Wednesday, 8 October 2008

Typos in my dads.conf (or Car chases, sex scenes and a dashing blogger)

Apparently Jerry Bruckheimer refuses to make any movie that cannot be summarised in six words (although lots of people would probably argue that most Jerry Bruckheimer movies can easily be summarised in a single four-letter word that starts with a 'c', ends with a 'p' and manages to squeeze an 'r' and an 'a' between them). In this respect, I guess, this blog is very much like a Bruckheimer movie - car chases, sex scenes, gunfight and a swashbucklingly handsome blogger - in that it can be summarised in 6 words: Apex is great because it's in the database. (Okay, make that 8 words.)

This is brilliant because it means that when I need to send my client an upgrade (version baby!) all I have to do is send them a file which they can run in SQL Plus. Except my last upgrade didn't work... Instead I got an error message saying that I needed to set something called a security_group_id. Huh?

I tried to import the application via Apex and my browser exploded (not literally, of course; I'm not really Jerry Bruckheimer).

The error I got was:

Mon, 06 Oct 2008 13:59:00 GMT

ORA-00942: table or view does not exist

DAD name: apex
PROCEDURE : wwv_flow.accept


It went on in a similar vein for a hundred more lines but what the hell did it all mean? ORA -00942 I understood (I've been an Oracle developer for so long that I see ORA numbers in my nightmares) and I could see that the procedure it was trying to run was wwv_flow.accept (which definitely existed). A second glance led me suspect that the problem might be in my dads.conf file (the Database Access Descriptor config file). I had a look at it; it looked fine to me. I went over it line by line and still couldn't see anything wrong with it.

Turns out I was looking to the wrong Jerry Bruckheimer vehicle; instead of Con Air I should have been looking to the subtlety of CSI. Here's what I was doing wrong (and if you're getting this same error when you try to upload a file in Apex you've probably made this same mistake); I had a typo in my dads.conf.

Instead of:

PlsqlAuthenticationMode Basic
SetHandler pls_handler
PlsqlDocumentTablename wwv_flow_file_objects$
PlsqlDatabaseUsername APEX_PUBLIC_USER
PlsqlDefaultPage apex
PlsqlDatabasePassword apex

I had:

PlsqlAuthenticationMode Basic
SetHandler pls_handler
PlsqlDocumentTablename wwv_flow_file_object$
PlsqlDatabaseUsername APEX_PUBLIC_USER
PlsqlDefaultPage apex
PlsqlDatabasePassword apex

Spotted it yet? I didn't either.

In typing my dads.conf I had typed 'object$' instead of 'objects$' in the line:

PlsqlDocumentTablename wwv_flow_file_objects$

Once I corrected this typo and restarted my web service it all worked. Easy-peasy - when you know how. So I've got to say thank you to this site which pointed me in the right direction.

Thursday, 2 October 2008

Google Motion Charts in Apex (or Me, February, March & Mummy)

I've got an old Iraqi 100 dinars note in my wallet (don't ask me why - long story) and it's got this huge picture of Saddam Hussein on it. Just how vain do you have to be as a president to put your own face on your country's money? Or what about President Saparmurat Niyazov of Turkmenistan who was so egocentric that he renamed the month of January after himself and April after his mother?

Crazy, huh? Except we've all got a little narcissistic dictator in us, which is why I sometimes obsessively keep an eye on this blog's hit-counter. Which is why I know that most people who chance upon this blog do so from googling "AnyCharts" or "FusionCharts" (see my post about integrating FusionCharts with Apex here). Flash charts are obviously a big thing: users find them informative and we developers find them fun to play with.

Which is why I nearly wet myself with excitement when I heard that Gapminder's really cool flash chart (go on, click the link and press play. We'll wait for you) had recently been rebranded as 'motion charts', released as a Google gadget and can be accessed using the Google visualization API (no, I hadn't heard of it either). How cool would it be to have one of them in your apex app? (The Google visualization gallery actually has quite a few interesting charts; they're probably worth a second look too.)

The Google motion chart page, fortunately, contains some sample code (although you might want to read the Google Visualization overview to fully understand how the whole thing holds together). To use it in your apex application all you have to do is create a Dynamic PL/SQL region and output the javascript code using htp.prn, populating the Google DataTable in a pl/sql loop.

And that's that. Easy-peasy when you know how.

The only small issues I've had with motion charts so far is that while they seem happy to display an annual timeline they do appear a little buggy when you try to portray smaller date increases, and no matter what the user guide says I am unable programmatically control the size or colour of the bubbles.