Creating a scope with a query from a method on Ruby on Rails

Question

Im trying to create a scope on a Model at my project, but I want that the query filter the elements basead on a method at my Model.

This is my model:

class Talent < ApplicationRecord
  scope :public_profile, -> { Talent.all.select{ |t| t.age > 13 } }

def age
  now = Time.now.utc.to_date
  now.year - self.birth_date.year - ((now.month > self.birth_date.month || 
  (now.month == self.birth_date.month && now.day >= self.birth_date.day)) ? 0 : 1)
end

When I try to run this scope I get the error:

 NoMethodError: undefined method `year' for nil:NilClass
    from app/models/talent.rb:195:in `age'
    from (irb):6:in `block in irb_binding'
    from (irb):6

The line 195 its on my method age. So, probably when doing the select, my element is coming nil.

What Im doing wrong here?

jvillian · Accepted Answer · 2019-03-07 18:40:00Z

2

Given:

NoMethodError: undefined method `year' for nil:NilClass

And given that you're only calling the method year twice in the age method:

def age
  now = Time.now.utc.to_date
  now.year - self.birth_date.year - ((now.month > self.birth_date.month || 
  (now.month == self.birth_date.month && now.day >= self.birth_date.day)) ? 0 : 1)
end

And given that now is certain not to be nil:

now = Time.now.utc.to_date

It would seem that self.birth_date is returning nil. And, as the error states, nil doesn't have the year method.

answered Mar 7, 2019 at 18:40

jvillian

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3 Comments

Fernando Maymone Over a year ago

Exactly. So, the scope of self doesnt work when called from a scope? Should I create a method with a paramether and pass the object to the method?

engineersmnky Over a year ago

@FernandoMaymone this has nothing to do with the scope of self this has to do with the fact that one of your records does not have a birth_date. That being said select will return an Array and a scope should always return an ActiveRecord::Relation so that is going to cause an issue

Fernando Maymone Over a year ago

Exactly. The problem was the birth_date comming nil. Thanks guys

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