Relationships of model

How can I get all relationships for model. IE, I've got User model:

class User < AR开发者_StackOverflow中文版::Base
  has_many :messages, :foreign_key => 'author'
  has_many :posts
  belongs_to :role
end

So how can I know which relationships User model has got? And foreign_keys if they are presented.

User.reflect_on_all_associations.each do |assoc|
  puts "#{assoc.macro} #{assoc.name}"
end

Outputs:

has_many messages
has_many posts
belongs_to role

The reflect_on_all_associations method return an array of MacroReflection objects. They support other methods as well, for querying the options hash of each association and other useful stuff.