从Ruby模型中获取属于某个类的字段

class User < ActiveRecord::Base
  # 模型定义
end

user = User.new
user.attributes # 返回包含所有属性和对应值的哈希表

# 获取属于User类的字段
user.attributes.select { |key, _| User.column_names.include?(key) }

class User < ActiveRecord::Base
  # 模型定义
end

user = User.new
User.column_names.select { |column| user.respond_to?(column) }

class User < ActiveRecord::Base
  has_many :posts
  belongs_to :group
end

User.reflect_on_all_associations.select { |assoc| assoc.class_name == 'Post' }