Any framework that has convention over configuration has the the problem that newcomers have to learn the conventions.
I think that one of the biggest stumbling blocks to new users of Rails is the way associations are described. Just look at the number of questions on this on SO. M-1 and 1-M and even M-1-M are really quite simple concepts, but the Rails naming of these relationships just serves to confuse.
Here is a good definition that kind of gets at the root cause:
belongs_to and has_many do not describe either the ownership or the scope or the life cycles for the objects they relate. They may give that impression because ‘belongs’ implies ownership and responsibility, but they merely describe the references (the keys) between the objects.
Even the documentation states:
Associations are a set of macro-like class methods for tying objects together through foreign keys
In that case isn’t it easier if we called a spade a spade, and not a shovel?
Surely all the confusion would be cleared up by renaming
belongs_to? This would lower the barrier to learning Rails, resulting in less mistakes, less time wasted asking and answering on SO, less discussions, less blogs -> overall a HUGE time saver for the community over the long term (against which you have to weigh the short-term pain of adopting the change of course).
Example 1 - one-to-one
class Employee has_one :salary end class Salary has_key_for :employee end
Example 2 - one-to-many
class Manager has_many :employees end class Employee < ActiveRecord::Base has_key_for :manager end
Example 3- M-1-M
class Project has_many :assignments has_many :employees, through: :assignments end class Employee has_many :assignments has_many :projects, through: :assignments end class Assignment has_key_for :employee has_key_for :project end
Example 4 - Polymorphic
class Address has_key_for :addressable, :polymorphic => true end class Person has_one :address, as: :addressable end
I think this just leaves “has_and_belongs_to_many” which personally I have always hated. Why not just use “has_many”? Since when you have an explicit join table for M-M, you use “through”…so if there is no “through” specified, we know it is a HABTM.