Question

I am trying to do a basic belongs_to/has_many association but running into a problem. It seems that the declaring class’s foreign key column is not being updated. Here are my models:

#
# Table name: clients
#
#  id         :integer         not null, primary key
#  name       :string(255)
#  created_at :datetime
#  updated_at :datetime
#

class Client < ActiveRecord::Base
  has_many :units
  ...
  attr_accessible :name
end

#
# Table name: units
#
#  id         :integer         not null, primary key
#  client_id  :integer
#  name       :string(255)
#  created_at :datetime
#  updated_at :datetime
#

class Unit < ActiveRecord::Base
  belongs_to :client
  ...
  attr_accessible :name
end

When I open rails console I do the following:

#This works as it should
c1 = Client.create(:name => 'Urban Coding')
u1 = c1.units.create(:name => 'Birmingham Branch')

The above gives me the correct results. I have a client and a unit. The unit has the client_id foreign key field populated correctly.

#This does not work.
c1 = Client.create(:name => 'Urban Coding')
u1 = Unit.create(:name => 'Birmingham Branch')

u1.client = c1

I feel the above should have the same effect. However this is not the case. I have a unit and a client but the units client_id column is not populated. Not sure exactly what I am doing wrong here. Help is appreciated. Let me know if you need more information.

Answer 1

You’re simply not saving u1, hence no change to the database.

If you want it assigned and saved in a single operation, use update_attribute

u1.update_attribute(:client, c1)