Many thanks to Hanzík for the Czech translations!

tcc-case-title
extremely geeky  extremely geeky

Case 108

Sweet Tooth

The monk Djishin was tasked with creating a web page for querying the system’s inventory table of rice bags. Glumly contemplating the dull day’s work that lay before him, the monk had a sudden inspiration:

I must produce a presentation-layer object to hold the parameters from the search form, he thought, as well as a service-layer object to represent each row returned by the search. Yet these both would have the same attributes as the RiceBag object we currently use for creating new table rows. Can I not simply reuse that database-layer object for these other two purposes?

With growing excitement, he thought: If a database object were suitably annotated, I could develop a framework which would acquire the form input, validate it, convert it to SQL, query the table, and present the search results to the user in tabular format... all requiring the most minimal effort on the part of the framework’s consumer!

The monk thus spent the next few days happily coding the framework, with the RiceBag search page as its proof-of-concept.

- - -

At the end of the week Djishin proudly showed the fruits of his labor to master Banzen. The master studied the new framework, nodded, and ordered Djishin to convert seven existing search pages in the application to use it, starting with the Warrior page.

After the monk ran off to comply, a nun who had been standing nearby approached Banzen.

“Master,” asked the nun, “The Warrior object has but a single Status value. If the user’s query is represented by a single Warrior, how could we ask for Warriors whose Status is either Missing, Retired, or Dead?”

“We could not,” said Banzen.

“Furthermore,” continued the nun, “The Warrior object contains only information stored in the Warrior table. How could we find Warriors by the types of Weapons they use, or by the Regiments they have served in, since these require joining to child tables?”

“We could not,” said Banzen.

The master took a small dark nugget from the jar he kept on his desk, giving it to the puzzled nun. “There once was a monk who tired of rice. One day he stumbled upon the art of making kuro sato—black sugar candy. For years he nibbled piece after piece throughout the day, gradually becoming flabby and pale and void of tooth. What was his master’s error?”

“Failing to forbid the candy,” said the nun.

Banzen shook his head and pushed the heavy jar across the desk.

“Finish that by tomorrow evening,” commanded Banzen. “Then you will understand Djishin’s correction.”