Amateur rails programmer struggling to use the fields_for form builder. My rails application (on

Question

0

Asked: May 21, 20262026-05-21T15:44:20+00:00 2026-05-21T15:44:20+00:00

Amateur rails programmer struggling to use the fields_for form builder. My rails application (on

0

Amateur rails programmer struggling to use the fields_for form builder. My rails application (on v=2.3.11) tracks laboratory protocols and the animals used on those protocols (their weights, etc).

My specific problem is that protocols can only have a certain number of animals, but that number allowed is specific to a species.

The nested form behavior should display a listing of all the species of animals and an edit box for the number allowed on the protocol.

Models: Protocol, Allowed_Animal, Species

Species Model

class Species < ActiveRecord::Base
  has_many :animals, :order => "band"
  has_many :allowed_animals
end

Protocol Model

class Protocol < ActiveRecord::Base
  has_and_belongs_to_many :animals, :order => "band"
  has_many :allowed_animals
  accepts_nested_attributes_for :allowed_animals
end

Allowed_Animal Model

class AllowedAnimal < ActiveRecord::Base
  belongs_to :protocol
  has_one :species
end

The table for allowed_animal includes:

id, protocol_id, species_id, number, created_at, updated_at

The nested form works like this:

<% form_for(@protocol) do |f| %>
  <%= f.error_messages %>

  <p>
    <%= f.label :title %><br />
    <%= f.text_field :title %>
  </p>
  <p>
    <%= f.label :number %><br />
    <%= f.text_field :number %>
  </p>

  <p>
    Number of animals allowed on protocol:
  </p>
  <div class="left_indent">
    <table>
      <% f.fields_for :allowed_animals, Species.all do |a| %>
      <tr>
        <td><i><%= a.object[:name] %></i></td>
        <td><%= a.text_field :number, :value => @protocol.allowed_animals(a), :size=>2 %></td>
        <%= a.text_field :species_id, :value => a.object[:id], :hidden => true %>
      </tr>
      <% end %>
    </table>
  </div>

  <p>
    Users on protocol:
  </p>
  <div class="left_indent">
    <%= render :partial => 'protocols/users_on_protocol_form', :locals =>{:protocol => @protocol, :users => User.current} %>
  </div>

  <p>
    <%= f.submit 'Save' %>
  </p>
<% end %>

The form displays how I would like it to, but after submission, I get the error:

wrong number of arguments (0 for 1)

in the controller as it tries to do:

@protocol = Protocol.new(params[:protocol])

I am not sure where to go from here. Do I need to have a build method in my model? Or do I need to do anything special in my controller? Is there something wrong with my form_builder code and how it iterates through the species?

Any ideas?

Application trace:

/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/nested_attributes.rb:343:in `allowed_animals'
/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/nested_attributes.rb:343:in `send'
/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/nested_attributes.rb:343:in `assign_nested_attributes_for_collection_association'
/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/nested_attributes.rb:244:in `allowed_animals_attributes='
/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/base.rb:2918:in `send'
/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/base.rb:2918:in `assign_attributes'
/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/base.rb:2914:in `each'
/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/base.rb:2914:in `assign_attributes'
/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/base.rb:2787:in `attributes='
/var/lib/gems/1.8/gems/activerecord-2.3.11/lib/active_record/base.rb:2477:in `initialize'
/media/Data/Animal-Record-Keeping/app/controllers/protocols_controller.rb:42:in `new'
/media/Data/Animal-Record-Keeping/app/controllers/protocols_controller.rb:42:in `create'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/base.rb:1333:in `send'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/base.rb:1333:in `perform_action_without_filters'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/filters.rb:617:in `call_filters'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/filters.rb:610:in `perform_action_without_benchmark'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
/var/lib/gems/1.8/gems/activesupport-2.3.11/lib/active_support/core_ext/benchmark.rb:17:in `ms'
/var/lib/gems/1.8/gems/activesupport-2.3.11/lib/active_support/core_ext/benchmark.rb:17:in `ms'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/rescue.rb:160:in `perform_action_without_flash'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/flash.rb:151:in `perform_action'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/base.rb:532:in `send'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/base.rb:532:in `process_without_filters'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/filters.rb:606:in `process'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/base.rb:391:in `process'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/base.rb:386:in `call'
/var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/routing/route_set.rb:438:in `call'

Parameters:

{"commit"=>"Save",
 "protocol"=>{"number"=>"Test number",
 "start_date(1i)"=>"2011",
 "start_date(2i)"=>"4",
 "title"=>"Test title",
 "start_date(3i)"=>"12",
 "flight_exempt"=>"0",
 "allowed_animals_attributes"=>{"0"=>{"number"=>"7",
 "id"=>"2",
 "species_id"=>"2"},
 "1"=>{"number"=>"11",
 "id"=>"3",
 "species_id"=>"3"},
 "2"=>{"number"=>"13",
 "id"=>"4",
 "species_id"=>"4"},
 "3"=>{"number"=>"17",
 "id"=>"5",
 "species_id"=>"5"}},
 "summary"=>"Test summary"},
 "user_id"=>{"33"=>"0",
 "6"=>"0",
 "14"=>"0",
 "9"=>"0",
 "37"=>"0",
 "38"=>"0",
 "1"=>"1",
 "39"=>"0",
 "40"=>"0",
 "18"=>"0",
 "31"=>"0",
 "21"=>"0",
 "32"=>"0",
 "5"=>"0"}}

Development Log

# Logfile created on Tue Apr 12 18:11:11 -0400 2011DEPRECATION WARNING: Giving :session_key to SessionStore is deprecated, please use :key instead. (called from new at /var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/middleware_stack.rb:72)
  [4;36;1mSQL (0.1ms)[0m   [0;1mSET SQL_AUTO_IS_NULL=0[0m


Processing MainController#index (for 127.0.0.1 at 2011-04-12 18:11:12) [GET]
::: Checking session expiry
::: Session has not expired. Reinitialising.
::: Initializing session expiry. Expires at Tue Apr 12 18:26:12 -0400 2011
  [4;35;1mUser Load (0.1ms)[0m   [0mSELECT * FROM `users` WHERE (end_date is null) ORDER BY name[0m
  [4;36;1mUser Load (0.1ms)[0m   [0;1mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Weekend') ORDER BY name[0m
  [4;35;1mUser Load (0.1ms)[0m   [0mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Medic') ORDER BY name[0m
  [4;36;1mUser Load (0.2ms)[0m   [0;1mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Anim') ORDER BY name[0m
Rendering template within layouts/main
Rendering main/index
Rendered layouts/_standard_head (3.2ms)
  [4;35;1mUser Columns (0.5ms)[0m   [0mSHOW FIELDS FROM `users`[0m
  [4;36;1mUser Load (0.1ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;36;1manimal Load (0.1ms)[0m   [0;1mSELECT `animals`.* FROM `animals` INNER JOIN `cages` ON `animals`.cage_id = `cages`.id WHERE ((`cages`.user_id = 1)) ORDER BY band[0m
  [4;35;1manimal Columns (0.5ms)[0m   [0mSHOW FIELDS FROM `animals`[0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT `animals`.* FROM `animals` INNER JOIN `cages` ON `animals`.cage_id = `cages`.id WHERE ((`cages`.user_id = 1)) ORDER BY band[0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCage Load (0.1ms)[0m   [0mSELECT * FROM `cages` WHERE (date_destroyed is null) AND (`cages`.user_id = 1) ORDER BY name[0m
  [4;36;1mCage Columns (0.4ms)[0m   [0;1mSHOW FIELDS FROM `cages`[0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `cages` WHERE (date_destroyed is null) AND (`cages`.user_id = 1) ORDER BY name[0m
Rendered layouts/_menubar (87.9ms)
Rendered layouts/_menubar_login (103.2ms)
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;36;1mprotocols_users Columns (0.5ms)[0m   [0;1mSHOW FIELDS FROM `protocols_users`[0m
  [4;35;1mProtocol Load (0.1ms)[0m   [0mSELECT * FROM `protocols` INNER JOIN `protocols_users` ON `protocols`.id = `protocols_users`.protocol_id WHERE (`protocols_users`.user_id = 1 ) ORDER BY number[0m
  [4;36;1mProtocol Columns (0.4ms)[0m   [0;1mSHOW FIELDS FROM `protocols`[0m
  [4;35;1mTraining Load (0.1ms)[0m   [0mSELECT * FROM `trainings` WHERE (`trainings`.user_id = 1) [0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (end_date is null) ORDER BY name[0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (end_date is null) ORDER BY name[0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Anim') ORDER BY name[0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Anim') ORDER BY name[0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Medic') ORDER BY name[0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Medic') ORDER BY name[0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Weekend') ORDER BY name[0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Weekend') ORDER BY name[0m
  [4;36;1mUser Load (0.1ms)[0m   [0;1mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Admin') ORDER BY name[0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (end_date is null and job_type regexp 'Admin') ORDER BY name[0m
Rendered main/_sidebar (31.1ms)
Completed in 240ms (View: 197, DB: 3) | 200 OK [http://localhost/]
DEPRECATION WARNING: Giving :session_key to SessionStore is deprecated, please use :key instead. (called from new at /var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/middleware_stack.rb:72)
  [4;36;1mSQL (0.2ms)[0m   [0;1mSET SQL_AUTO_IS_NULL=0[0m


Processing ProtocolsController#new (for 127.0.0.1 at 2011-04-12 18:11:14) [GET]
::: Checking session expiry
::: Session has not expired. Reinitialising.
::: Initializing session expiry. Expires at Tue Apr 12 18:26:14 -0400 2011
  [4;35;1mProtocol Columns (0.5ms)[0m   [0mSHOW FIELDS FROM `protocols`[0m
Rendering template within layouts/standard
Rendering protocols/new
  [4;36;1mSpecies Load (0.1ms)[0m   [0;1mSELECT * FROM `species` [0m
  [4;35;1mSpecies Columns (0.4ms)[0m   [0mSHOW FIELDS FROM `species`[0m
  [4;36;1mAllowedanimal Load (0.3ms)[0m   [0;1mSELECT * FROM `allowed_animals` WHERE (protocol_id = NULL and species_id = 70099589946800) LIMIT 1[0m
  [4;35;1mAllowedanimal Load (0.1ms)[0m   [0mSELECT * FROM `allowed_animals` WHERE (protocol_id = NULL and species_id = 70099593009960) LIMIT 1[0m
  [4;36;1mAllowedanimal Load (0.1ms)[0m   [0;1mSELECT * FROM `allowed_animals` WHERE (protocol_id = NULL and species_id = 70099592966760) LIMIT 1[0m
  [4;35;1mAllowedanimal Load (0.1ms)[0m   [0mSELECT * FROM `allowed_animals` WHERE (protocol_id = NULL and species_id = 70099592896700) LIMIT 1[0m
  [4;36;1mUser Load (0.1ms)[0m   [0;1mSELECT * FROM `users` WHERE (end_date is null) ORDER BY name[0m
  [4;35;1mUser Columns (0.5ms)[0m   [0mSHOW FIELDS FROM `users`[0m
  [4;36;1mUser Load (0.1ms)[0m   [0;1mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 33) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;35;1mUser Load (0.1ms)[0m   [0mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 38) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;36;1mUser Load (0.0ms)[0m   [0;1mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 21) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;35;1mUser Load (0.1ms)[0m   [0mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 1) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;36;1mUser Load (0.0ms)[0m   [0;1mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 14) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;35;1mUser Load (0.0ms)[0m   [0mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 37) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;36;1mUser Load (0.0ms)[0m   [0;1mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 31) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;35;1mUser Load (0.0ms)[0m   [0mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 39) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;36;1mUser Load (0.1ms)[0m   [0;1mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 5) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;35;1mUser Load (0.0ms)[0m   [0mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 18) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;36;1mUser Load (0.0ms)[0m   [0;1mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 32) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;35;1mUser Load (0.0ms)[0m   [0mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 9) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;36;1mUser Load (0.0ms)[0m   [0;1mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 40) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
  [4;35;1mUser Load (0.0ms)[0m   [0mSELECT `users`.id FROM `users` INNER JOIN `protocols_users` ON `users`.id = `protocols_users`.user_id WHERE (`users`.`id` = 6) AND (`protocols_users`.protocol_id = NULL ) ORDER BY name LIMIT 1[0m
Rendered protocols/_users_on_protocol_form (19.7ms)
Rendered protocols/_form (123.0ms)
Rendered layouts/_standard_head (2.4ms)
  [4;36;1mUser Load (0.1ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;36;1manimal Load (0.1ms)[0m   [0;1mSELECT `animals`.* FROM `animals` INNER JOIN `cages` ON `animals`.cage_id = `cages`.id WHERE ((`cages`.user_id = 1)) ORDER BY band[0m
  [4;35;1manimal Columns (0.6ms)[0m   [0mSHOW FIELDS FROM `animals`[0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT `animals`.* FROM `animals` INNER JOIN `cages` ON `animals`.cage_id = `cages`.id WHERE ((`cages`.user_id = 1)) ORDER BY band[0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;35;1mCage Load (0.1ms)[0m   [0mSELECT * FROM `cages` WHERE (date_destroyed is null) AND (`cages`.user_id = 1) ORDER BY name[0m
  [4;36;1mCage Columns (0.4ms)[0m   [0;1mSHOW FIELDS FROM `cages`[0m
  [4;35;1mCACHE (0.0ms)[0m   [0mSELECT * FROM `users` WHERE (`users`.`id` = 1) [0m
  [4;36;1mCACHE (0.0ms)[0m   [0;1mSELECT * FROM `cages` WHERE (date_destroyed is null) AND (`cages`.user_id = 1) ORDER BY name[0m
Rendered layouts/_menubar (122.0ms)
Rendered layouts/_menubar_login (124.0ms)
Rendered layouts/_standard_layout (127.8ms)
Completed in 280ms (View: 266, DB: 4) | 200 OK [http://localhost/protocols/new]
DEPRECATION WARNING: Giving :session_key to SessionStore is deprecated, please use :key instead. (called from new at /var/lib/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/middleware_stack.rb:72)
  [4;35;1mSQL (0.1ms)[0m   [0mSET SQL_AUTO_IS_NULL=0[0m


Processing ProtocolsController#create (for 127.0.0.1 at 2011-04-12 18:11:43) [POST]
  Parameters: {"commit"=>"Save", "protocol"=>{"start_date(1i)"=>"2011", "number"=>"Test Number", "start_date(2i)"=>"4", "start_date(3i)"=>"12", "title"=>"Test Title", "allowed_animals_attributes"=>{"0"=>{"number"=>"7", "id"=>"2", "species_id"=>"2"}, "1"=>{"number"=>"11", "id"=>"3", "species_id"=>"3"}, "2"=>{"number"=>"13", "id"=>"4", "species_id"=>"4"}, "3"=>{"number"=>"17", "id"=>"5", "species_id"=>"5"}}, "flight_exempt"=>"0", "summary"=>"Test Summary"}, "user_id"=>{"6"=>"0", "33"=>"0", "9"=>"0", "14"=>"0", "37"=>"0", "38"=>"0", "40"=>"0", "39"=>"0", "1"=>"1", "18"=>"0", "31"=>"0", "32"=>"0", "21"=>"0", "5"=>"0"}}
::: Checking session expiry
::: Session has not expired. Reinitialising.
::: Initializing session expiry. Expires at Tue Apr 12 18:26:43 -0400 2011
  [4;36;1mProtocol Columns (0.6ms)[0m   [0;1mSHOW FIELDS FROM `protocols`[0m

ArgumentError (wrong number of arguments (0 for 1)):
  app/controllers/protocols_controller.rb:42:in `new'
  app/controllers/protocols_controller.rb:42:in `create'
  /var/lib/gems/1.8/gems/ruby-debug-ide-0.4.9/lib/ruby-debug-ide.rb:109:in `debug_load'
  /var/lib/gems/1.8/gems/ruby-debug-ide-0.4.9/lib/ruby-debug-ide.rb:109:in `debug_program'
  /var/lib/gems/1.8/gems/ruby-debug-ide-0.4.9/bin/rdebug-ide:87
  /var/lib/gems/1.8/bin/rdebug-ide:19:in `load'
  /var/lib/gems/1.8/bin/rdebug-ide:19

Rendered rescues/_trace (46.0ms)
Rendered rescues/_request_and_response (1.7ms)
Rendering rescues/layout (internal_server_error)

Report

Leave an answer
Cancel reply

You must login to add an answer.

Need An Account,

1 Answer

Editorial Team · Answer 1 · 2026-05-21T15:44:21+00:00

I figured out that the problem was that I had a function in my Protocol model with the same name as the model I was trying to nest (AllowedAnimal). When calling protocol.allowed_animals it was calling the function (with not enough arguments) instead of returning the nested fields_for.

I also had to change the relationship to belongs_to in my Allowed Animal Model to get my allowed_animal.species to work:

class AllowedAnimal < ActiveRecord::Base
  belongs_to :protocol
  belongs_to :species
end

And add a method in my model to build out the allowed_animals for a new protocol:

def build_allowed_animals
  abs = Array.new
  for sp in Species.all
    ab = AllowedAnimal.new
    ab.species = sp
    ab.number = 0
    abs << ab
  end
  self.allowed_animals = abs
end

Call the method in my Protocol Controller:

def new
  @protocol = Protocol.new
  @protocol.build_allowed_bats
  respond_to do |format|
    format.html # new.html.erb
    format.xml  { render :xml => @protocol }
  end
end

And make a few edits to my form:

<% form_for(@protocol) do |f| %>
  <%= f.error_messages %>

  <p>
    <%= f.label :title %><br />
    <%= f.text_field :title %>
  </p>
  <p>
    <%= f.label :number %><br />
    <%= f.text_field :number %>
  </p>

  <p>
    Number of animals allowed on protocol:
  </p>
  <div class="left_indent">
    <table>
      <% f.fields_for :allowed_animals do |a| %>
        <tr>
          <td><i><%= a.object.species.name %></i></td>
          <td><%= a.text_field :number, :value => @protocol.determine_allowed_animals(a.object.species), :size=>2 %></td>
          <%= a.text_field :species_id, :value => a.object.species.id, :hidden => true %>
        </tr>
      <% end %>
    </table>
  </div>

  <p>
    Users on protocol:
  </p>
  <div class="left_indent">
    <%= render :partial => 'protocols/users_on_protocol_form', :locals =>{:protocol => @protocol, :users => User.current} %>
  </div>

  <p>
    <%= f.submit 'Save' %>
  </p>
<% end %>

Sign Up

Sign In

Forgot Password

The Archive Base Latest Questions

Amateur rails programmer struggling to use the fields_for form builder. My rails application (on

Leave an answerCancel reply

1 Answer

Leave an answer
Cancel reply