Vfrdtyky

I've made a scheduling app where people are assigned to rooms each day. On Thursdays someone must be assigned for 'pager pickup' and I'm having problems with the validation to check for that.

Model

class Schedule < ActiveRecord::Base 

  has_many :rooms

  ...

  validate :thursday_schedule_must_have_pager_pickup

  ...



  def add_rooms

    return unless self.rooms.count == 0                           

    n = 1

    tomorrow = DateTime.tomorrow                                  

    Schedule.site_list.each do |site|                             

      Schedule.const_get(site).each do |room|                     

        self.rooms.build(order: n,                                

                      site: site.to_s,                         

                      name: room,

                      start_hour: get_start_hour(tomorrow),    

                      start_minute: get_start_minute(tomorrow, site.to_s))                   

        n += 1                                                    

      end

    end

    self.add_pager_pickup(n, tomorrow) if true # self.for_thursday?

    self.add_today_call_data(n) if no_call_data                   

  end

...

def add_pager_pickup(order, tomorrow)

  self.rooms.build(order: order,

      site: "TSH",

      name: "Pager Pickup",

      start_hour: 7,

      start_minute: get_start_minute(tomorrow, "TSH"))

  end

end



class Room < ActiveRecord::Base

  belongs_to :schedule

  ...

end

The code I'd like to write is:

def thursday_schedule_needs_pager_pickup

  if self.for_thursday? && self.rooms.where(name: "Pager Pickup").first.initials.blank?

    errors.add(:rooms, "'Pager Pickup' can't be empty.  Select '-- late start' if no one should come in early to pick up pager.")

  end

end

That generates the following errors:

NoMethodError in SchedulesController#create

undefined method `initials' for nil:NilClass

By adding the "Pager Pickup" room to the schedule last I can hack a validation with the following code:

... self.rooms.last.initials.blank?

But that's brittle and preventing me from adding a 2nd, optional, pager pickup person, "2nd Pager Pickup", after the first.

Per Julien's points:

Schedule Controller

class SchedulesController < ApplicationController 

...

  def new

    s = current_user.schedules.new

    s.add_rooms

    @schedule = s

  end



  def create 

    @schedule = current_user.schedules.build(schedule_params)

    if @schedule.save 

      flash.now[:success] = "Draft Schedule Saved! Now Confirm or Edit."

      render :show

    else

    render :new

  end

...

end

Anyone have any thoughts?

Thanks in advance!

If I'm reading your code correctly, you have an unsaved object and you're trying to run this validation on it:

self.rooms.where(name: "Pager Pickup").first.initials.blank?

The problem with this approach is that .where on association will run a database query (or to be specific, it'd run the query if your objects were saved, but will do nothing for unsaved relations). This won't work for you, you haven't saved anything yet, you have to operate on objects in memory. If you change that line to:

self.rooms.detect {|r| r.name == "Pager Pickup" }.initials.blank?

it should work but it is still prone to errors if you simply leave it in your model, as in another context there might not be a room with that name and .initials will still be called on nil. I'd suggest you move such logic to factory objects, where you can strictly tie your validations to the context.

In order to fully understand the concept, you may run this in rails console:

s = Schedule.new

# => #<Schedule id: nil>

s.rooms << Room.new(foo: "bar")

# => #<ActiveRecord::Associations::CollectionProxy [#<Room id: nil, schedule_id: nil, foo: "bar">]>

s.rooms.where(foo: "bar")

# => #<ActiveRecord::AssociationRelation >

s.rooms.detect { |r| r.foo == "bar" }  

# => #<Room id: nil, schedule_id: nil, foo: "bar">

Note: Your "hack" with .last worked because it operated on an array, not an ActiveRecord::Relation.

The problem that you are facing is that you are trying to do a query on a model that is not yet saved into the database. It does not have an id and the associated models rooms do not yet have an id themselves either.

Your validation throws an error because .where calls the database and it can't find the models, as they currently live only in memory.

self.rooms.where(name: "Pager Pickup").first.initials.blank?

However, you have the information on both models to do the validation correctly, you are just looking for it in the wrong place.

If you debug your app so that your instance of Schedule is built (not saved yet) and you add some rooms to it (not yet saved either), you will see the following behavior:

@schedule.rooms.length # It will be some value bigger than 0



@schedule.rooms.count # It will be zero

Why? Because .length works on the object as an array and .count searches for it in the database. As I mentioned before, your models do not exist on the DB so it wont find them, but they are in memory so you can measure the length of it.

The change you need to do in this problem is to imitate what .where does but in memory, with a simple .select:

self.rooms.select { |r| r.name == 'Pager Pickup' }.first.initials.blank?

That is the only change you need to do, but you should understand why.

Ok so first of all

self.rooms.where(name: "Pager Pickup") 

is potentially going to return multiple objects so it doesn't give you a Room object but probably an ActiveRecord::Relation object so you would need to add something like .first before .initials to get a Room like so:

self.rooms.where(name: "Pager Pickup").first.initials.blank?

But anyway the error states that it is not finding anything so it seems that at the time of validation the rooms relationship for this schedule doesn't exist or is "empty" since it is claiming nil is returned from that query instead of an empty array so i'm guessing that your validation occurs before the room is actually created/saved.

Maybe show us the create action of the SchedulesController to see if something is wrong there.

UPDATE

After seeing your extra code, the problem is that you are calling add_rooms to a different schedule object than the one you are creating, I'm guessing your are on the impression that instance variables (variables starting with @) are persisted between requests but they are not, so the @schedule object in your create action is not the same one as in your new action therefore it doesn't have any rooms yet, update your create action to populate the rooms of that object doing something like this:

  def create 

    @schedule = current_user.schedules.build(schedule_params)

    @schedule.add_rooms    # <-- Add this line

    if @schedule.save 

      flash.now[:success] = "Draft Schedule Saved! Now Confirm or Edit."

      render :show

    else

    render :new

  end