I'm sure you read Frederick's response about the counter_cache being
readonly.
The way to properly populate these during a migration is to redeclare the
Learner class as an inner-class of the Migration itself, specifying only
minimal functionality.
class AddCounterCacheToLearners < ActiveRecord::Migration
class Learner < ActiveRecord::Base
def reset_column_information
# re-implement reset_column_information functionality here
end
end
def self.up
add_column :learners, :learner_sessions_count, :integer, :default => 0
Learner.reset_column_information
end
def self.down
remove_column :learners, :learner_sessions_count
end
end
On Fri, Oct 10, 2008 at 1:17 PM, Stephen Bannasch <
[EMAIL PROTECTED]> wrote:
>
> I added a counter_cache to an existing parent-child model pair and
> wanted to set all the values for the counter_cache but can't do it
> using update_attribute (or a number of other methods).
>
> Should I create a bug report?
>
> I created a simple test app in 2.2.1 to isolate the problem.
>
> # create the learner and learner_session models and migrations:
>
> script/generate model learner name:string learner_session_id:integer
> script/generate model learner_session learner_id:integer
> rake db:migrate
>
> # add the associations to the models:
>
> class Learner < ActiveRecord::Base
> has_many :learner_sessions
> end
>
> class LearnerSession < ActiveRecord::Base
> belongs_to :learner
> end
>
> # create a learner and 2 learner sessions without a counter_cache
>
> $ script/console
>
> >> l = Learner.create(:name => "stephen")
> => #<Learner id: 1, name: "stephen", learner_session_id: nil>
>
> >> l.learner_sessions.create
> => #<LearnerSession id: 1, learner_id: 1>
>
> >> l.learner_sessions.create
> => #<LearnerSession id: 2, learner_id: 1>
>
> >> l.learner_sessions.count
> => 2
>
> # now run this migration:
>
> class AddCounterCacheToLearners < ActiveRecord::Migration
> def self.up
> add_column :learners, :learner_sessions_count, :integer, :default => 0
> # Learner.reset_column_information
> end
>
> def self.down
> remove_column :learners, :learner_sessions_count
> end
> end
>
> # and add the counter_cache to the belongs_to association
>
> class LearnerSession < ActiveRecord::Base
> belongs_to :learner, :counter_cache => true
> end
>
> # back into script/console
>
> $ script/console
>
> >> l = Learner.find(:first)
> => #<Learner id: 1, name: "stephen", learner_session_id: nil,
> learner_sessions_count: 0>
>
> # there are still 2 learner sessions:
>
> >> l.learner_sessions.count
> => 2
>
> # but the learner_sessions_count is not set yet:
>
> >> l.learner_sessions_count
> => 0
>
> # update the learner_sessions_count:
>
> >> l.update_attribute(:learner_sessions_count, 2)
> => true
>
> # it is written to the model object:
>
> >> l
> => #<Learner id: 1, name: "stephen", learner_session_id: nil,
> learner_sessions_count: 2>
>
> >> l.learner_sessions_count
> => 2
>
> # but not to the database
>
> >> l = Learner.find(:first)
> => #<Learner id: 1, name: "stephen", learner_session_id: nil,
> learner_sessions_count: 0>
>
>
> >
>
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