Tuesday, 30 July 2013

Detail section in line with report, part 2

In my previous post I explained how you can display a details section within an (interactive) report. The solution relied on using an iframe to display a detail report or –form on another page and on jQuery to display or hide the details. This solution works great in some cases, but it has a few shortcomings. In this post I will discuss two of the most apparent problems.
The first big problem arises when we use session state protection. Session state protection prevents unauthorized manipulation of the URLs within your application. The session state protection creates a checksum that is appended after each page URL, without a valid checksum you can’t navigate through your application. In our setup thus far we could simply create the URL for the iframe that holds the report details. With session state protection enabled, we need to find a solution to create a valid checksum that we can use in our URL.
The apex_util package has a function, prepare_url, that takes your URL as parameter and returns you the same URL extended with a checksum. This requires us to use pl/sql, and our URL is created in a jQuery dynamic action. What we’re going to do is remove the URL from the dynamic action and instead add it as a column to the report query, using the prepare_url function.
Since we don’t need to display the URL in our, but we do need to be able to find it with JQuery, we give the report heading a simple span as title and de “Display as” attribute we set to “Standard Report Column”. In the column link section we set the “Target” attribute to “URL” and the “URL” attribute to “#DET_LINK#” – this is a substitution of the column name we gave the prepare_url column in our report query.
Now that we have our URL ready, we need to modify our dynamic action. The URL to the details section of each row can be reached with But note that the iframe needs the url domain prepended whereas the prepare_url function doesn’t . Also, now that we have the URL ready, we don’t need the variables for application id and session id, so we remove them from the dynamic action. The code no looks as follows:
With these changes we have a working report and iframe again, this time with session state protection.

The second issue I’d like to discuss is partial page refresh. Partial page refresh reloads a region of your page, without submitting or reloading the entire page. This is really handy, says when You use a modal page to update or modify the details of our your report and you want to immediate show those changes. Unfortunattely, the refresh of the region unbinds our jQuery function that opens and closes the details, so we can no longer show details until we reload the entire page. To better show this issue I’ve changed the detail report in the example application to a tabular form that lets you make some changes to the emp table.
To better display the and control the tabular form, we add a hidden item ‘READONLY’ that we will set to ‘Y’ from our report url link, so that when we open the form as an iframe the item will be ‘Y’. We add a page load dynamic action on the tabular form page that will hide and DISABLE! The page buttons and will disable the form fields.
Also we add a modal page to edit the EMP table. For this we can use the Modal Page plugin from Skillbuilders, that’s an easy and flexible plugin that lets you make a modal page in just a few clicks.
Now it is important to remember that we had session state protection enabled, so the modal page attribute “Static URL” must get an URL with a checksum. To do this, we can a hidden item, here TEMP_URL and set it’s source with a pl/sql expression. As expression we again use the apex_util.prepare_url function. We create a buttton to fire the dynamic action.
At this point we have a page with a modal page that we can use to update the EMP table and an iframe that we can use to display the employees per department. To immediately show the changes we make in the modal page, we add a refresh action on report region. We let the refresh take place after we click on the close button of the modal page.
Because the refresh of the report unbinds the dynamic action that controls the display of the report details, we need to find a way to rebind the dynamic action. At this point it might be a wise dissision to avoid a growing number of dynamic actions, and move our jQuery function to a seperate js file. In a file it is also rather easy to control the rebinding of the function after the report region refreshed.
In our js file we have two functions. One is the click function we already have, the other is a function that adds a class to each row in the dept report. That function needs to be rebinded after the region refresh. The code in our file looks like this:
We add the file to our page by uploading it in shared components > static files. In our page we can add the file in the page settings under the JavaScript section. We can reference the file library with the #APP_IMAGES# substitution.
At this point we have all we need. The dynamic action that controlled the display of the details section is now covered by the JavaScript file, so we can delete the dynamic action. By now our report is working as we expect it to and it can handle session state protection and partial page refresh.
to see a working demo watch my demo application.

Saturday, 20 July 2013

Show report details in line

The other day I needed to create a report which could dynamically show and hide details of a row. I have seen examples before where either a pl/sql region was used or a function returning the required details was being used. In both cases you have create a procedure or function that returns html based on a query. You have to think of a way to collect the required data and then wrap it in HTML divs, td, etc. The result is very elegant, but the setup is rather time consuming. That can be worth the while if you can reuse that code on other reports in your application.
Unfortunately, in my case I only needed to show details in one report. To make it more complex, the details that I needed to show were subject to debate. It was likely that the exact details that needed to show were going to change during the development of the application. Therefore I chose a swift and simple solution based on jQuery and iFrames.
In the following example I will reconstruct what I’ve done, based on the DEPT and EMP tables. The result is a report on DEPT, which, as detail, shows all the employees of a department. We’ll make two pages, one for the DEPT report and one for the EMP report, which will be displayed in line in the DEPT report. Let’s start with the latter.
We need a page with a report on EMP. We only want to show the employees of the department we select in the DEPT report, so we need to add a where clause in the report query, and we need to add a page item that we can set. Here, I’ve created a hidden item calls ‘DEPTNO’.
The report query needs to be modified: we add a where clause that takes DEPTNO as a parameter
Just to make sure that our report shows up nicely as a detail, we will select page and report templates with little style features. Here I used “Popup” for page template and “No Template” for the report region. Also I’ve added a “nowrap” style element to the region header; this will ensure that the report columns will not break in two lines when the content gets to wide.
That’s all for the employee details. Now we’ll go to the DEPT page. Here too we create a page with a standard region, this time on the DEPT table.
On this page we need to create a dynamic action that will control the display and hide of the employees’ details. Here I’ve created a page load JavaScript action.
What the function does is as follows. When we click on a row, we check if we are already showing the details for that row. If we don’t we’ll create the URL of the employee page and put it in an iFrame. That iFrame we’ll wrap in a table row and paste it right after the row we clicked on. Else, if we already have the details for that row, we close the details section. The code is as follows:
And that's all. No we have a report showing all departments. When we click on a row we get a detail report of all the employees in that department. When we click the row again the detail closes. The great benefit of this setup is that we can easily change the way our detail section looks by simply modifying the report on employees.
See how it works in my sample application.
Good luck.

Sunday, 7 July 2013

Understanding APEX URL synax

A good understanding of the way APEX uses URL’s helps you to easily navigate through your applications. It’s also helpful for version control and maintenance. In this post I will highlight the key features of the APEX URL syntax, complete documentation on the URL syntax can befound here

The URL consists of a static part for the domain and DAD, and a dynamic part, consisting of an number of colon delimited parameters. A typical APEX URL looks like: http://apex.oracle.com/pls/apex/f?p=42742:8:100133297155888::NO::P8_ROWID:ABSCZ%2FAE7AAAACVAAD This URL encloses information for navigation (to the coorect page) as well as identification and a bunch of other info as well. To break it down the URL consists of the following parts:

To link between pages in your application you can use an URL to has the following parameters

The following table describes all the parameters in the URL:

Syntax Description
App The application ID or the application alias
Page The page ID or the page alias
Session Identifies a session ID. You can reference a session ID to create hypertext links to other pages that maintain the same session state by passing the session number. You can reference the session ID using the syntax:
Request Sets the value of REQUEST. Each application button sets the value of REQUEST to the name of the button which enables accept processing to reference the name of the button when a user clicks it. You can reference REQUEST using the syntax:
Debug Displays application processing details. Valid values for the DEBUG flag include: Setting this flag to YES displays details about application processing. Setting this flag to LEVELn (where n is between 1 and 9) controls the level of debug detail that displays. The value of YES equals LEVEL4. You can reference the Debug flag using the following syntax:
ClearCache Clears the cache. This sets the value of items to null. To clear cached items on a single page, specify the numeric page number. To clear cached items on multiple pages, use a comma-separated list of page numbers. Clearing a page's cache also resets any stateful processes on the page. Individual or comma-separated values can also include collection names to be reset or the keyword RP, which resets region pagination on the requested page. The keyword APP clears cache for all pages and all application-level items in the current application and removes sort preferences for the current user. The keyword SESSION achieves the same result as the APP keyword, but clears items associated with all applications that have been used in the current session.
ItemNames Comma-delimited list of item names used to set session state with a URL.
ItemValues List of item values used to set session state within a URL. Item values cannot include colons, but can contain commas if enclosed with backslashes. To pass a comma in an item value, enclose the characters with backslashes. For example: \123,45\

Determines if the page is being rendered in printer friendly mode. If PrinterFriendly is set to Yes, then the page is rendered in printer friendly mode. The value of PrinterFriendly can be used in rendering conditions to remove elements such as regions from the page to optimize printed output. You can reference the printer friendly preference by using the following syntax:


When referenced, the Application Express engine does not display tabs or navigation bars, and all items are displayed as text and not as form elements.

The application- and page aliases, as well as the substitution strings for session, request and debug, are very handy for linking between pages, say when you want to use a button to redirect to another page in your application. They play a role in maintenance too.

The session ID is unique for each session, so if you put your session hardcoded in the redirecting URL, navigation will only work for your current session, the URL will be useless as soon as your session has expired. Using application and page aliases are helpful for example when you want to move your application from development to production. The application ID you used in the development environment might not be available in your production environment . So if all redirecting URL’s in your application have the application ID hardcoded, redirection will no longer work. Using an application alias solves this problem. The page alias is mostly helpful for creating understandable navigation. You can let your users navigate to a page called ‘home’, instead of page ‘1’.

To make your page even more independent of hardcoded values, you can consider replacing the ‘P_’ part of your page items by ‘_’ .doing so enables you to move your page within your application without losing navigation logic.