Why not [] as ActiveRecord::Base class method?

rubyonrails-talk
1

Here's a little method

  module ActiveRecord     class Base       def self.(id)         find(id)       end     end   end

So you can write

   MyModel[12]

as an equivalent to

   MyModle.find(12)

Just a little sugar, nothing else really. Is anyone aware of why that would be ill-advised? It seems to work with my extremely limited testing.

It's non-orthogonal with respect to association proxies, so maybe that's bad:

  MyModel[12] is the same as MyModel.find(12)

but

  MyModel.friends[12] is not the same as MyModel.friends.find(12)

2

jamis buck has suggested the same thing: http://weblog.jamisbuck.org/2007/4/4/activerecord-base-find-shortcut

3

My instinct is to say, "yes, but what happens when record #5 is deleted?" There are two problems at play: 1) The use of incrementing integers for primary keys (bad, btw, we need guids much of the time) misleads us into thinking of the table as an array indexed by the primary keys. It is not. It is a collection indexed by the primary keys. 2) The use of the operator with integer operands likewise intuitively directs to an array. But in ruby, a[5] might be the sixth element of an array, or the value of a hash for the key 5.

Since these classes are mapped to tables, and tables are certainly collections of rows, then the use of the operator is sensible.

HOWEVER...

You are not the sole maintainer of this code. Sooner or later, someone else is going to maintain it. You are changing a base behavior of the system. Be sure to leave markers.

Is MyModel.friends.find even well defined?