Sunday, October 4, 2009

Interacting with HTML Editor Items in Oracle Apex

Oracle Apex ships with a rich text editor to enhance text area items; "HTML Editor Standard" and "HTML Editor Minimal". As you may know, this is actually FCKeditor (renamed CKEditor in the last release). This post is a short description on how to interact with FCKeditor API.

About the FCKeditor API
The API is documented on DKSource Docs. In my case, I only needed to paste something into the editor instance, but there are a number of things you can do. Basicly there are methods you can call to get/set values and properties from the editor instance, and there are events you can listen to, and override default behaviour.

My case
During creation and editing of articles, I wanted to be able to add images into the editor by the simplest means possible. And the images (when the article was displayed) should open in Lightbox2.

So, I had:
  • A table of images (ordimage data type)
  • An application process to serve both thumbnails and whole images
  • A report with thumbnails
  • A page item of type HTML Editor Standard
  • Lightbox2
A couple of notes here. The application process was based on an article by Carsten Czarsky on the German Apex community pages. There are more gems hidden among these community pages, but being written in German they don't show up in my web searches very often. Google Translate to the rescue, my German is not good to say the least... Just remember to keep the original page close by when copying code, as the code examples gets translated too :-)

Integrating Lightbox2 into Apex was described by Denes Kubicek (creator of the mother of all Apex sample apps), I have used a slightly modified version by Sébastien Grosjean (auto resize to browser window), but integrating with Apex is the same as the unmodified version.

Communicating with the FCKeditor
First of all I created a small javascript function in the html header. The function was to accept a string to be pasted into the editor.

function f_pasteEditor(htmlSnippet)
var oEditor = FCKeditorAPI.GetInstance('P12_TEXT');
P12_TEXT being the HTML Editor Standard item.

Next I created a report column, and edited the column link properties:
  • Link Text: Paste text
  • Target: URL
  • URL: javascript:f_pasteEditor('SomeTextToBePasted');
It actually works! No great accomplishment perhaps, but a step in the right direction :-)

Setting up the URL
...or The Great Escape. In my case, the pasted text would have a very specific syntax:
<a href="imgprocess" rel="lightbox"><img src="imgprocess" title="image name"></a>
and imgprocess is a call to an application process which looks like this:
Look at the URL in the link target above, what could possibly go wrong here? (or: what went wrong for me!)
  • If the name of the picture contains a single quote character, it will blow up. Single quotes has a meaning in javascript. Replacing it with unicode escape character "\u0027" will solve the issue.
  • Double quotes has a meaning in HTML, putting double quotes into target URL will have an impact. Replacing it with unicode escape character "\u0022" or (if the output is HTML) "&quot;" will solve the issue.
  • Apex substitution variables gets, er.. substituted! My resulting link in FCKeditor was supposed to contain substitution variables, when they are substituted in the report, that is a bit of a problem.
  • The Apex report would simply blank the column containing the URL (hm... this was probably a fault entirely created by me, but helps to understand my solution ;-))
I solved this the quick and dirty way, by extending the javascript function, and hardcoding the link there:

function f_pasteImg(p_item_name, p_image_id, p_alt)
var htmlSnippet = '<a href=\"f?p=&A'+'PP_ID.:&AP'+'P_PAGE_ID.:&S'+'ESSION.:APPLICATION_PROCESS=getImage:::P_IMAGE_ID,P_THUMBNAIL:'+p_image_id+',N\" rel=\"lightbox[myPicts]\"><img align="left" alt=\"'+ p_alt +'\" src=\"f?p=&AP'+'P_ID.:&A'+'PP_PAGE_ID.:&S'+'ESSION.:APPLICATION_PROCESS=getImage:::P_IMAGE_ID,P_THUMBNAIL:'+p_image_id+',Y\"></a>';
var oEditor = FCKeditorAPI.GetInstance(p_item_name);

Note how the Apex substitution variables are divided with "'+'" so the Apex engine won't replace it, and how the double quote are escaped by "\". Quotes in the alt-text are replaced with it's HTML/unicode counterparts in the SQL-query. I also cheat a bit by aligning the picture to the left, but this can easily be changed with FCKeditor later.The images will not show up in the preview window, because of the unsubstituted substitution variables (phew!).

As long as the images are served through an application process (to apply security) and not through a public procedure, this will be the result. But when the article is displayed, and session variables properly substituted, the thumbnails are properly displayed

So now my articles shows clickable thumbnails which displays the full picture in Lighbox2 :-)

The result?
Despite my shaky implementation, the users are left with a simple way to include pictures into their articles. That was pretty much the point. The users doesn't need to know it's held together with chewing gum and a piece of string.

As for me, I start to realize that javascript can do pretty much everything, and that sometimes it is a pain to get it to do anything...

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