Rails ActiveRecord querying - array from an instance variable

Question

I have 2 models, Response and Question. A question has_many responses and thus each response is associated to a question_id. I want to query the questions corresponding to the responses in the object @responses but I am unsure of the syntax.

@reponses = Response.find([1, 10])
@questions = Question.where(:id => [???])

My initial thought was something like this, but this syntax is wrong:

@reponses = Response.find([1, 10])
@questions = Question.where(:id => @responses.question_id)

Suborx · Accepted Answer · 2012-05-03 12:42:50Z

3

You was very close... Try this

@questions = Question.where(:id => @responses.map(&:question_id))

but I think you should use the scope in your Response model

answered May 3, 2012 at 12:42

Suborx

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2 Comments

Amar Over a year ago

you can also try this is same but more cleaner @questions = Question.where(:id => @responses.pluck(:question_id))

Suborx Over a year ago

I am not sure which version of rails @diasks2 is using

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