Tuesday, 25 June 2013

Using jQuery for Drag and Drop

Recently I wrote a blog on how to use drag and drop (DaD) in your APEX application. Unfortunately the javascript I used didn’t work in all browsers. I found a solution using jQuery UI. I’ve modified the code in my example application and now DaD seems to be working on all major browsers. First thing that I’ve noticed was that the draggable table cells needed to be in the same region as the droppable form cell. So I’ve made one region with both the form on the emp table and the report on the jobs table.

Then, to make the table cells draggable I had to change the classes added to the table cells. The page load dynamic action now looks as follows:

The job form cell (P8_JOB) had some classes added to it, but in this jQuery setup that was no longer necessary. I’ve removed them from the ‘HTML Form Element Attributes’. The last step was to add the draggable and droppable functions in the page header. Two jQuery libraries had to be added:

Then all table cells with class “.job ” are being made draggable and Th P8_JOB page item is made droppable to receive a draggable element, and the P8_JOB item is given the value of the job cell that is dragged into it.

The result is more robust then my previous example, since it is now supported by all major browsers (assuming that your browser is up to date). This browser compatibility can be quite a problem since when working with HTML5 and/or JavaScript. It seems jQuery is better supported then conventional JavaScript. This website can be quite helpful to find out if the HTML5 you’re trying to use is supported by your browser (kudos to Elie for bringing the side under my attention).
You can check the working example here. Again, have fun.

Sunday, 23 June 2013

Applying Drag and Drop in an APEX Form

Today I was asked if you can use drag and drop functionality in APEX. I figured APEX shouldn’t be the problem, but I had to look into the exact implementation. In this blog I will share my findings with you.

Drag and Drop (DaD) is a HTML5 feature, like other HMTL5 features there’s nothing in APEX preventing you from using them. However, your browser must be HTML5 compatible and, in this case, support DaD. For a listing of compatible browsers check here. DaD consists of triggering- and receiving elements. An element that is dragged can trigger the following events (thanks to netmagazine):

  • dragstart: triggered when dragging a draggable element
  • drag: triggered by moving the draggable element
  • dragend: triggered by dropping the draggable element
Elements that receive draggable elements can trigger the following events:
  • dragcenter: triggered when a draggable object is dragged over an element
  • dragleave: triggered when a draggable object is dragged outside of an element
  • dragover: triggered when a draggable object is move inside an element
  • drop: triggered by dropping a draggable object.

In the following example I will show a form on the EMP table in which you can update the JOB column by dragging a job role into the JOB form field. The first step is to create a form; I chose to make a form on report. On the form page I’ve added a standard report with the various job roles that can be selected. For this example I created a table “JOBS”, which holds the various job roles.

If we want to be able to drag the various job roles, we need to make them “draggable”. Also, for further handling, I want each job/table cell to have an ID. I add them with a dynamic action that fires on page load.

The function in the dynamic action loops trough each table row of report_jobs – the ID of the JOBS report table- and adds a the following items

  • a class “job”;
  • an attribute “draggable” set to “true”, this will make it possible to drag the table cell around the screen;
  • an attribute “ondragstart” , which will trigger a function “dragJob”;
  • an ID to uniquely identify each table cell. Here the id will be set to the job role in that cell.

Next we need to tell the JOB item in the form that it can receive draggable items. To do so I’ve added the following attributes:

So now we have a report table with jobs, each job we can drag around the screen, and we have a page item that can receive a draggable element. Now to actually set the page item with the value of the dragged job, we need two functions. For simplicity I’ve added them to the page HTML header.

The first function is started as soon as you start dragging an element. The element’s id is set to the dataTransfer.

The second function is started when you drop the element in the page item and will assign the value of the dragged table cell to the page item.

And that’s about all there’s to it. To view a working example, please visit my demo application: In the interactive report click on the edit link of an employee and then in the form try to set the change the job of an employee by dragging a job from the jobs report. So as you can see, with a few simple steps you can create DaD functionality to your APEX application. Please bear in mind that your browser needs to be HTML5 compatible and that this example is simplified as an example. However, when used properly your application can benefit from DaD by making it more intuitive and interactive.
Good luck!

Saturday, 15 June 2013

Integrate JasperReports in your application and manage security

In a previous blog I explained why I think JasperReports is such a great report engine to use alongside your APEX application. In this post I would like to explain how you can integrate JasperReports in your APEX application and how you can manage a security. Since the installation of reports library is well documented by JasperReports self and since the exact install instructions depend on your setup, I will not go into explaining the installation. Instead I will take as a starting point a situation where you have a server with one or more APEX applications and a JasperReports engine.

With JasperReports you can call a report over the URL, the URL would typically look something like:

As you can see all details regarding the report you’re requesting are passed over the URL, including output format and data source. If your report would require additional parameters (for example for the where-clause of your report query), they could simply be added by extending the URL with &=:

Now to call a report from your APEX application, you could add a button with a link to the report URL. Unfortunately, this would not be really flexible. Another problem would be that your URL is visible for everyone who has access to your application.

A more dynamic way would be to create a procedure that builds the url for you, based on parameters that you can define and manipulate on your APEX page. You can base your procedure on the HTTP-UTIL package. Fortunately, such a package already exists. It is a free to use integration package, made by Dietmar Aust from Opal Consulting. With that package installed in your database, you can create the report URL with a page process. With the process calling the report, the URL is no longer visible on your page; therefore your report localities are not immediately disclosed.

So now we have a way to hide the URL, but the report can still be reached once someone somehow manages to create the URL himself. As explained on the Opal Consulting website, you can easily create an extra security layer by using a firewall. That way only the APEX engine can call the report engine and your report can no longer be called over the URL directly.

A last security step that you can add is verification on session id. In APEX active sessions are stored in a table (WWV_FLOW_SESSION$). The table self cannot be queried directly, instead you can use the ‘APEX_WORKSPACE_SESSIONS’ view. By adding a where clause to your report query, you can validate whether the calling apex session is an active one.

As I’ve shown in this blog, you can secure your application’s reports with a few simple steps. Hiding the calling URLs is a first and in my opinion essential step if you want to secure your reports. If you have the possibility, firewalling the report engine is strongly recommended. If that is somehow not an option, or if you want to take security a step further, you can consider validation on session id to prevent unauthorized report calls.

Sunday, 9 June 2013

Apex and JasperReports: printing reports

APEX is a great tool for web application development. It’s fast, and easy to learn, on top it’s highly flexible. That being said, APEX has no native method for printing reports from your application. Instead you can connect a print server to let you handle your report printing.

The reason that the APEX development team didn’t create a build in print server seems to be that it is beyond the focus of the APEX project. Besides, Oracle already has BI publisher as print server. Another reason could be that building a native print server would likely require the use of Java. That would be a problem with Oracle XE that does not support Java in the database. So the choice of supporting other print servers instead of building a native one makes sense. It does of course; raise the question what tool to use for printing reports?

Oracle has its own reporting tool: BI publisher. With the help of a browser interface or an IDE you can easily build documents and reports, schedule mailings, etc. The downside is that it’s not license free. Fortunately APEX is distributed with another print server: Apache FOP (Formatting Objects Processor). FOP is a print formatter that uses XSL –FO, which are XML like templates that determine the layout and output of the report. The data is delivered in a XML document. Unfortunately, building the XSL and XML files is a complex and time consuming process, which will likely result in high development costs.

An alternative reporting tool is JasperReports, an open source reporting engine by Jaspersoft. The print server takes data from virtually any data source and translates them into high quality, printable reports. You can easily build reports with an IDE of choice: iReport -a Netbeans-based designer, or Jaspersoft Studio –an Eclipse based designer. Best of all: it is cost free! That is, there is a very functional community edition that lets you build any type of printable report you can imagine. You call a report with an URL that contains your data source, and – if your report query requires so – the parameters to build your query. Basically in the same manner as APEX calls an application page (although the syntax is rather different).

The fact that it is easy to use and allows for rapid development, along with the fact that the print request is comparable with the way APEX transmits page calls, makes JasperReports the ideal reporting tool to incorporate in your APEX application. An added benefit is that the print server along with the IDE are cost free (community edition). In an upcoming blog I will go further into incorporating JasperReports into your APEX application and building a secure interface.

To get started with JasperReports, please visit the Jaspersoft website; there you can also download iReport or Jaspersoft Studio. To download JasperReports, go here. If you want additional information on JasperReports, iReport, or if you’re looking for installation instructions, you can look here.

Tuesday, 4 June 2013

Manipulate multiple tables from one tabular form

A tabular form enables you to process a number of rows in one go. On page submit all changed records of the tabular form will be inserted, updated or deleted from the subjected table.

Up until now there is a restriction, though: you can put only one tabular form on a page (apparently Apex 5.0 will let you use more than one tabular form on a single page). The reason for this restriction has to do with the way Apex processes tabular forms. There are however, various workarounds to this restriction. One such workaround is to use one tabular form to manipulate more than one table. In this post I will demonstrate how to create such a tabular form.

We will manipulate more than on table, for this we need to create a view that contains all the columns of the tables that we want to manipulate. This itself is straight forward and enables us to query records from multiple tables. However, it doesn’t let us perform inserts, updates or deletes. For that we need “instead-of-triggers” . Instead of triggers enable us to do inserts, updates and deletes on a view, i.e. to perform dml on the underlying tables.

Now we have multiple tables, joined in one view, which we can manipulate with one tabular form. Unfortunately, all columns of the view are visible in the tabular form, while they don’t belong to the same tables. To make sure that when running the page you only see the right –the for that time appropriate- columns, we need to give the columns a conditional display. You can set the conditional display with ‘edit page item’ > ‘conditions’. Which columns should appear at what time is of course entirely dependent of what your page should be showing at any given time.

This is all you need for a simple workaround to manipulate more than one table from a single tabular form. Note however that tabular forms rely heavily on rowids. This can be a problem, especially with views. To secure your page from processing, you could remove the Apex-generated page processes and replace them with your own procedures.

Good luck!

Custom multi row processing using tabular form

In this post I will explain how you can perform a custom function or procedure on multiple rows in a tabular form. In APEX, a tabular form lets you do multiple inserts or deletes using the ‘MULTI_ROW_INSERT’- and ‘MULTI_ROW_DELETE’-buttons. You can also do updates on multiple records, but you need to alter each record individually. Doing the same update routine on a number of records, would require you to set each new value by hand, before doing the submit. Wouldn’t it be great if you can do an update on multiple selected rows in one page submit? In the following example I will show you how you can update the salary of a number of selected employees. The example consists of a tabular form on the standard ‘EMP’ table.
On the tabular form page I’ve put a hidden item to store the primary key values of the selected rows, in this case ‘EMPNO’.
To fill the page item with the primary key values of the selected rows, I use a dynamic action. The dynamic action will fire on every change in the tabular form region. This way every time you check or uncheck a checkbox, the dynamic action will evaluate which rows are selected.
Using jQuery, I fetch the selected values. Note that I concatenate  all the values to one string delimited by a colon.
In my example I perform the update routine as a page submit, so I need two more things:
  • a region button to submit the page
  • an after submit page process. 
The button is in this case a standard button that performs a page submit, here I’ve called the button ‘RAISE_SAL’. Last, in the after submit process, I will do the actual update of the employee salaries. The selected employees will get a standard raise of ten percent. In the page process I use the ‘APEX_UTIL.STRING_TO_TABLE’ function to put the concatenated EMPNO’s into an array.  In the loop the ‘SAL’-column of the EMP table is updated for all the EMPNO’s from the array.
And that wraps it up. Now you have a tabular form with which you can update multiple rows with the same update routine in one go. To see a running version of the above example, click here. Enjoy!