I have a model that I'd like to scope based on an associated model. Here are the models, ClassSection and ClassDate.
class ClassSection < ActiveRecord::Base
has_many :class_dates
accepts_nested_attributes_for :class_dates, allow_destroy: true
def begins
self.class_dates.order('start_time ASC').limit(1).first.start_time
end
def ends
self.class_dates.order('end_time DESC').limit(1).first.end_time
end
end
Each ClassDate has two datetime values, :start_time and :end_time.
class ClassDate < ActiveRecord::Base
belongs_to :class_section
validates :start_time, :presence => true
validates :end_time, :presence => true
validate :end_time_must_be_greater_than_start_time,
:end_time_must_not_be_greater_than_24_hours_after_start_time
def end_time_must_be_greater_than_start_time
if start_time > end_time
errors.add(:end_time, "End time must be after start time.")
end
end
def end_time_must_not_be_greater_than_24_hours_after_start_time
if start_time < end_time - 1.day
errors.add(:end_time, "End time cannot be more than 24 hours after start time.")
end
end
end
I want a scope called :in_session where today's date falls in between class_section.begins and class_section.ends. This does not work:
scope :in_session, where(class_section.begins < Time.now) && where(class_section.ends > Time.now)
Is it possible to scope using either the methods I've written or through the association with ClassDate? What would be the most efficient way to do this?
Yes it's possible. In Rails 4 however, you need to use lambda scope and not eagerly load the conditions as you've done.
Try:
scope :in_session, -> { joins(:class_section).where('? between class_sections.begins and class_sections.ends', Time.now) }
Your table name class_section
is singular as you've shown your scope, it should be plural class_sections
unless you've explicitly specified it to be singular. I've used plural class_sections
in the scope above, update it to singular class_section
if your table name is singular.
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