At the end of the day, the most important thing is that it works. However, I
think we should try to get the database do the work. I'll apologize in advance
that this example is rails2.
# Project -> TaskList -> Task
Project.all(:group => "projects.id", :joins => {:task_lists => :task},
:conditions => "tasks.status = 'open'")
This results is a list of projects that have open tasks.
Luke
On 2010-10-15, at 6:17 AM, AppleII717 wrote:
> I guess I have to chalk to up to another "I didn't know you could do
> that". I'll also admit I have no idea how efficient this is.
>
> I've used a technique where I query a belongs_to table with the ids of
> a has_many related table. In my test I have
> Assessments has_many -> Questions has_many -> Answers
>
> I'd do something like
> answer_ids = Answer.where(:requires_other =>
> true).select(:question_id).map(&:question_id)
> # @foo.map(&:id) is shorthand for @foo.map{|i| i.id}, which gets
> array of ids
> question_ids = Question.where(:id =>
> answer_ids).select(:assessment_id).map(&:assessment_id)
> @assessments = Assessment.where(:id => question_ids)
>
> Or, if you want one big hard to read statement!
>
> @assessments = Assessment.where(:id => Question.where(:id =>
> Answer.where(:requires_other =>
> true).select(:question_id).map(&:question_id)).select(:assessment_id).map(&:assessment_id))
>
> Someone else will have to chime in on how efficient or inefficient
> this is. My last project was on a database that was very reliant on
> "sets" and this is the closest thing I've found in rails to that
> concept.
>
> Steve
>
> On Oct 15, 7:00 am, Max Reznichenko <[email protected]> wrote:
>> Hi, everyone.
>>
>> Yesterday found an interesting issue in scope method.
>> Let`s say, you have next model structure:
>>
>> Model A --has_many-> Model B --has_many-> Model C --has_many-> Model_D
>>
>> Model D has some attribute, let`s say, 'status' ENUM('opened',
>> 'closed').
>>
>> In Model A I would like to take all records, where Model D`s status is
>> opened.
>> This is a little bit confusing.
>>
>> Here is an example.
>> We have a project. A project has many tasklists. Tasklist has many
>> tasks.
>> I would like take all projects, which have one or more tasks opened.
>> I hope, there should be any possibility to call in controller just
>> active_projects = Project.all.active.
>>
>> I would appreciate any help.
>>
>> Max Reznichenko
>>
>> --
>> Posted viahttp://www.ruby-forum.com/.
>
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