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Creating an APEX plugin for an Oracle JET component - Part 2

In my previous blogpost I showed how you can embed an Oracle JET component in your APEX application. Now it is time to make a plugin out of the wisdom we gained doing so.
First of all a disclaimer. My intention is to make this plugin and the inner workings as simple as possible. So you can add a lot more functionality, checks etc and therefore add complexity. But this is intended to be as simple as possible.

The plugin consists of three parts: a PL/SQL render function, a snippet of JavaScript and a PL/SQL ajax function.

The render function is defined as :

function render 
( p_region                in  apex_plugin.t_region
, p_plugin                in  apex_plugin.t_plugin
, p_is_printer_friendly   in  boolean 
) return apex_plugin.t_region_render_result 
is

  c_region_static_id      constant varchar2(255)  := apex_escape.html_attribute( p_region.static_id );

begin
  -- Add placeholder div
  sys.htp.p (
     '<div class="a-JET-PictoChart" id="' || c_region_static_id || '_region">' ||
       '<div class="a-JET-PictoChart-container" id="' || c_region_static_id || '_chart"></div>' ||
     '</div>' );
     
  -- Load the JavaScript library   
  apex_javascript.add_library 
  ( p_name      => 'pictoChart'
  , p_directory => p_plugin.file_prefix
  );
  
  -- Initialize the chart
  apex_javascript.add_onload_code
  ( p_code => 'jet.picto.init('||
                  '"#'||c_region_static_id||'_chart", '          || -- pRegionId
                  '"' || apex_plugin.get_ajax_identifier ||'"'   || -- pApexAjaxIdentifier
                 ')'
  );
  
  return null;
end render;

So what it does in these three steps is :
1. Generate a DIV placeholder, just as we saw in that previous post
2. Load the JavaScript file "pictoChart.js",
3. Execute the JavaScript function "jet.picto.init" providing two parameters, the regionId of the DIV and the (internal) identifier of the PL/SQL ajax function.

The contents of the JavaScript file is :

! function (jet, $, server, util, debug) {
    "use strict";
    requirejs.config({
        baseUrl: apex_img_dir + "oraclejet/js/libs",
        paths: {
            "jquery": "jquery/jquery-2.1.3.min",
            "jqueryui-amd": "jquery/jqueryui-amd-1.11.4.min",
            "ojs": "oj/v2.0.0/min",
            "ojL10n": "oj/v2.0.0/ojL10n",
            "ojtranslations": "oj/v2.0.0/resources",
            "promise": "es6-promise/promise-1.0.0.min"
        },
        shim: {
            jquery: {
                exports: ["jQuery", "$"]
            }
        }
    }), jet.picto = {
        init: function (pRegionId, pApexAjaxIdentifier) {
            require(["ojs/ojcore", "jquery", "ojs/ojpictochart"], function (oj, $) {
                server.plugin(pApexAjaxIdentifier, {}, {
                    success: function (pData) {
                        $(pRegionId)
                            .ojPictoChart(pData);
                    }
                });
            });
        }
    }
}(window.jet = window.jet || {}, apex.jQuery, apex.server, apex.util, apex.debug);
// To keep ThemeRoller working properly:
define("jquery", [], function () {
    return apex.jQuery
});

The first function call (requirejs.config) is again the same is we did earlier. Please note that the paths mentioned in here might differ in your environment. You could define those paths as (Application level) Component Settings, but for simplicity I keep them hardcoded in this example.
Notice there is a "jet" namespace defined and within that namespace a nested "picto" namespace. So we could easily extend this file (after renaming it) to other chart types. The "init" method defines the required files and then calls apex.server.plugin passing the PL/SQL ajax function as a parameter. After this ajax function is called, the result - a JSON object - is passed to the ojPictoChart function.
On the last line, as Kyle Hu correctly commented in my previous post, we have to define jquery in order to make ThemeRoller work (again).
So in fact, the JavaScript is very straightforward: in the end just an ajax call passing the result into the ojPictoChart function.

So what is the magic of the last piece, the ajax PL/SQL function? Here it is::

function ajax
( p_region    in  apex_plugin.t_region
, p_plugin    in  apex_plugin.t_plugin 
) return apex_plugin.t_region_ajax_result
is
  c       sys_refcursor;
  l_query varchar2(32767);
begin  
  l_query := p_region.source;
  open c for l_query;
  apex_json.open_object;
  apex_json.write('items', c);

  -- add settings
  apex_json.write('animationOnDisplay' , p_region.attribute_01);
  apex_json.write('columnCount'        , p_region.attribute_02);
  apex_json.write('layout'             , p_region.attribute_03);

  apex_json.close_object;
  return null;
end ajax;

Thus it just takes the region source - a SQL statement -, executes it returning a JSON object. And to these results three of the available options, defined as plugin attributes, are added. Again, as simple as possible. So no validation on the correctness of the SQL (as all APEX Developers can write a correct SQL statement, right). And just a minor part of the available options are exposed in the plugin.

When you create a region based on this plugin you have to provide it with a correct SQL statement - one that will return a valid JSON object according to the pictoChart docs. For example:

select ename||' - '||job||'@'||dname "name"
,      'human' "shape"
,      1 "count"
,      case job
       when 'PRESIDENT' then 'black'
       when 'ANALYST'   then 'blue'
       when 'CLERK'     then 'green'
       when 'MANAGER'   then 'red'
       when 'SALESMAN'  then 'yellow'
       end "color"
from   emp
       join dept on emp.deptno = dept.deptno
order by 2 desc, 4

And if you set the settings as :


You'll get as a beautiful result:
So knowing this, it wouldn't be hard to rebuild the plugin by yourself. But for the lazy readers out there, you can download it here too.
Or probably build another plugin for another JET component!

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