mongodb/mongoid · error · Mongoid::Errors::InvalidDotDollarAssignment

Cannot set the %{attr} attribute on the %{klass} class.

Error message

Cannot set the %{attr} attribute on the %{klass} class.

What it means

Error "Cannot set the %{attr} attribute on the %{klass} class." thrown in mongodb/mongoid.

Source

Thrown at lib/mongoid/fields.rb:276

    #
    # @return [ true | false ] If this field is dotted or dollared.
    def dot_dollar_field?(name)
      n = aliased_fields[name] || name
      fields.key?(n) && (n.include?('.') || n.start_with?('$'))
    end

    # Validate whether or not the field starts with a dollar sign ($) or
    # contains a dot/period (.).
    #
    # @api private
    #
    # @raise [ InvalidDotDollarAssignment ] If contains dots or starts with a dollar.
    #
    # @param [ String ] name The field name.
    def validate_writable_field_name!(name)
      return unless dot_dollar_field?(name)

      raise Errors::InvalidDotDollarAssignment.new(self.class, name)
    end

    class << self
      # Stores the provided block to be run when the option name specified is
      # defined on a field.
      #
      # No assumptions are made about what functionality the handler might
      # perform, so it will always be called if the `option_name` key is
      # provided in the field definition -- even if it is false or nil.
      #
      # @example
      #   Mongoid::Fields.option :required do |model, field, value|
      #     model.validates_presence_of field if value
      #   end
      #
      # @param [ Symbol ] option_name the option name to match against
      # @param &block the handler to execute when the option is provided.
      def option(option_name, &block)

View on GitHub (pinned to 0da0e23d71)

When it happens

Trigger: Thrown at lib/mongoid/fields.rb:276 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of mongodb/mongoid@0da0e23d71 (2026-08-23). Data as JSON: /api/errors/73d07a68aa05aa2c. Report an issue: GitHub.