The very model of confusion with models and adding a record to joins

rubyonrails-talk
1

Hi (this is an update to a previous problem)

I've decided my fundamental problem here is a lack of understanding about models. I have enough to get my started by getting lost quickly.

So, following previous advice I have updated my models as such:

class Appointment < ActiveRecord::Base has_many :line_items belongs_to :customer end

class Customer < ActiveRecord::Base has_many :line_items has_many :appointment end

class LineItem < ActiveRecord::Base belongs_to :appointment belongs_to :customer belongs_to :therapist has_many :treatlines end

class Therapist < ActiveRecord::Base has_many :line_items end

class Treatment < ActiveRecord::Base has_many :treatlines end

class Treatline < ActiveRecord::Base belongs_to :line_item belongs_to :treatment end

I have updated my code which is trying to save lots of information in a line_items (and associated) table using the following code in my controller:

def book_appointment    # Need to write this to take in the date from the date and time boxes and    # then put it with all the rest of the information to make the appointment    # Create new appointment    @cart = find_treat    # Setup data column for the appointment    l = LineItem.new

   c = Customer.find(session[:currentcustID])    t = Therapist.find(params[:appt_therapist])    # Add a new appointment    a = Appointment.new    a.appdate = params[:appt_date]    a.apptime = params[:appt_time]    a.applength = @cart.total_time    a.customer = c

   l.appointment = a    l.customer = c    l.therapist = t    # Need to work out how to add treatments to this massive list! Refer back to book!    @cart.items.each do |item|       if Treatment.find(item.id)         tr = Treatline.new         tr.treatment = Treatment.find(item.id)         logger.warn("Treatment desclong is: #{tr.treatment.desclong}")         l.treatlines << tr       end    end    l.save

end

But I'm now getting the following error message:

ActiveRecord::StatementInvalid (Mysql::Error: Column 'treatline_id' cannot be null: INSERT INTO `line_items` (`updated_at`, `therapist_id`, `treatline_id`, `customer_id`, `appointment_id`, `created_at`) VALUES('2008-09-03 15:00:06', 2, NULL, 2, 8, '2008-09-03 15:00:06')):

I felt it would be better for each line item, to keep the treatments that each customer has in a seperate table. As each customer can have more than one treatment per visist and it'll make life easier later. Hence I've now created a table called treatline. This table would, in turn, reference the master treatments table which holds all the treatments on offer. But I have no idea how to get the line_items table to hold the id for all the treatlines I am associating with an order. If that makes sense (and it sure doesn't seem to be making much sense to me at the moment!).

It might also help to show you the LineItems model set up as well?

class CreateLineItems < ActiveRecord::Migration def self.up    create_table :line_items do |t|      t.column :treatline_id, :integer, :null => false      t.column :customer_id, :integer, :null => false      t.column :therapist_id, :integer, :null => false      t.column :appointment_id, :integer, :null => false      t.timestamps    end

   execute "alter table line_items add constraint fk_line_item_treatlines foreign key (treatline_id) references treatlines(id)"    execute "alter table line_items add constraint fk_line_item_customers foreign key (customer_id) references customers(id)"    execute "alter table line_items add constraint fk_line_item_therapists foreign key (therapist_id) references therapists(id)"    execute "alter table line_items add constraint fk_line_item_appointments foreign key (appointment_id) references appointments(id)"    execute "alter table treatlines add constraint fk_treatline_line_items foreign key (line_item_id) references line_items(id)" end

def self.down    drop_table :line_items end end

And treatlines?

class CreateTreatlines < ActiveRecord::Migration def self.up    create_table :treatlines do |t|      t.column :treatment_id, :integer, :null => false      t.column :line_item_id, :integer, :null => false      t.timestamps    end    execute "alter table treatlines add constraint fk_treatline_treatments foreign key (treatment_id) references treatments(id)"

end

def self.down    drop_table :treatlines end end

It's like being sat with a present. I think I have the right tools to get inside the wrapping, but I just can't seem to get my fingers to know they are fingers and not toes. I know my misunderstanding of models is at fault here so any help in clearing the fog and getting this to save an appointment would be great. I hate only having half the knowledge! It's driving me to drink!

Thanks in advance

Darren

2

I feel that you need to clean and simplify your model schema first.

For example i see many unnecessary complications as this:

class Appointment < ActiveRecord::Base has_many :line_items belongs_to :customer end

class Customer < ActiveRecord::Base has_many :line_items has_many :appointment end

A Customer object can have many Appointment objects associated to it and each Appointment can have many LineItems. You can access LineItems for a Customer as:

cust.appt.line_items

I don´t get why you associate directly a Customer to a LineItem. It just adds unnecessary complexity.

Next:

class LineItem < ActiveRecord::Base belongs_to :appointment belongs_to :customer belongs_to :therapist has_many :treatlines end

You also "belongs_to "associate the customer directly. This is unnecesary. The customer is linked to LineItems through Appointments.

class Therapist < ActiveRecord::Base has_many :line_items end

class Treatment < ActiveRecord::Base has_many :treatlines end

class Treatline < ActiveRecord::Base belongs_to :line_item belongs_to :treatment end

Here you have a many to many association. Each LineItem can have many Treatments and each Treatment can have many LineItems. Treatline is just a join model. I could rewrite your complete model as this:

class Customer < ActiveRecord::Base   has_many :appointment end

class Appointment < ActiveRecord::Base   has_many :line_items   belongs_to :customer end

class LineItem < ActiveRecord::Base   belongs_to :appointment   belongs_to :therapist   has_many :treatment, :through => :treatline end

class Therapist < ActiveRecord::Base   has_many :line_items end

class Treatment < ActiveRecord::Base has_many :line_items, :through => :treatline end

class Treatline < ActiveRecord::Base belongs_to :line_item belongs_to :treatment end

Just add line_item_id and treatment_id to your treatlines table, so the associations can be handled correctly, and delete the unnecessary _id columns from your other tables.

And voilá!

You can do this:

cust = Customer.find(*** customer id ***) app = Appointment.create(*** whatever extra appoinment attributes you have ***)

li = LineItem.create(:therapist_id => therapist_id, *** more attributes ***)

or you can do it in two lines, but more readable:

li = LineItem.create(*** line item atributes) li.therapist << Therapist.find(*** Theraphist ID ***)

li.treatments << Treatment.find(*** treatment _id***) li.treatments << Treatment.find(*** another_treatment_id ***) app.line_item << li

cust.appointment << app

You just created a complete appointment for your customer This is not tested code, so it may not work at all, but it will give you a rough idea of what can be accomplished with proper associations.

Hope it helps.

Regards, Jorge Corona.

3

I forgot to associate the treatlines table. The models will be like this:

class Customer < ActiveRecord::Base   has_many :appointment end

class Appointment < ActiveRecord::Base   has_many :line_items   belongs_to :customer end

class LineItem < ActiveRecord::Base   has_many :treatline   belongs_to :appointment   belongs_to :therapist   has_many :treatment, :through => :treatline end

class Therapist < ActiveRecord::Base   has_many :line_items end

class Treatment < ActiveRecord::Base has_many :treatline has_many :line_items, :through => :treatline end

class Treatline < ActiveRecord::Base belongs_to :line_item belongs_to :treatment end

Regards, Jorge Corona.