scopes with lambda and arguments in Rails 4 style?

Question

I\'m wondering how the following is done in Rails 4 or if I just use the Rails 3 approach for using a lambda that can pass an argument the same way with 4 as I do with 3.

Answer 1

scope :find_lazy, -> (id) { where(id: id) }

is equivalent with

self.find_lazy(id)
  where(id: id)
end

Based on ruby on rails guide: Using a class method is the preferred way to accept arguments for scopes.

There is no reason to use scopes together with lambdas in preference to class methods. It is a matter of personal preference. But, if you want to follow the guidelines, you should use the class method when arguments are involved.

Answer 2

guy I was usually using the below programming syntax

scope :find_lazy, -> (id) { where(id: id) }

But when I was reviewing my code using Codacy I found it alerting me about this syntax

Use the `lambda` method for multiline lambdas.

I changed it to be and it working well

  scope :find_lazy, lambda {|id|
    where(id: id)
  }

Answer 3

I think it should be:

scope :find_lazy, -> (id) { where(id: id) }

Answer 4

To support associations:

scope :find_lazy, -> (object) { where(object_id: object.id) }

Answer 5

Rails 4, you can do:

scope :find_lazy, -> (id) { where(id: id) }

That was in the old ruby:

:id => id

Better hash:

id: id

Answer 6

Ruby has not deprecated the old style of lambda either, so if you feel more comfortable using that by all means go for it.

I don't personally like the stabby lambda's syntax myself but eventually they will probably become the norm so it doesn't hurt to get used to them.