The Learning Journey

This is the trickiest part of Rails I came across so far:
In my has_many association I have a finder_sql that should reference the instance object id rather than the class object id.

has_many :breedtypes, :finder_sql => 'SELECT Breedtype.* FROM ... WHERE (cai = #{id})'

Now, who’d ever have thought that replacing the “double” quotes I had wrapping the “Select” statement, would change the context from which id is interpreted.

Single Quotes -> #{id} = Object ID
Double Quotes -> #{id} = Class ID

Here’s the quote that saved the day from Jeremy (on http://lists.rubyonrails.org/pipermail/rails/2005-February/002752.html)

When you use “double quotes” the string is interpolated immediately in Project class. When you use ’single quotes’ the string is interpolated by Rails in the context of a Project instance. Use single quotes & you’re good to go.

Phew!