The raw content type string. Use when you need parameters such as charset or boundary which aren’t included in the content_type MIME type. Overridden by the X-POST_DATA_FORMAT header for backward compatibility.

Source Code

# File action_controller/request.rb, line 344
def content_type_with_parameters
  content_type_from_legacy_post_data_format_header ||
    env['CONTENT_TYPE'].to_s
end