在运行时查找ActiveRecord类的关联？

class User< ActiveRecord::Base
  has_many :posts
  has_one :profile
end

class Post< ActiveRecord::Base
  belongs_to :user
end

class Profile< ActiveRecord::Base
  belongs_to :user
end

user = User.first

# 获取User类的关联
associations = User.reflect_on_all_associations

# 输出关联名称和类型
associations.each do |association|
  puts "关联名称：#{association.name}, 关联类型：#{association.macro}"
end

# 输出关联类型为has_many的关联名称
has_many_associations = User.reflect_on_all_associations(:has_many)
has_many_associations.each do |association|
  puts "has_many关联名称：#{association.name}"
end

# 输出关联类型为has_one的关联名称
has_one_associations = User.reflect_on_all_associations(:has_one)
has_one_associations.each do |association|
  puts "has_one关联名称：#{association.name}"
end

关联名称：posts, 关联类型：has_many
关联名称：profile, 关联类型：has_one
has_many关联名称：posts
has_one关联名称：profile