What I'm doing wrong, has_and_belong_to_many

Hello, I’m trying to insert into my migrate but when I try on rails
console this error shows:

1.9.3-p0 :001 > group = Group.new
=> #<Group id: nil, name: nil, description: nil, created_at: nil,
updated_at: nil>
1.9.3-p0 :002 > group.name = “Group Name”
=> “Group Name”
1.9.3-p0 :003 > group.description = “Description”
=> “Description”
1.9.3-p0 :004 > group.save
(0.2ms) BEGIN
SQL (0.4ms) INSERT INTO groups (created_at, description,
name, updated_at) VALUES (‘2012-02-14 01:39:22’, ‘Description’,
‘Group Name’, ‘2012-02-14 01:39:22’)
(124.5ms) COMMIT
=> true
1.9.3-p0 :005 > email = Email.new
=> #<Email id: nil, name: nil, email: nil, sex: “M”, created_at: nil,
updated_at: nil>
1.9.3-p0 :006 > email.name = “Gremio10”
=> “Gremio10”
1.9.3-p0 :007 > email.email = “[email protected]
=> “[email protected]
1.9.3-p0 :008 > email.save
(0.2ms) BEGIN
SQL (0.5ms) INSERT INTO emails (created_at, email, name,
sex, updated_at) VALUES (‘2012-02-14 01:39:56’, ‘[email protected]domain.invalid’,
‘Gremio10’, ‘M’, ‘2012-02-14 01:39:56’)
(65.6ms) COMMIT
=> true
1.9.3-p0 :009 > group << email
NoMethodError: undefined method <<' for #<Group:0xa7efb80> from /home/felipe/.rvm/gems/ruby-1.9.3-p0/gems/activemodel-3.2.1/lib/active_model/attribute_methods.rb:407:inmethod_missing’
from
/home/felipe/.rvm/gems/ruby-1.9.3-p0/gems/activerecord-3.2.1/lib/active_record/attribute_methods.rb:126:in
method_missing' from (irb):9 from /home/felipe/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.1/lib/rails/commands/console.rb:47:instart’
from
/home/felipe/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.1/lib/rails/commands/console.rb:8:in
start' from /home/felipe/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.1/lib/rails/commands.rb:41:in<top (required)>’
from script/rails:6:in require' from script/rails:6:in
1.9.3-p0 :010 >

My EmailModel

class Email < ActiveRecord::Base
has_and_belongs_to_many :groups
validate :email
end

My GroupModel

class Group < ActiveRecord::Base
has_and_belongs_to_many :emails
validate :name
end

My GroupsMigrate

class CreateGroups < ActiveRecord::Migration
def change
create_table :groups do |t|
t.string “name”
t.string “description”
t.timestamps
end
end

def down
drop_table :groups
end
end

My EmailsMigrate

class CreateEmails < ActiveRecord::Migration
def change
create_table :emails do |t|
t.string “name”
t.string “email”
t.string “sex”, :default => “M”, :limit => 1
t.timestamps
end
end

def down
drop_table :emails
end
end

My EmailsGroupsMigrate

class CreateEmailsGroupsJoin < ActiveRecord::Migration
def up
create_table :emails_groups, :id => false do |t|
t.references :email
t.references :group
end

add_index :emails_groups, [ "email_id", "group_id" ]

end

def down
drop_table :emails_groups
end
end

Thank you.

On Mon, Feb 13, 2012 at 20:43, Felipe Pieretti U.
[email protected] wrote:

Hello, I’m trying to insert into my migrate but when I try on rails
console this error shows:

1.9.3-p0 :009 > group << email
NoMethodError: undefined method `<<’ for #Group:0xa7efb80

This is the chunk you need to worry about. It’s telling you that you
haven’t defined any << method for your Group model. AR doesn’t
provide one, as such a thing just wouldn’t make sense for most models.

class Email < ActiveRecord::Base
has_and_belongs_to_many :groups
validate :email
end

class Group < ActiveRecord::Base
has_and_belongs_to_many :emails
validate :name
end

You may also want to consider using “has_many :through” rather than
has_and_belongs_to_many. I’ve heard horror stories of people having
trouble getting HABTM to work right (though I never had problems with
it myself), and if you ever decide you want to “decorate” that
relationship with any additional data, it can be very difficult to
retrofit a HABTM relationship to become HMT.

-Dave


Dave A.: Available Cleared Ruby on Rails Freelancer
(NoVa/DC/Remote) – see www.DaveAronson.com, and blogs at
www.Codosaur.us, www.Dare2XL.com, www.RecruitingRants.com

If I don’t have the method ‘<<’, how can I install on my rails ?

My error:

I was doing this -> group << email

But the correct is doing this -> group.emails << email

Thank you

If you have a has_many relationship or if you have any collection, you
will
be able to use the append method << .

att

2012/2/14 Felipe Pieretti U. [email protected]

[email protected]
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.


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