# Habtm

**URL:** <https://www.ruby-forum.com/t/habtm/93578>\
**Category:** Rails\
**Created:** [April 4, 2006, 9:57pm UTC](https://www.ruby-forum.com/t/habtm/93578 "2006-04-04T21:57:29Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Tobias\_Bender](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/b38774/32.png) [@Tobias\_Bender](https://www.ruby-forum.com/u/Tobias_Bender)\
**Post date:** [April 4, 2006, 9:57pm UTC](https://www.ruby-forum.com/t/habtm/93578/1 "2006-04-04T21:57:29Z")

</div>

Hi.

Im new to Ruby and new to Ruby on Rails and have problems realizing a  
simple many\_to\_many relationship:

My tables:

## items \<-\> items\_users \<-\> users

* * *

id user\_id id  
name item\_id name  
… password  
…  
My Code:

class Item \< ActiveRecord::Base  
has\_and\_belongs\_to\_many :users  
end

class User \< ActiveRecord::Base  
attr\_accessor :new\_password  
has\_and\_belongs\_to\_many :items  
[…]  
end

items/list.rhtml:  
[…]

\<%= link\_to 'Ã', :action =\> 'select', :id =\> item %\> [....]

class ItemsController \< ApplicationController  
[…]  
def select  
@user = @session[‘user’]  
item = Item.find(@params[:id])  
@user.items = Item.find(@params[:id])  
#\<\<--------this is the erroneous line of code!  
redirect\_to :action =\> ‘list’  
end  
[…]  
end

With “select” i want to add the current active user one item, whose  
id is delivered as request parameter.  
What am I doing wrong?

Thx in advance,

Tobias

NoMethodError in Items#select

undefined method `each’ for #Item:0x266b13c

RAILS\_ROOT: script/…/config/…  
Application Trace | Framework Trace | Full Trace

/dp/lib/ruby/gems/1.8/gems/activerecord-1.14.0/lib/active\_record/  
base.rb:1786:in `method_missing' /dp/lib/ruby/gems/1.8/gems/activerecord-1.14.0/lib/active_record/ associations/association_collection.rb:117:in`replace’  
/dp/lib/ruby/gems/1.8/gems/activerecord-1.14.0/lib/active\_record/  
associations.rb:884:in `items=' #{RAILS_ROOT}/app/controllers/items_controller.rb:15:in`select’

/dp/lib/ruby/gems/1.8/gems/activerecord-1.14.0/lib/active\_record/  
base.rb:1786:in `method_missing' /dp/lib/ruby/gems/1.8/gems/activerecord-1.14.0/lib/active_record/ associations/association_collection.rb:117:in`replace’  
/dp/lib/ruby/gems/1.8/gems/activerecord-1.14.0/lib/active\_record/  
associations.rb:884:in `items=' /dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action_controller/ base.rb:908:in`perform\_action\_without\_filters’  
/dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/  
filters.rb:355:in `perform_action_without_benchmark' /dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action_controller/ benchmarking.rb:69:in`perform\_action\_without\_rescue’  
/dp/lib/ruby/1.8/benchmark.rb:293:in `measure' /dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action_controller/ benchmarking.rb:69:in`perform\_action\_without\_rescue’  
/dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/  
rescue.rb:82:in `perform_action' /dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action_controller/ base.rb:379:in`process\_without\_filters’  
/dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/  
filters.rb:364:in `process_without_session_management_support' /dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action_controller/ session_management.rb:117:in`process’  
/dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/dispatcher.rb:38:in  
`dispatch' /dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick_server.rb:115:in`handle\_dispatch’  
/dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick\_server.rb:81:in  
`service' /dp/lib/ruby/1.8/webrick/httpserver.rb:104:in`service’  
/dp/lib/ruby/1.8/webrick/httpserver.rb:65:in `run' /dp/lib/ruby/1.8/webrick/server.rb:173:in`start\_thread’  
/dp/lib/ruby/1.8/webrick/server.rb:162:in `start_thread' /dp/lib/ruby/1.8/webrick/server.rb:95:in`start’  
/dp/lib/ruby/1.8/webrick/server.rb:92:in `start' /dp/lib/ruby/1.8/webrick/server.rb:23:in`start’  
/dp/lib/ruby/1.8/webrick/server.rb:82:in `start' /dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick_server.rb:67:in`dispatch’  
/dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/commands/servers/  
webrick.rb:59  
/dp/lib/ruby/vendor\_ruby/1.8/rubygems/custom\_require.rb:21:in `require' /dp/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active_support/ dependencies.rb:136:in`require’  
/dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/commands/server.rb:30  
/dp/lib/ruby/vendor\_ruby/1.8/rubygems/custom\_require.rb:21:in `require' /dp/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active_support/ dependencies.rb:136:in`require’  
script/server:3

/dp/lib/ruby/gems/1.8/gems/activerecord-1.14.0/lib/active\_record/  
base.rb:1786:in `method_missing' /dp/lib/ruby/gems/1.8/gems/activerecord-1.14.0/lib/active_record/ associations/association_collection.rb:117:in`replace’  
/dp/lib/ruby/gems/1.8/gems/activerecord-1.14.0/lib/active\_record/  
associations.rb:884:in `items=' #{RAILS_ROOT}/app/controllers/items_controller.rb:15:in`select’  
/dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/  
base.rb:908:in `perform_action_without_filters' /dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action_controller/ filters.rb:355:in`perform\_action\_without\_benchmark’  
/dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/  
benchmarking.rb:69:in `perform_action_without_rescue' /dp/lib/ruby/1.8/benchmark.rb:293:in`measure’  
/dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/  
benchmarking.rb:69:in `perform_action_without_rescue' /dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action_controller/ rescue.rb:82:in`perform\_action’  
/dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/  
base.rb:379:in `process_without_filters' /dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action_controller/ filters.rb:364:in`process\_without\_session\_management\_support’  
/dp/lib/ruby/gems/1.8/gems/actionpack-1.12.0/lib/action\_controller/  
session\_management.rb:117:in `process' /dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/dispatcher.rb:38:in`dispatch’  
/dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick\_server.rb:115:in  
`handle_dispatch' /dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick_server.rb:81:in`service’  
/dp/lib/ruby/1.8/webrick/httpserver.rb:104:in `service' /dp/lib/ruby/1.8/webrick/httpserver.rb:65:in`run’  
/dp/lib/ruby/1.8/webrick/server.rb:173:in `start_thread' /dp/lib/ruby/1.8/webrick/server.rb:162:in`start\_thread’  
/dp/lib/ruby/1.8/webrick/server.rb:95:in `start' /dp/lib/ruby/1.8/webrick/server.rb:92:in`start’  
/dp/lib/ruby/1.8/webrick/server.rb:23:in `start' /dp/lib/ruby/1.8/webrick/server.rb:82:in`start’  
/dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/webrick\_server.rb:67:in  
`dispatch' /dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/commands/servers/ webrick.rb:59 /dp/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:21:in`require’  
/dp/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/  
dependencies.rb:136:in `require' /dp/lib/ruby/gems/1.8/gems/rails-1.1.0/lib/commands/server.rb:30 /dp/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:21:in`require’  
/dp/lib/ruby/gems/1.8/gems/activesupport-1.3.0/lib/active\_support/  
dependencies.rb:136:in `require’  
script/server:3

Request

Parameters: {“id”=\>“2”}

Show session dump

* * *

user: &id001 !ruby/object:User  
attributes:  
salt: b40f4edfd113ce8c82e8283281697e8af6d09520  
delete\_after:  
role:  
security\_token: a61f0622696cdf5d4da640091f73be700ea44f5a  
id: “2”  
firstname: Tobias  
lastname: Bender  
token\_expiry: 2006-04-05 13:45:59  
deleted: “0”  
verified: “1”  
login: tbender  
salted\_password: 393e2195368915812e1490528ae3071b2f266e6f  
email: removed\_email\_address@domain.invalid  
errors: !ruby/object:ActiveRecord::Errors  
base: \*id001  
errors: {}

items: []

new\_password: false  
new\_record\_before\_save:  
return-to:  
flash: !map:ActionController::Flash::FlashHash {}

Response  
Headers: {“cookie”=\>[], “Cache-Control”=\>“no-cache”}

---

<div class="post-metadata">

**Author:** ![Tobias\_Bender](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/b38774/32.png) [@Tobias\_Bender](https://www.ruby-forum.com/u/Tobias_Bender)\
**Post date:** [April 4, 2006, 10:06pm UTC](https://www.ruby-forum.com/t/habtm/93578/2 "2006-04-04T22:06:38Z")

</div>

hi there,  
try:  
@item = Item.find(@params[:id])  
@user.items \<\< @item

since @user.items is an array in an n:n relationship you want to push  
objects on it rather than make it equal to one object… (rather crudely  
put… sorry)

kind regards,  
a

---

<div class="post-metadata">

**Author:** ![Tobias\_Bender](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/b38774/32.png) [@Tobias\_Bender](https://www.ruby-forum.com/u/Tobias_Bender)\
**Post date:** [April 4, 2006, 10:09pm UTC](https://www.ruby-forum.com/t/habtm/93578/3 "2006-04-04T22:09:09Z")

</div>

Tobias Bender wrote:

> class ItemsController \< ApplicationController  
> […]  
> def select  
> @user = @session[‘user’]  
> item = Item.find(@params[:id])  
> @user.items = Item.find(@params[:id])  
> #\<\<--------this is the erroneous line of code!  
> redirect\_to :action =\> ‘list’  
> end  
> […]  
> end
> 
> With “select” i want to add the current active user one item, whose  
> id is delivered as request parameter.  
> What am I doing wrong?
> 
> Thx in advance,
> 
> Tobias

Hi,

guess you wanted:  
@user.items\<\< item

–  
Agnieszka