ODTUG Kaleidoscope 2008 : Day 3

ODTUG Kaleidoscope 2008 : Day 3 - Experts Day

Building Advanced Tabular Forms was the first subject of the day. In APEX you can build tabular forms (a multi record update form) using a wizard or manually (with the APEX_ITEM API and processing with the APEX_APPLICATION API. Another option is using a collection which gives you full control on the processing - like distributing your data over multiple tables.

After that one Dimitri Gielis presented on Creating Advanced Charts with APEX. He showed the audience what you can do using the charting options of APEX. Impressive!

Next was the Oracle APEX Developer of the Year 2007, Patrick Wolf. His main message is that you can speed up your development process (even further!) when you use the right third party tools. The tools you can't do without as an APEX developer are - apart from Firefox itself:

Firebug - a great extension on Firefox
Web Developer - another Firefox extension
YSlow - a performance monitor, again an Firefox extension
Live HTTP Header - to track traffic between the browser and from server, again Firefox
APEX Developer Plugin - An extension on APEX that Patrick built, to make your live (even) more easy
APEX Essentials - An APEX application to check the quality of your APEX application, free, adaptable and extendible, created by Patrick
jquery - A great Javascript pack, this may be included in the next version of APEX
APEXLib Framework - A framework, by Patrick, that reduces the writing of code even more

I will report on the presentations of Anton Nielsen and Carl Backstrom later (because I'm at the airport right now and have to get into the plane soon).

Comments

Filtering in the APEX Interactive Grid

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apex_application.g_f0x array processing in Oracle 12

If you created your own "updatable reports" or your custom version of tabular forms in Oracle Application Express, you'll end up with a query that looks similar to this one: then you disable the " Escape special characters " property and the result is an updatable multirecord form. That was easy, right? But now we need to process the changes in the Ename column when the form is submitted, but only if the checkbox is checked. All the columns are submitted as separated arrays, named apex_application.g_f0x - where the "x" is the value of the "p_idx" parameter you specified in the apex_item calls. So we have apex_application.g_f01, g_f02 and g_f03. But then you discover APEX has the oddity that the "checkbox" array only contains values for the checked rows. Thus if you just check "Jones", the length of g_f02 is 1 and it contains only the empno of Jones - while the other two arrays will contain all (14) rows. So for

Stop using validations for checking constraints !

If you run your APEX application - like a Form based on the EMP table - and test if you can change the value of Department to something else then the standard values of 10, 20, 30 or 40, you'll get a nice error message like this: But it isn't really nice, is it? So what do a lot of developers do? They create a validation (just) in order to show a nicer, better worded, error message like "This is not a valid department". And what you then just did is writing code twice : Once in the database as a (foreign key) check constraint and once as a sql statement in your validation. And we all know : writing code twice is usually not a good idea - and executing the same query twice is not enhancing your performance! So how can we transform that ugly error message into something nice? By combining two APEX features: the Error Handling Function and the Text Messages! Start with copying the example of an Error Handling Function from the APEX documentation. Create this function

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