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Talk about it, inform your customers, prepare workarounds for the nasty ones and bugfixes/patches for everything else.

Oracle knows all this and provides a list of known bugs/issues with Oracle APEX 4.0.

If you encounter a bug which is not listed there, please report it in the forum (maybe using “Bug” or “Bugreport” in the Subject).

Don’t be shy, even if it turns out not to be a bug, you’ll definitely learn something :-)

Update:
Look at a very good example of how fast a bug can be solved as soon as it is reported.

A typical APEX URL looks like this:

http://tryapexnow.com/apex/f?p=2500:1:1016153158259880

That means:
open Application 2500 on Page 1 using Session 1016153158259880

But there can be much more…

Most of this stuff here is described very well in the Oracle Application Express Application Builder Users’s Guide, Chapter “Understanding URL Syntax“, nonetheless i try to explain it using my own words.

The complete APEX URL Syntax looks like this:

http://apex.oracle.com/pls/apex/f?p=AppId:PageId:Session:Request:Debug:ClearCache:Params:ParamValues:PrinterFriendly

Let’s take a closer look:

• http:// – the protocol, can be http or https
• apex.oracle.com – your domain/host/server, whatever you want to call it. Can also be localhost.
• /pls – indicates that you are using Oracle HTTP Server with mod_plsql. If you are using APEX Listener or Embedded PL/SQL Gateway this part is obsolete/missing.
• /apex – the entry from your dads.conf file (this a file on your application-server or EPG where the target database is configured) – in case of EPG its just one entry pointing to localhost, in case of an OAS you can have multiple entries, each pointing to an other database
• /f?p= – procedure “f” is called and parameter “p” is set to the complete rest of the string. Remember: APEX uses mod_plsql. “f” is a public procedure, this is the main entrypoint for APEX. Or you could say: “f” is APEX.
• AppId – the number or the Alias of the Application
• :PageId – the number or the Alias of the Page
• :Session – unique Session ID, can be 0 for Public Pages or empty (then APEX creates a new Session)
• :Request – a Request Keyword. This is basically free text, just a string you can specify to react in a process or region condition on. e.g. you could pass the keyword “CREATE” and have a condition on the delete button of your page saying “dont’t display this button if request is CREATE”.
  In other words: use the REQUEST to control the behaviour of your page.
  When pressing a button, the button sets the REQUEST to the button-value (e.g. SAVE), so that you can control the processes in the page processing (Submit) phase.
• :Debug – set to YES (uppercase!) switches on the Debug-Mode which renders debug-messages and timestamps in your Browser window. This helps to detect wrong behaviour of your page or performance issues and everything else. Every other value then YES turns the Debug-Mode off
• :ClearCache – you can put a page id or a list of page ids here (comma-separated) to clear the cache for these pages (set session state to null, …). But there is more: RP resets the pagination of reports on the page(s), a collection name deletes the collection, APP clears all pages and application-items, SESSION does the same as APP but for all applications the session-id has been used in.
• :Parameters – comma seperated list of page-item names. Good practice is to set only those page-items which are on the page you are going to. Accepts page-items as well as application-items.
• :ParamValues – comma separated list of values. Each value is assigned to the corresponding Parameter provided in ParamNameList (first value assigned to first parameter, second value assigned to second parameter, and so on…).
  The trick here is not having values which contain either a comma “,” or a colon “:”. Both would lead to side-effects and errors, as APEX gets confused when parsing the URL. Using a comma works, if enclosed by slashes: e.g. /123,89/.
• :PrinterFriendly – set to YES (uppercase!) switches the page into PrinterFriendly-Mode, uses the Printerfriendly template to render the Page. You can also hide regions or other elements in PrinterFriendly-Mode using the PRINTER_FRIENDLY variable in a condition.

There are also some more Blogs dealing with URL Syntax, take a look at some of them: MattsBits, Oraclenerd, Burleson .

Imagine a SQL Report Region (“Classic Report”) and a button next to it. In front of the computer is a nervous user who waits for a certain record to appear in his Report (e.g. this months salary in his bank statement).

So what is he doing? The nervous finger. Clicking the refresh button every 10 seconds. And everytime he clicks the button, the page is submitted and loads the new data. But this Page submitting and reloading takes some time and flickers, which makes our user even more nervous.

Better and faster would be refreshing the report without submitting the Page, looks smooth and totally Web 2.0.

APEX has a JavaScript function $a_report(pId,pMin,pMax,pFetched,pSort) which reloads the reports data and displays it without resubmitting the whole page.
pId is the ID of your Report, pMin and pMax are the RowIds to display, pFetched the number of Rows and pSort can hold some sort clause.

e.g. javascript:$a_report(‘15520013154312712′,’1′,’10′,’10′);

Now all you have to do is put this javascript call into your Buttons Target

And make sure that your Report is set to “Enable Partial Page Refresh”, this is needed to make sure that $a_report knows what to do.

Recently i switched from my old WinXP Notebook to a MacBook Pro and finally managed to set it up for all my working projects and my needs.

When working on ApexLib i often need different Versions of APEX to check the new features, which means multiple databases with each a different APEX Version on it.

My Requirement was to have multiple Virtual Machines, each of them with Oracle XE and APEX installed. The System Requirements shouldn’t be too high, so i decided to go for Linux in my VM’s and use Parallels Desktop as Virtualization Software.

On Parallels Homepage i found a ready prepared VM containing a stripped down linux (without desktop GUI, console only) with a basic Oracle XE installation on it. After downloading it all you have to do is start it.

Another important Requirement was that i needed fixed IP’s for my VM’s and my Mac, regardless which network i am currently connected to. Parallels has a networking option called NAT/Shared Networking for this kind of requirement, to set it up you open the Parallels Preferences and switch networking type to Shared and check the box saying “show in system preferences” and set the DHCP Range to a startpoint of 10.211.55.100.

In the System Preferences under Networking you choose the Parallels Networking Adapter and set its IP address to 10.211.55.101 (or whatever you want, this doesn’t make any difference).

Now open the Configuration of your Virtual Machine, go to Hardware -> Networking Adapter and set this to Shared Networking too.

For the last part start the Virtual Machine, press Alt+F2 to get to the login prompt and log in with root. On the console type “netconfig” and give your Virtual Machine a fixed IP-Address from the free Range before .100 which is your Gateway/DNS.

I chose 10.211.55.32 for APEX 3.2, 10.211.55.31 for APEX 3.1 and so on.
In the file /etc/hosts i added an entry for my Host Mac, so that i don’t need to remember the IP Addresses.

Finally edit the /etc/hosts file on my Mac and add host names for all your Virtual Machines.

Now reboot everything (i know, this isn’t needed but i’m a long time windows user….) and enjoy your little network, to open APEX on a certain machine simply use the before specified host-names, e.g. http://xeapex32:8080/apex

When displaying error messages in the notification area the rest of the page is shifted downwards a little. This is no problem most of the time, except in this case:

1. you have a form with required fields
2. you enter some of the fields and then realize you don’t want to enter more but leave the form
3. so you press the “Cancel” Button while your cursor is still in an empty required field
4. before the Cancel Button is processed the field validation displays the “Field is required” Message
5. displaying the Error shifts the button downwards, the mouse cursor isn’t hovering above the button anymore
6. the browser decides, that you clicked into empty space and discards Button processing

Long story short, you have to press the button a second time if an error message is displayed in the notification area when pressing the button.

I haven’t found any satisfying solution to avoid this problem in a programmatically way, so this leaves us with few options:

1. ignore it and let your users click a second time
2. have a fixed size notification area (this is kind of complicated, since you never know how many error messages you need to display)
3. my favorite: let the notification area hover above the rest of your form

Solution 3 can look like this, depending on your layout or used theme you’ll have to implement it in a different way.

See a working solution online in the Demo-Application.

All I had to do, was modifying the CSS Settings for the notification area:

.t7notification {
 background:none repeat scroll 0 50% #FFFFCC;
 border:1px solid #FFD700;
 color:#333333;
 font-size:11px;
 font-weight:bold;
 left:25%;
 margin:4px auto;
 opacity:0.8;
 filter:alpha(opacity=80);
 padding:2px;
 position:absolute;
 text-align:center;
 width:50%;
}

Looking for a certain application can be time consuming if you don’t remember what the workspace this application belongs to is called.

At this point you could either check the repository using a SELECT

SELECT *
  FROM APEX_APPLICATIONS
 WHERE APPLICATION_NAME LIKE '%XY%';

Or you could login into the administration section (workspace INTERNAL) and look there.

Way easier is having a listing of all applications right below the login fields:

This makes finding the right workspace faster and easier, having the listing of all applications in your database is like a directory listing of all your files you are working on.

Warning: Displaying information about your applications is a potential security risk, you should use this on internal development systems only, never on a public system!

How does it work?

As you may know, Oracle APEX is written in Oracle APEX. An APEX Builder page is just like any other page you  may design for your application. That means you easily can add a reports region to the login page.

The only downside here is that you can’t edit internal applications with the APEX Builder, you just can’t login to the INTERNAL workspace in edit mode.

But no need for that, we just use the same API that’s used in the Application export files.

Check out the script over here. It basically adds a reports region to the (english) login page, thats all.

Disclaimer: Enhancing/changing the internal applications may not be intended by Oracle, so there is no warranty at all. Whatever you do is own your own risk.
Go for it :-)

Before moving the data i had to ensure, that there will be enough space in the VARCHAR2 columns which were defined as VARCHAR2(255 BYTE).

That’s where my travel started, i had to figure out how many bytes a CLOB-Value would consume when storing in a VARCHAR2 column.

LENGTH(<clob-column>) fails, because it returns the number of characters

DBMS_LOB.getLength(<clob-column>) fails as well, because it returns number of characters

LENGTHB doesn’t work on CLOBs, so i thought: implicit type conversion, so i came up with this

LENGTHB(DBMS_LOB.SUBSTR(<clob-column>,1,2000)) this one looked promising, but it failed at the end because it would return the number of bytes this string uses in the CLOB Characterset (which is AL16UTF16)

The winner is: LENGTHB(TO_CHAR(SUBSTR(<clob-column>,1,4000))) this one really returns the size in bytes the string would consume when stored in a VARCHAR2 column.

Thanks to explicit type conversion!