问返回不一致值的记忆化类变量

EN

class AirtableModel
  def initialize(hash)
    hash.each do |attribute_name, attribute_value|
      attribute_value = self.class.first_value_from_arrays_with_singular_key_name(attribute_name, attribute_value)
      # ^^^ Airtable always returns references as Arrays. If the relationship is a belongs_to, we pull out the value from the Array.

      begin
        attribute_name_as_class = attribute_name.to_s.singularize.camelize.constantize
        # ^^^ Converts the attribute's name to a class constant. Used to make the generated method retrieve class records instead of ids. If the class doesn't exist, its NameError is caught below.
        instance_variable_set("@#{attribute_name}_airtable_ids", attribute_value)

        self.class.send(:define_method, attribute_name.to_sym) do
          result = attribute_name_as_class.find_all_by_airtable_id(instance_variable_get("@#{attribute_name}_airtable_ids"))
          result.length <= 1 ? result.first : result
        end
      rescue NameError
        # Triggered if `attribute_name_as_class` doesn't match an existing class
        instance_variable_set("@#{attribute_name}", attribute_value)
        self.class.send(:define_method, attribute_name.to_sym) do
          instance_variable_get("@#{attribute_name}")
        end
      end
    end
  end

  # Reaches out to Airtable to get all records for this class's table (the Airtable table matches the class name). Collects the resulting data into an array of Hashes.
  # One such hash might look like this:
  #   {
  #     'id' => <unique string ID assigned by Airtable>,
  #     'fields' => {
  #       'db_id' => <Unique integer ID. I added this to emulate a database record>,
  #       ...
  #     }
  #   }
  def self.airtable
    @airtable_records ||= AirtableService.records_from_table(table_name: "#{self}s").each.map do |raw|
      object_properties = raw['fields']
      object_properties['airtable_id'] = raw['id']
      object_properties['id'] = object_properties['db_id']

      Hash[object_properties.collect { |k, v| [k.snakecase.parameterize.underscore.to_sym, v] }]
      # ^^^ Converts parameter name to snake-case symbol, i.e. :db_id
    end
  end

  def self.all
    @all_records ||= airtable.map { |b| new(b) }
  end

  def self.find_by_airtable_id(airtable_id)
    objects = all.select { |b| b.airtable_id == airtable_id }
    raise "non unique airtable_id found" if objects.size > 1
    objects.first
  end

  def self.find_all_by_airtable_id(airtable_ids)
    [airtable_ids].flatten.map { |aid| find_by_airtable_id(aid) }
    # ^^^ Accomodates airtable_ids as an Array or a single value
  end

  def self.first
    all.first
  end

  def self.last
    all.last
  end
end

[Table Foo]                   [Table FooBar]                  [Table Bar]
fooBars <==========---------> foo     bar <---------========> fooBars

class Foo < AirtableModel
end

class FooBar < AirtableModel
end

class Bar < AirtableModel
end