CODEWITHSUNDEEP
ruby-on-railsruby
D.Deriso
D.Deriso

Reputation: 4397

Collection Method within Rails Model gets error NoMethodError: undefined method `collect'

I'm having trouble applying a method to a collection within a model. Here's what my model looks like:

class MyModel < ActiveRecord::Base
  def self.range(min, max)
    where(id: min..max)
  end

  def self.my_collection_method
    collect{|x| x.id}
  end
end

This works:

MyModel.range(53, 55)
# [#<MyModel id: 53>, #<MyModel id: 54>]

And this works:

MyModel.range(53, 55).collect{|x| x.id}
# [53, 54]

But when I try to be fancy and use my_collection_method instead of collect, I get this error:

MyModel.range(53, 55).my_collection_method
# NoMethodError: undefined method `collect' for #<Class:0x007fcbad3efc30>

How can I get this to work?

Thanks for your time and wisdom!!

Upvotes: 0

Views: 2451

Answers (2)

jvnill
jvnill

Reputation: 29599

I don't know what you're trying to achieve but you should be able to use it when you call scoped first

def self.my_collection_method
  scoped.collect {|x| x.id}
end

without scoped, you are trying to call self.collect which is not a method of ActiveRecord models. having scoped there means you want to apply collect to the current chain.

Upvotes: 3

Jon Cairns
Jon Cairns

Reputation: 11951

You've defined my_collection_method on the model, not on a collection - they are separate classes. You can normally achieve what you want to do inside a model method:

class MyModel < ActiveRecord::Base
  def self.range(min, max)
    where(id: min..max)
  end

  def self.my_collection_method(min, max)
    range(min, max).collect{|x| x.id}
  end
end

The only other way is by attaching a method on the fly to the collection, but that's going to be pretty ugly.

Upvotes: 2

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