two tables, users and languages,
one user may have many languages, one language may belong to many users.
so, I create the joint table users_languages with user_id and
language_id only.
class User < ActiveRecord::Base
has_and_belongs_to_many :languages
end
class Language < ActiveRecord::Base
has_and_belongs_to_many :users
end
class UsersLanguages < ActiveRecord::Base
belongs_to :users
belongs_to :languages
end
I also create one sample user data into users tables and one sample
language data into languages table. nothing in joint table
users_languages.
then, I go to console to test:
if I use the following code, everything is fine.
l=Language.new
u=User.new
u.languages << l
but when I use the real data, still under console,
l=Language.find(1)
u=User.find(1)
u.languages << l
when I am at the third line, I will get an error message like this:
ActiveRecord::StatementInvalid: PGError: ERROR: relation
"languages_users" does not exist
: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
d.adsrc, a.attnotnull
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = ''languages_users''::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
any reason for that? thanks for any help.
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Surfman Joe wrote:> class UsersLanguages < ActiveRecord::Base > belongs_to :users > belongs_to :languages > end >Rails expects the join table to be named languanges_users. Also, you don''t want a model for this table, you simple create a migration: class LanguagesUsers < ActiveRecord::Migration def self.up create_table :languages_users, :id => false do |t| t.column :language_id, :integer, :null => false t.column :user_id, :integer, :null => false end end def self.down drop_table :languages_users end end -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Drew Olson wrote:> Rails expects the join table to be named languanges_users. Also, you > don''t want a model for this table, you simple create a migration: > > class LanguagesUsers < ActiveRecord::Migration > def self.up > create_table :languages_users, :id => false do |t| > t.column :language_id, :integer, :null => false > t.column :user_id, :integer, :null => false > end > end > > def self.down > drop_table :languages_users > end > endThanks. It fixes my problem. I am totally new to ROR, how can I know when I have to use languages_users rather than users_languages? Is there any tutorial for naming convention? thanks. -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
> I am totally new to ROR, how can I know when I have to use > languages_users rather than users_languages?It''s based on which word comes first in the alphabet, hence languages_users rather than users_languages. -Drew -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Yes. There are tons of tutorials, books, and such. Also there is always the Rails and Ruby API. Agile web development with rails has an excellant chapter on relationship so does the RoR website''s How To section. On Feb 20, 9:04 am, Surfman Joe <rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> Drew Olson wrote: > > Rails expects the join table to be named languanges_users. Also, you > > don''t want a model for this table, you simple create a migration: > > > class LanguagesUsers < ActiveRecord::Migration > > def self.up > > create_table :languages_users, :id => false do |t| > > t.column :language_id, :integer, :null => false > > t.column :user_id, :integer, :null => false > > end > > end > > > def self.down > > drop_table :languages_users > > end > > end > > Thanks. It fixes my problem. > > I am totally new to ROR, how can I know when I have to use > languages_users rather than users_languages? > > Is there any tutorial for naming convention? thanks. > > -- > Posted viahttp://www.ruby-forum.com/.--~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---