Question about accepts_nested_attributes_for and reject_if


I am developing a rails 3.0.3 application and
accepts_nested_attributes_for method is giving me pains.

To simplify the issue, I created a new app and generated 2 models.


The docs seem to contradict each other. First...

    # You may also set a :reject_if proc to silently ignore any new record
    # hashes if they fail to pass your criteria. For example, the previous
    # example could be rewritten as:

But then....

      # Allows you to specify a Proc or a Symbol pointing to a method
      # that checks whether a record should be built for a certain attribute
      # hash. The hash is passed to the supplied Proc or the method
      # and it should return either +true+ or +false+. When no :reject_if
      # is specified, a record will be built for all attribute hashes that
      # do not have a <tt>_destroy</tt> value that evaluates to true.
      # Passing <tt>:all_blank</tt> instead of a Proc will create a proc
      # that will reject a record where all the attributes are blank.

The code says the second is true... from active_record/nested_attributes.rb around line 376...

It loops through all the nested attributes...
  - if the 'id' is blank and we don't reject the record, then build it.
  - else we have an 'id' so find the record and if we don't reject it, add it to the target and *then* mark it for destruction.

Unless I'm reading it wrong :slight_smile:

      attributes_collection.each do |attributes|
        attributes = attributes.with_indifferent_access

        if attributes['id'].blank?
          unless reject_new_record?(association_name, attributes)
        elsif existing_record = existing_records.detect { |record| == attributes['id'].to_s }
          association.send(:add_record_to_target_with_callbacks, existing_record) if !association.loaded? && !call_reject_if(association_name, attributes)
          assign_to_or_mark_for_destruction(existing_record, attributes, options[:allow_destroy])
          raise_nested_attributes_record_not_found(association_name, attributes['id'])