Question

I have two model A and B. A has_many B’s. B has an attribute :number

What is the rails way (I could do some coding with each, but that’s not the point) to find if an A has a B object with a given number ?

I’ve tried find but since it’s an association, it gives me this error:

>> bs.find{|f| f.number == 8}
>> ActiveRecord::RecordNotFound: Couldn't find A without an ID

EDIT

To make more clear.

If I had to code this would be something like:

def is_number_in_use(number)?
    self.bs.each do |b| #Consider bs as the has_many association between A and B
        return true if b.numero == number
    end
    return false
end

Answer 1

Is that better?

a.bs.select{ |b| b.number == 8 }.any? #=> return true if a has one b o more with number == 8