Joining Three tables in Rails3 - ruby-on-rails-3

I am using http://guides.rubyonrails.org/ to learn ruby & rails. I have problem with joining three tables. , so I made new project as this example: http://guides.rubyonrails.org/association_basics.html#the-has_many_through-association i have three tables physicians, appointments & patients
Models:
physician.rb
class Physician < ActiveRecord::Base
has_many :appointments
has_many :patients, :through => :appointments
attr_accessible :name
end
appointment.rb
class Appointment < ActiveRecord::Base
belongs_to :physician
belongs_to :patient
attr_accessible :appointment_date, :patient_id, :physician_id
end
patient.rb
class Patient < ActiveRecord::Base
has_many :appointments
has_many :physicians, :through => :appointments
attr_accessible :name
end
I want to display the patient name, physician name & appointment_date. how to do this.
thanks in advance.


I believe, although I am not sure, that you are looking for the way to access objects and their associations in views. Is that correct?
I will give you an example using the Appointment model.
AppointmentsController
class AppointmentsController < ApplicationController
def index
#appointments = Appointment.includes(:physician, :patient).order(:appointment_date)
end
end
appointments#index (Haml syntax)
%ul
- #appointments.each do |appointment|
%li
= appointment.appointment_date
%br
%strong Physician:
= link_to appointment.physician.name, appointment.physician
%br
%strong Patient:
= link_to appointment.patient.name, appointment.patient
This would give you a list of appointments with their dates, physicians, and patients.
Is this the sort of help for which you were looking?


In Appointment Controller:
def index
#appointments = Appointment.order("appointment_date DESC")
end
In Appointments#index
<% for appointment in #appointments %>
<%= link_to appointment.patient.name, patients_path(appointment.patient) %>
Appointment for
<%= link_to appointment.physician.name, physician_path(appointment.physician) %>
<% if appointment.appointment_date? %>
<%= appointment.appointment_date %>
<% end %>
<% end %>

Related

Grouping posts by user in has_many through relation collection with Rails 5

I'm trying to display Users (devise) in a collection (has_many through).
<%= #collection.posts.count %> designs by
<% #collection.posts.each do |post| %>
<%= link_to image_tag(post.designer.avatar.url.to_s, class: "avatar-small"), post.designer %>
<% end %>
but it displaying duplicates as in
I need to group by designer.id. So I added #collection_designers line but I could not manage to group by designer id.🤷‍♂️
class CollectionsController < ApplicationController
def show
#collection = Collection.find(params[:id])
#I need to group for designer.id I guess but I could not manage it
#collection_designers = Collection.find(params[:id]).groups(designers.id)
end
...
Relations:
models/collection.rb
class Collection < ApplicationRecord
belongs_to :designer
has_many :collectivizations
has_many :posts, through: :collectivizations
end
models/collectivization.rb
class Collectivization < ApplicationRecord
belongs_to :post
belongs_to :collection
end
models/post.rb
class Post < ApplicationRecord
belongs_to :category
belongs_to :designer
has_many :collectivizations
has_many :collections, through: :collectivizations

You need to find uniq designers ids at first
designer_ids = #collection.posts.distinct.pluck(:designer_id)
And after it find designers by these ids
#designers = Designer.where(id: designer_ids)

why are my new and create actions not working with accepts_nested_attributes_for with has_many through?

I'm building a rail 3.2.16 app using 3 models related with a has_many through association but my saving actions are not working. this are my models:
class Cliente < ActiveRecord::Base
has_many :prestamos
accepts_nested_attributes_for :prestamos, reject_if: :all_blank
end
class User < ActiveRecord::Base
has_many :prestamos
has_many :clientes, :through => :prestamos
end
class Prestamo < ActiveRecord::Base
validates_numericality_of :monto, only_integer: true
validates :monto, presence: true
belongs_to :user
belongs_to :cliente, inverse_of: :prestamos
end
When I try to build my #cliente in clientes_controller#new with this
#cliente = current_user.clientes.build
and this in #create
#cliente = current_user.clientes.build(params[:cliente])
and using this view
<%= simple_form_for(#cliente) do |f| %>
<%= f.input :nombre %>
<%= f.input :cedula %>
<%= f.input :direccion %>
<%= f.simple_fields_for :prestamos do |builder| %>
<%= builder.input :monto %>
<% end %>
<%= f.button :submit %>
<% end %>
The render HTML is the expected one, but on save I got the validations errors related to monto in prestamo model. By the way, the monto field is displayed twice.
The erros I having:
Prestamos monto is not a number
Prestamos monto can't be blank
I really hope someone can help me.
Thanks in advance.

Well, I could solve it, but I'm not sure if this is the best way to do it since I'm pretty new in Rails (3 month). This is what I did:
First, I changed my join model Prestamo to this:
class Prestamo < ActiveRecord::Base
attr_accessible :monto, :user_id, :cliente_id
validates_numericality_of :monto, only_integer: true
validates :monto, presence: true
belongs_to :user
belongs_to :cliente, inverse_of: :prestamos
end
The validation were there already, I just added :user_id to the attr_accessible.
2nd, I changed my new and create actions to this:
new:
def new
#cliente = Cliente.new
#cliente.prestamos.build(user_id: current_user.id)
end
create:
#cliente = Cliente.new(params[:cliente])
Finally, I added a hidden field to my form just to store the user_id
<%= form.simple_fields_for :prestamos do |f| %>
<%= f.input :monto %>
<%= f.input :user_id, as: :hidden %>
<% end %>

Form not displayed correctly

i have a form consists of the following models
Employee.rb
class Employee < ActiveRecord::Base
attr_accessible :employee_number, :joining_date, :first_name, :middle_name, :last_name,
:gender, :job_title, :employee_department_id, :qualification, :experience_detail,
:experience_year, :experience_month, :status_description, :date_of_birth, :marital_status,
:children_count, :father_name, :mother_name, :husband_name, :blood_group, :nationality_id,
:home_address_line1, :home_address_line2, :home_city, :home_state, :home_pin_code,
:office_address_line1, :office_address_line2, :office_city, :office_state, :office_pin_code,
:office_phone1, :office_phone2, :mobile_phone, :home_phone, :email, :fax, :user_id,
:reporting_manager_id, :employee_grade_id, :office_country_id,
:home_country_id, :employee_category, :employee_position_id
belongs_to :employee_department
has_many :counselor_supervisors
belongs_to :employee_position
def to_label
full_name = first_name + " " + last_name
end
end
EmployeeDepartment.rb
class EmployeeDepartment < ActiveRecord::Base
attr_accessible :code, :name
has_many :employees
has_many :employee_positions
has_many :counselor_supervisors
has_many :batch_leadership_supervisors
def to_label
name
end
end
CounselorSupervisor.rb
class CounselorSupervisor < ActiveRecord::Base
attr_accessible :employee_id, :employee_department_id, :employee_position_id
belongs_to :employee
belongs_to :employee_department
has_many :batch_counselor_supervisors
def to_label
employee.to_label
end
end
BatchCounselorSupervisor.rb
class BatchCounselorSupervisor < ActiveRecord::Base
attr_accessible :counselor_supervisor_id , :employee_department_id , :counselor_batch_id,
:batch_counselor_advisors_attributes
has_many :batch_counselor_advisors
belongs_to :counselor_supervisor
belongs_to :employee_department
belongs_to :counselor_batch
accepts_nested_attributes_for :batch_counselor_advisors
end
Employee_position.rb
class EmployeePosition < ActiveRecord::Base
attr_accessible :position_title, :employee_department_id
has_many :employees
belongs_to :employee_department
def to_label
position_title
end
end
batch_counselor_supervisors/new.html.erb (part of the form which related to my question)
<%= simple_form_for(#batch_counselor_supervisor) do |f| %>
<%= f.error_messages %>
<%= f.association :employee_department, as: :select %>
<%= f.input :counselor_supervisor_id , collection: EmployeeDepartment.all, as: :grouped_select, group_method: :counselor_supervisors %>
<% end %>
the dropdown list appears like this:
If I added an employee which belongs to the first department "Business Administration", the form will be displayed correctly like this:
Update: after adding label_method: :to_label, so my form became like this :
<%= simple_form_for(#batch_counselor_supervisor) do |f| %>
<%= f.error_messages %>
<%= f.association :employee_department, as: :select %>
<%= f.input :counselor_supervisor_id ,
collection: EmployeeDepartment.all, as: :grouped_select, group_method: :counselor_supervisors, label_method: :to_label %>
<% end %>
the employee name displayed correctly but still the department name not displayed correctly as the following image:
Is this SQLite3 issue ? and What can I do in order to solve this if it sqlite3 issue or not.

From what I see, you only have an issue with the labels not being displayed correctly. Could you try to explicitly set the method on your input:
label_method: :to_label
For more information have a look at https://github.com/plataformatec/simple_form and search for *label_method*

What are the actual relevant rows in your Employee table and your EmployeePosition table?
In your Employee table you happen to have these 2 columns;
employee_position_id
employee_position.
Since employee_position is also a table name, it's bad/reduntant model structure which might be confusing your include method of the query. It's possible that in your tables, the rows are fully filled out to complete the first query, but not for any of your other queries even though you think it is.

Possible to chain queries in Rails 3?

I have something like the following
class Group < ActiveRecord::Base
has_many :group_users
end
class GroupUser < ActiveRecord::Base
belongs_to :user, :group
end
class User < ActiveRecord::Base
has_many :group_users
end
The reason I'm not using has_many_through is because the group_user class has more information than just a link table, so I want to be able to access those values.
What I would like to do though is pass #groups to the page and loop through the group users but get at the user object as well
so
<% #groups.each do |group| %>
<%= group.group_user.user.name %>
<% end %>

Here is how I would do it:
User Model
class User < ActiveRecord::Base
has_many :memberships
has_many :groups, :through => :memberships
end
Group Model
class Group < ActiveRecord::Base
has_many :memberships
has_many :users, :through => :memberships
end
Membership Model
class Membership < ActiveRecord::Base
belongs_to :user
belongs_to :group
end
Controller
def show
#groups = Group.all
end
View
<% #groups.each do |group| %>
<% group.users.each do |user| %>
<%= user.name %>
<% end %>
<% end %>
There are probably a few ways to do it, but this should get you started.
Hope this helps!

If you want to access attributes from the GroupUser model, just do this:
<% #groups.each do |group| %>
<% group.group_users.each do |group_user| %>
<%= group_user.attribute_name %>
<%= group_user.user.name
<% end %>
<% end %>
To make this more efficient from the SQL side of things you can use eager loading:
Group.all(:includes => [:group_users => :user])
F

Show Name instead of ID in a HABTM relationship

Excuse me if I'm being too much of a beginner but none of the other related answers worker.
I want to show the category name that the links belong to instead of the id.
Here's the migration.
class CreateCategoriesLinks < ActiveRecord::Migration
def self.up
create_table :categories_links, :id => false do |t|
t.references :category
t.references :link
end
end
def self.down
drop_table :categories_links
end
end
The categories model
class Category < ActiveRecord::Base
has_and_belongs_to_many :links
end
The links model
class Link < ActiveRecord::Base
has_and_belongs_to_many :categories
end
And here's what's in the links controller under index and show
#categories = Category.find(:all, :order => 'name')
and here's what's in the index right now but, I've tried every permutation of this that I could find.
<%= link.category.name %>
If it put <%= link.category_ids %>, it'll show the ids.

Try:
<% link.categories.each do |cat| %>
<%= cat.name %><br>
<% end %>