CODEWITHSUNDEEP
ruby-on-rails
mrfred
mrfred

Reputation: 631

Rails assignment on a one-to-one relationship

Alright, so I'm trying to connect a Profile object to a Session object through a one to one relationship. The way I understand it is if I have the relationship set up properly, the following is equivalent (please correct me if I'm wrong)

@my_session << @my_profile

@my_session.profile = @my_profile

@my_session.profile_id = @my_profile.id

I have the following set up in my models folder

profile.rb:

class Profile < ActiveRecord::Base
    has_one :session

session.rb:

 class Session < ActiveRecord::Base
    # I tried this without foreign_key also, it works the same
    belongs_to :profile, :foreign_key => 'profile_id'

And in my database tables, session has profile_id in it

Doing the following two commands in my rails console works fine:

@my_session.profile = @my_profile

@my_session.profile_id = @my_profile.id

However, whenever I try to do the following:

@my_session << @my_profile

I get an error

NoMethodError: undefined method `<<' for #<Session:0x00000004a26198>
from /.../rubies/ruby-2.2.2/lib/ruby/gems/2.2.0/gems/activemodel-4.2.3/lib/active_model/attribute_methods.rb:433:in `method_missing'

Is this some sort of problem with how I have rails setup or something? Any help would be great. Thanks.

Upvotes: 1

Views: 529

Answers (1)

xkickflip
xkickflip

Reputation: 768

When declaring a has_one association on an ActiveRecord model it gains the following methods:

association(force_reload = false)
association=(associate)
build_association(attributes = {})
create_association(attributes = {})
create_association!(attributes = {})

Which does not include the shovel operator << thus your error that << is undefined in this case. It's not a configuration problem. Looks like your config is working fine. Here's the Rails guide with the specific details

http://guides.rubyonrails.org/association_basics.html#has-one-association-reference

The << shovel operator is defined along with all these other methods when you include a has_many or has_and_belongs_to_many on a model:

collection(force_reload = false)
collection<<(object, ...)
collection.delete(object, ...)
collection.destroy(object, ...)
collection=(objects)
collection_singular_ids
collection_singular_ids=(ids)
collection.clear
collection.empty?
collection.size
collection.find(...)
collection.where(...)
collection.exists?(...)
collection.build(attributes = {}, ...)
collection.create(attributes = {})
collection.create!(attributes = {})

Here's the details:

http://guides.rubyonrails.org/association_basics.html#has-many-association-reference

http://guides.rubyonrails.org/association_basics.html#has-and-belongs-to-many-association-reference

Upvotes: 1

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