Apex Tutorial - Form & Report sharing the same page

Apex Tutorial - Form & Report sharing the same page

Oracle Application Express - New Features in Release 4.1

Oracle Application Express
New Features in Release 4.1
	Error Handling Release 4.1 includes improved error handling and user-defined exception processing. You can now easily capture error messages generated by the Oracle database and replace the message text with user friendly text. For example, instead of an error message such as "ORA-00001 unique constraint (EMP_UK) violated" the developer can define a message such as "Employee Name must be unique".

Use of ROWID Application Express now supports the use of ROWID for updates, inserts and deletes as an alternative to specifying primary keys. Previously you could only specific two primary key columns. Therefore, if your table had more than two key columns then you could not use the default DML processes and had to manually write your own processes. Use of ROWID is now the default method for any new DML processes generated.

Data Upload Developers can now easily add the capability for end-users to load spreadsheet data into existing tables within an application. The developer can utilize a wizard to create a collection of pages that allow the end user to upload a file or cut and paste data into a table. Additionally the developer can define lookup columns and data transformations. End users are then led through a runtime wizard which allows them to load the data, map the columns, see whether the data will be inserted or updated, and review the results.

Calendar The calendar wizards have been enhanced to include the ability to create an Edit page as part of creating the calendar. Further calendars can now include drag and drop functionality which allows the end user to change the date and or time of a record by simply dragging it on the calendar itself.

Websheets Building on their initial introduction in Release 4.0, the look and feel of Websheets in Release 4.1 has been substantially improved and the controls redesigned to make it more intuitive for users. There are also new page section types, and enhanced data grid integration. Learn more >

Tabular Forms Tabular Forms now support all validation types. Depending on the validation type you can use bind variable syntax, substitution syntax, or just specify the tabular form column name. These enhancements allow developers to declaratively define complex validations instead of having to perform extensive manual PL/SQL coding.

Plug-Ins Plug-ins enable developers to enhance the existing built-in functionality by writing PL/SQL components for various components. This release expands the plug-in functionality and introduces the ability to create plug-ins for authentication and authorization schemes. View and Download Plug-Ins >

Dynamic Actions Dynamic Actions allow developers to declaritively define client-side functionality, without needing to master JavaScript and AJAX. With this release, a number of enhancements were added including the ability to define dynamic actions for buttons and also use dynamic actions to set multiple item values.

	Accessibility Release 4.1 includes dramatic improvement in the HTML generated by the Application Express engine, together with accessibility improvements in existing themes and HTML templates.
Mobile Applications Release 4.1 includes a number of key improvements to improve support for mobile frameworks, including form rendering without HTML tables.

New Browser Security Attributes in APEX 4.1

Oracle Application Express (APEX) 4.1 added two new Browser Security attributes: Cache and Embed in Frames. The attributes can be found by navigating to Shared Components > Security Attributes > Browser Security (region). Clicking on the items’ labels reveals some great documentation. I couldn’t find any other documentation online to link to so I’ve copied the contents here for everyone to see:

Cache

Enabling the cache allows the browser to save the contents of your application's pages in its cache, both in memory and on disk. If a user presses the browser back button, the page will typically be loaded from the cache, not from the server. If the cache is disabled, the browser is instructed to not save page content and will request it anew from the server.
From a security perspective the cache should be disabled, so the browser does not store sensitive data and will always request pages if the URL changes. Otherwise, it may even be possible to go back in the browser history after a logout and see cached content of the former session.
Disabling the browser cache will also prevent subtle back button issues with pages that use partial page refreshes for example pages with Interactive Reports.
If this item is set to "Disabled", Application Express will send the HTTP header cache-control: no-store which instructs the Browser to not cache the page contents on disk or in memory.
Note: This feature requires modern browsers that support the HTTP header response variable "cache-control".

 
Embed in Frames 

Use this attribute to control if the browser is allowed to display your application's pages within a frame:

• Deny: The page cannot be displayed in a frame, regardless of the site attempting to do so.
• Allow from same origin: The page can only be displayed in a frame on the same origin as the page itself.
• Allow: The page can be displayed in any frame.

Displaying pages within frames can be misused with "clickjacking" attacks, when an attacker uses multiple layers to trick a user into clicking on a button or link on another page when they were intending to click on the the top level page. Thus, the attacker is hijacking clicks (and/or keystrokes) meant for their page and routing them to another page.
Note: This feature requires modern browsers that support the HTTP header response variable "X-Frame-Options".

The Embed in Frames attribute was preventing the plug-in from working correctly - it was set to “Deny”. As the plug-in uses iframes, this attribute’s value must be set to either “Allow from same origin” or “Allow”. After upgrading to APEX 4.1, existing applications will be set to “Allow” but new applications will be set to “Deny”. Perhaps “Allow from same origin” would have been a better choice for the new default?
At the end of the day, the new Cache and Embed in Frames security attributes are very powerful in that they can help make your applications more secure with very little investment. Also, the additional benefits of the Cache feature sound great. However, developers should be mindful of the impact these attributes can have on their applications. Always test!

Generating random numbers and strings in Oracle

Do you know how to auto generate random numbers or strings in Oracle? Generating random numbers is required when there is a need to create a lot of data for testing purposes, or when we simply need to use a number to temporarily tag a process. It may also be necessary to generate random password strings of a fixed size--a very common requirement for websites that create and maintain logins for users.

Whatever the need, the fact is that Oracle provides us with a random number generator. This option is faster than writing your own random generation logic in PL/SQL as Oracle's internal processing logic is used. In addition, it can also be used to generate both character and alphanumeric strings.

DBMS_RANDOM package

The DBMS_RANDOM package will generate random data in character, numeric or alphanumeric formats. The size and the range from which to pickup the random values can also be specified. This package is created by the script dbmsrand.sql available in the <ORACLE_HOME>/rdbms/admin directory.

The following functions present in the package can be used to serve the purpose of generating random numbers and strings. RANDOM - generate random numbers.

VALUE - generate random numbers from the range provided. The range will be taken as 0-1 if none is provided.

STRING - generate strings in upper case, lower case or alphanumeric format.

• The first parameter takes the string type to be generated, the following values can be provided in upper or lower case.
• U - Upper case
• L - Lower case
• A - Alphanumeric
• X - Alphanumeric with upper case alphabets.
• P - Printable characters only. Providing any other character will return the output in upper case only.
  The size of the string should also be provided as the second parameter.

Oracle documentation says that it is necessary to initialize the package before using the random number generator. Oracle by default initializes the package with the seed value as the current user name, current time down to the second and the current session id.

INITIALIZE - Initialize the package to proceed with the number generation.

Provide a number (seed) as input to the routine.

SEED - Used to change the seed value. It is used in the internal algorithm to generate values. Setting this will

generate the random numbers in an order that will be similar in multiple sessions. Refer to the example below.

TERMINATE - Close the process of random number generation.

Examples:

Below are some examples of using the package.

E.g.: Generating a random number (positive or negative)

SQL> select dbms_random.random from dual;

       RANDOM
_____________
   1393936551

E.g.: Generating a random number between 0 and 1.

SQL> select dbms_random.value from dual;

        VALUE
_____________
            1

E.g.: Generating a random number from a range, between 1 to 1000.

SQL> select dbms_random.value(1,1000) num from dual;

          NUM
_____________
          611

E.g.: Generating a 12 digit random number.

SQL> select dbms_random.value(100000000000, 999999999999) num from dual;

          NUM
_____________
 175055628780

E.g.: Generating an upper case string of 20 characters

SQL> select dbms_random.string('U', 20) str from dual;

STR
_______________________
VUOQOSTLHCKIPIADIZTD

E.g.: Generating a lower case string of 20 characters

SQL> select dbms_random.string('L', 20) str from dual;

STR
____________________
xpoovuspmehvcptdtzcz

E.g.: Generating an alphanumeric string of 20 characters. There is a bug in Oracle 8i that results in special (non-alphanumeric) characters such as ']' in the string. This is resolved in Oracle 9i.

SQL> select dbms_random.string('A', 20) str from dual;

STR
__________________
sTjERojjL^OlTaIc]PLB

E.g.: Generating an upper case alphanumeric string of 20 characters

SQL> select dbms_random.string('X', 20) str from dual;

STR
________________________
SQ3E3B3NRBIP:GOGAKSC

E.g.: Generating a string of printable 20 characters. This will output a string of all characters that could possibly be printed.

SQL> select dbms_random.string('P', 20) str from dual;

STR
___________________
*Yw>IKzsj\uI8K[IQPag

E.g.: Example for calling the dbms_random package and setting the seed for generating the same set of random numbers in different sessions. Please note that the same random numbers are generated in different sessions. Though I have found this to work on most accounts, in some cases, the first number generated was different in different sessions and the remaining were same. I recommend not using this option in any of production code until it is properly document by Oracle.

jaJA>declare
  2     l_num    number;
  3  begin
  4    l_num := dbms_random.random;
  5    dbms_output.put_line(l_num);
  6    dbms_random.seed('amar testing 67890');
  7    l_num := dbms_random.random;
  8    dbms_output.put_line(l_num);
  9  end;
 10  /
483791552
478774329

PL/SQL procedure successfully completed.

Conclusion

DBMS_RANDOM is a good utility and will find its way into lot of development projects, especially web based ones. However, this Package is not exhaustively documented. One should not use it just for the sake of it being there. Make sure that there is a true requirement or a necessity of random values before making use of this package. If you already have a custom code meant for the same purpose, check out the benefits that are available when using this package compared to your application.

The Principles of Good Programming

The principles of good programming are closely related to principles of good design and engineering. The following programming principles have helped me over the years become a better programmer, and I believe can help any developer become more efficient and to produce code which is easier to maintain and that has fewer defects.
DRY - Don’t repeat yourself. - Probably the single most fundamental tenet in programming is to avoid repetition. Many programming constructs exist solely for that purpose (e.g. loops, functions, classes, and more). As soon as you start repeating yourself (e.g. a long expression, a series of statements, same concept) create a new abstraction.
http://en.wikipedia.org/wiki/Don%27t_repeat_yourself
Abstraction Principle - Related to DRY is the abstraction principle “Each significant piece of functionality in a program should be implemented in just one place in the source code.”
http://en.wikipedia.org/wiki/Abstraction_principle_(programming)
KISS (Keep it simple, stupid!) - Simplicity (and avoiding complexity) should always be a key goal.
http://en.wikipedia.org/wiki/KISS_principle
Avoid Creating a YAGNI (You aren’t going to need it) - You should try not to add functionality until you need it.
http://en.wikipedia.org/wiki/YAGNI
Do the simplest thing that could possibly work - A good question to ask one’s self when programming is “What is the simplest thing that could possibly work?” This helps keep us on the path towards simplicity in the design.
http://c2.com/xp/DoTheSimplestThingThatCouldPossiblyWork.html
Don’t make me think - This is actually the title of a book by Steve Krug on web usability that is also relevant in programming. The point is that code should be easily read and understood with a minimum of effort required. If code requires too much thinking from an observer to understand, then it can probably stand to be simplified
http://www.sensible.com/dmmt.html
Open/Closed Principle - Software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification. In other words, don't write classes that people can modify, write classes that people can extend.
http://en.wikipedia.org/wiki/Open_Closed_Principle
Write Code for the Maintainer - Almost any code that is worth writing is worth maintaining in the future, either by you or by someone else. The future you who has to maintain code often remembers as much of the code, as a complete stranger, so you might as well always write for someone else.
A memorable way to remember this is “Always code as if the person who ends up maintaining your code is a violent psychopath who knows where you live.”
http://c2.com/cgi/wiki?CodeForTheMaintainer
Principle of least astonishment - The principle of least astonishment is usually referenced in regards to the user interface, but the same principle applies to written code. Code should surprise the reader as little as possible. The means following standard conventions, code should do what the comments and name suggest, and potentially surprising side effects should be avoided as much as possible.
http://en.wikipedia.org/wiki/Principle_of_least_astonishment
Single Responsibility Principle - A component of code (e.g. class or function) should perform a single well defined task.
http://en.wikipedia.org/wiki/Single_responsibility_principle
Minimize Coupling - Any section of code (code block, function, class, etc) should minimize the dependencies on other areas of code. This is achieved by using shared variables as little as possible. “Low coupling is often a sign of a well-structured computer system and a good design, and when combined with high cohesion, supports the general goals of high readability and maintainability”
http://en.wikipedia.org/wiki/Coupling_(computer_programming)
Maximize Cohesion - Code that has similar functionality should be found within the same component.
http://en.wikipedia.org/wiki/Cohesion_(computer_science)
Hide Implementation Details - Hiding implementation details allows change to the implementation of a code component while minimally affecting any other modules that use that component.
http://en.wikipedia.org/wiki/Information_Hiding
Law of Demeter - Code components should only communicate with their direct relations (e.g. classes that they inherit from, objects that they contain, objects passed by argument, etc.)
http://en.wikipedia.org/wiki/Law_of_Demeter
Avoid Premature Optimization - Don’t even think about optimization unless your code is working, but slower than you want. Only then should you start thinking about optimizing, and then only with the aid of empirical data.
"We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil" Knuth.
http://en.wikipedia.org/wiki/Program_optimization
Code Reuse is Good - Not very pithy, but as good a principle as any other. Reusing code improves code reliability and decrease development time.
http://en.wikipedia.org/wiki/Code_reuse
Separation of Concerns - Different areas of functionality should be managed by distinct and minimally overlapping modules of code.
http://en.wikipedia.org/wiki/Separation_of_concerns

jQuery Mobile - Anatomy of a Page

Anatomy of a Page

The jQuery Mobile "page" structure is optimized to support either single pages, or local internal linked "pages" within a page.
The goal of this model is to allow developers to create websites using best practices — where ordinary links will "just work" without any special configuration — while creating a rich, native-like experience that can't be achieved with standard HTTP requests.

http://jquerymobile.com/demos/1.0a4.1/#docs/pages/docs-pages.html

Oracle Application Express 4.1 Early Adopter is now available

On Friday 06.05.2011 the APEX Development Team had a Surprise for us: they published the first Early Adopter Version of Oracle APEX 4.1

 

Oracle Application Express 4.1 Early Adopter is now available
Click here to access the hosted site.
Our statement of direction is available here.

 

 

Oracle Application Express 4.1

Oracle Application Express 4.1 will focus on enhancement to existing functionality and additional capabilities to support applications running on mobile devices. Application Express 4.1 is planned to incorporate the following:

• Development for Mobile Applications – Include themes and HTML templates suitable for smart phones and mobile devices.
• Error Handling - Improve error handling and user-defined exception processing.
• Tabular Forms – Continue to expand tabular forms validations.
• Dynamic Actions – Allow dynamic actions to be defined for buttons and enhanced conditional processing.
• Plug-Ins - Add plug-in support for additional components and enhance plug-in definitions.
• Use of ROWID – Allow usage of ROWID for Automatic DML processing (as an alternative to identifying the PK columns).
• Websheets – Improved user interface, new page section types, and enhanced spreadsheet / datagrid integration.
• Data Upload - Enable end-users to upload data into an existing table (within an application).
• Accessibility – Improve accessibility in existing themes and HTML templates.
• Numerous functional and performance improvements.