys.wpg_docload.download_file( l_file_blob );  
    -- Stop page processing  
    apex_application.stop_apex_engine ;  

With my test case, it was exactly the same error encountered, the meaningless error message of "Error: SyntaxError: Unexpected token r in JSON at position 0".

I finally gave up and contacted Patrick Wolf on the APEX product development team, who helped me solve this problem in one minute.  Granted...Patrick was both the creator of the problem and the creator of the solution!

To resolve this problem:

  1. Open the page in Page Designer in Application Builder
  2. Edit the page attributes
  3. In the Advanced section of the page properties on the right hand side of Page Designer, change "Reload on Submit" to "Always" (changing it from "Only for Success" to "Always")
That's it!

Setting "Reload on Submit" to "Always" will POST the page and render the result using the behavior as it was in APEX 5.0 and earlier.  In APEX 5.1, if Reload on Submit is set "Only for Success" (the default), it will use the new optimized page submission process, and expect a specifically formatted JSON result returned from the APEX engine.  Obviously, when I employ a page process which overrides the HTP buffer and emit binary content (instead of a well-formed JSON result), the libraries on the page don't know how to deal with that, and thus, results in this obtuse "Unexpected token r..." message.