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

Accepting nested attributes for %{association} is limited to

Error message

Accepting nested attributes for %{association} is limited to %{limit} documents.

What it means

Error "Accepting nested attributes for %{association} is limited to %{limit} documents." thrown in mongodb/mongoid.

Source

Thrown at lib/mongoid/association/nested/many.rb:30

        # passed to the macro.
        #
        # This attempts to perform 3 operations, either one of an update of
        # the existing association, a replacement of the association with a new
        # document, or a removal of the association.
        #
        # It raises an argument error if the attributes are not a Hash or an
        # Array of key/value pairs.
        #
        # @example Build the nested attrs.
        #   many.build(person)
        #
        # @param [ Document ] parent The parent document of the association.
        # @param [ Hash ] options The options.
        #
        # @return [ Array ] The attributes.
        def build(parent, options = {})
          @existing = parent.send(association.name)
          raise Errors::TooManyNestedAttributeRecords.new(existing, options[:limit]) if over_limit?(attributes)

          attributes.each do |attrs|
            if attrs.is_a?(::Hash)
              process_attributes(parent, attrs.with_indifferent_access)
            elsif attrs.is_a?(Array) && attrs.length > 1 && attrs[1].respond_to?(:with_indifferent_access)
              process_attributes(parent, attrs[1].with_indifferent_access)
            elsif attrs.is_a?(Array) && attrs.length.even?
              process_attributes(parent, Hash[*attrs].with_indifferent_access)
            else
              raise ArgumentError,
                    "Attributes for nested association '#{association.name}' must be a Hash or an Array of key/value pairs."
            end
          end
        end

        # Create the new builder for nested attributes on one-to-many
        # associations.
        #

View on GitHub (pinned to 0da0e23d71)

When it happens

Trigger: Thrown at lib/mongoid/association/nested/many.rb:30 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/103869e5d85d299f. Report an issue: GitHub.