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

Defining an association named '%{name}' is not allowed.

Error message

Defining an association named '%{name}' is not allowed.

What it means

Error "Defining an association named '%{name}' is not allowed." thrown in mongodb/mongoid.

Source

Thrown at lib/mongoid/association/relatable.rb:440

          end
        end

        if @options.key?(:fallback)
          unless @options[:fallback].respond_to?(:call)
            raise ArgumentError,
                  "The :fallback option for association '#{name}' on " \
                  "#{@owner_class} must be a Proc or lambda."
          end

          if @options.key?(:autobuild)
            raise ArgumentError,
                  "The :fallback option for association '#{name}' on " \
                  "#{@owner_class} cannot be combined with :autobuild."
          end
        end

        [ name, :"#{name}?", :"#{name}=" ].each do |n|
          raise Errors::InvalidRelation.new(@owner_class, n) if Mongoid.destructive_fields.include?(n)
        end
      end

      def polymorph!
        return unless polymorphic?

        @owner_class.polymorphic = true
      end

      def create_extension!(&block)
        return unless block

        extension_module_name = "#{@owner_class.to_s.demodulize}#{name.to_s.camelize}RelationExtension"
        silence_warnings do
          @owner_class.const_set(extension_module_name, Module.new(&block))
        end
        @extension = "#{@owner_class}::#{extension_module_name}".constantize
      end

View on GitHub (pinned to 0da0e23d71)

When it happens

Trigger: Thrown at lib/mongoid/association/relatable.rb:440 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/99dbe17196120eb9. Report an issue: GitHub.