Rails 3: Filtering and scopes "cant convert hash to integer" problem

I have a "course" model, which has_many timeslots.

In the courses model, I have the following methods:

def available_timeslots
  tsar开发者_JS百科ray = []
  self.timeslots.map{ |t|
    if t.available then
      tsarray << t
    end
  }
  tsarray
end

def earliest_slot
  self.available_timeslots.first(:order => :starting_date)
end

What I'm trying to do now is get the earliest available timeslot for each course. Without the availability filter, @course.earliest_slot works fine. But if I try @course.available_timeslots.earliest_slot brings back a "can't convert hash into integer" message.

Any suggestions appreciated

Zabba's comment is right on the money. The available_timeslots method is returning an Array and you are calling the method first on that -- but that is not the same as calling the method first on the object that a Rails association returns.

I think you want to use scopes. So delete your available_timeslots method and add this to your Timeslot class:

scope :available, where(:available => true)

then in your earliest_slot method you can do

self.timeslots.available.first(:order => :starting_date)

and it will return the first available timeslot for the course referred to by 'self'.

(Note: I am making the assumption that 'available' is a boolean. If it is something else, change the where condition in the scope appropriately.)