using if with scope on model

Question

I am trying to make a named scope called :current_season where the it will correctly identify the records associated with the year we are in. Mostly easy enough except I want everything June and later to use the current year and everything prior to June to use the previous year.

in rails 3.1 I can easily use:

scope :current_season, lambda { where('season = ?',Time.now.year) } if Time.now.month >= 6

to get the scope to only work if we are at the end of the year and :

scope :current_season, lambda { where('season = ?',Time.now.year - 1) } if Time.now.month < 6

But it seems to wasteful to have to name it all twice and not use an if/else type of thing or be able to call in something I define below to show the exact year such as:

scope :current_season, lambda { where('season = ?',:current_season_year) } 

def current_season_year
  if Time.now.month >= 6
    Time.now.year
  else
    Time.now.year - 1
  end
end

But that just laughs at me when I try it. Is there a cleaner way? I will also have a scope :last_season and scope :previous_season most likely and they will follow similar logic.

thanks in advance for any advice!

Answer 1

Named scopes are just a DSL for writing a class methods that all have a similar functionality. Whenever you find them to be limiting you, just switch to a class method instead:

def self.current_season
  year = Time.now.month >= 6 ? Time.now.year : Time.now.year - 1
  where('season = ?', year)
end

Of course, you could also include that in a scope like this:

scope :current_season, do
  # same code as above...
end

It's just going to define it as a class method on the model though. The tradeoff is clarity in the intention of a scope (it's expected to return a chainable ActiveRecord::Relation) versus clarity in documentation (if you run something like RDoc it isn't going to notice a method available at Model.current_season because it hasn't been defined in the code yet).

Update:

There is one additional benefit from using a scope instead of a class method:

User.admin.create name: 'Corey'  #=> <User: @name="Corey" @admin=true>

You can use a scope to create an object with certain parameters, as well. In this case, this isn't very useful, but it's worth considering when deciding which to use.