Overwriting existing field #{name} in class #{klass.name}.

Error message

Overwriting existing field #{name} in class #{klass.name}.

What it means

Error "Overwriting existing field #{name} in class #{klass.name}." thrown in mongodb/mongoid.

Source

Thrown at lib/mongoid/fields/validators/macro.rb:88

        private

        # Determine if the field name is unique, if not raise an error.
        #
        # @example Check the field name.
        #   Macro.validate_name_uniqueness(Model, :name, {})
        #
        # @param [ Class ] klass The model class.
        # @param [ Symbol ] name The field name.
        # @param [ Hash ] options The provided options.
        #
        # @raise [ Errors::InvalidField ] If the name is not allowed.
        #
        # @api private
        def validate_name_uniqueness(klass, name, options)
          return unless !options[:overwrite] && klass.fields.keys.include?(name.to_s)
          raise Errors::InvalidField.new(klass, name, name) if Mongoid.duplicate_fields_exception

          Mongoid.logger.warn("Overwriting existing field #{name} in class #{klass.name}.") if Mongoid.logger
        end

        # Validate that the field options are allowed.
        #
        # @api private
        #
        # @example Validate the field options.
        #   Macro.validate_options(Model, :name, { localized: true })
        #
        # @param [ Class ] klass The model class.
        # @param [ Symbol ] name The field name.
        # @param [ Hash ] options The provided options.
        #
        # @raise [ Errors::InvalidFieldOption ] If an option is invalid.
        def validate_options(klass, name, options)
          options.keys.each do |option|
            if !OPTIONS.include?(option) && !Fields.options.include?(option)
              raise Errors::InvalidFieldOption.new(klass, name, option, OPTIONS)

View on GitHub (pinned to 0da0e23d71)

When it happens

Trigger: Thrown at lib/mongoid/fields/validators/macro.rb:88 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/a459c731d9bc794e. Report an issue: GitHub.