You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: custom_attribute_mixin.rb
    path of file: ./repos/manageiq/app/models/mixins
    
    the code of the file until where you have to start completion: module CustomAttributeMixin
  extend ActiveSupport::Concern

  CUSTOM_ATTRIBUTES_PREFIX = "virtual_custom_attribute_".freeze
  SECTION_SEPARATOR        = ":SECTION:".freeze
  DEFAULT_SECTION_NAME     = 'Custom Attribute'.freeze

  CUSTOM_ATTRIBUTE_INVALID_NAME_WARNING = "A custom attribute name must begin with a letter (a-z, but also letters with diacritical marks and non-Latin letters) or an underscore (_). Subsequent characters can be letters, underscores, digits (0-9), or dollar sig
    
    def self.custom_attribute_arel(name_val, section)
      lambda do |t|
        ca_field    = CustomAttribute.arel_table

        field_where = ca_field[:resource_id].eq(t[:id])
        field_where = field_where.and(ca_field[:resource_type].eq(base_class.name))
        field_where = field_where.and(ca_field[:name].eq(name_val))
        field_where = field_where.and(ca_field[:section].eq(section)) if section

        # Because there is a `find_by` in the `define_method` above, we are
        # using a `take(1)` here as well, since a limit is assumed in each.
        # Without it, there can be some invalid queries if more than one result
        # is returned.
        t.grouping(ca_field.project(:value).where(field_where).take(1))
      end
    end