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Showing posts from September, 2007

On Ruby on Rails with PostgreSQL, and Acts as Paranoid

Back a few years ago I was researching differences between PostgreSQL and MySQL databases, and chose PostgreSQL because at the time it supported foreign key constraints and many other fantastic SQL extensions that make developer's life a lot easier. Today I am sure MySQL is just as functional as PostgreSQL, and it does appear to be a more popular choice as the Rails DB than MySQL. I still prefer PostgreSQL, it just feels more natural to me coming out of Oracle background, so I am probably biased (who isn't?) Anyway, in the last year and a half or so, I've been writing Rails apps that use PG-based databases and found a few random tricks I'd love to share here. Opinions differ here, but just like accountants like the ancient double entry accounting system, I personally prefer a double validation system - where Rails validates my objects before/after updates, but the database double checks this using proper constraints. Rail's validation system is very robust and ext…

Ruby on Rails: Reducing clutter in actions by placing common code in filters

This is a tiny but useful tip, that saved many lines of repeated code in my controllers, hence why not share it :) Do Not Repeat Thyself?If you've looked at the controller code that's generated by scaffolding, you'll find something like this: def show @user = User.find(params[:id]) end def new @user = User.new end def destroy User.find(params[:id]).destroy end Sure, in this case all we are doing repeatedly is instantiating the user by a potentially available parameter value. What if instead we placed these common fetches in a controller filter, which would simply set an instance variable for us? Hell, we could even handle exceptions (such as invalid ID) in only one place this way! What not to like.When dealing with a more complicated route that has been defined, this instantiation may become quite a bit more elaborate, and the case for a filter is even more justified. Consider the case of building a collaboration system where you have projects…