Auto-Generate Foreign-Key Constraints in Rails

I literally just lobbed into my hotel room in Oslo after 30+ hours in transit. (I left home @ 12:30pm on Monday 15th and arrived here @ 21:30 on Tuesday 16th Melbourne time.) It’s my first time in Scandinavia and so far I’m loving it. The people are friendly (and ahem rather attractive I must say) and I’m hanging out to try some scandinavian beer!

So anyways, after resisting the temptation to turn on my laptop, I finally caved and whipped up a little bit of code to auto-generate foreign-key relationships for migration scripts:

module ActiveRecord
  module ConnectionAdapters
    class ColumnDefinition
      alias nofk_to_sql :to_sql

      def to_sql
        name.to_s =~ /(.*)_id$/ ? "#{nofk_to_sql} REFERENCES #{Migrator.proper_table_name($1)} (id)" : nofk_to_sql
      end
      alias to_s :to_sql
    end
  end
end

The code assumes that if you have a column named customer_id in say an order_s_ table, then you want a foreign key to the id column in the customer_s_ table. That doesn’t handle situations where you have multiple foreign keys to the same table but…meh…I don’t have models that sophisticated yet so bite me :)

Just looking back on it now, it was so trivial to implement that there is more syntactic noise than actual code. Hmmmm.

UPDATE: The plugin is now available in downloadable form and supports a :references option for multiple columns or columns that aren’t named for the table they reference.