Trying to make a form using nested attributes

Question

I\'m a beginner in rails, so I\'m quite stuck with the nested attributes.

Here is an overview of what I\'m looking for:

A rentalcar can create cars.(done)

Answer 1

I believe your relationships are a bit messed up, this is how I created new relations.

class AddRelevantModels < ActiveRecord::Migration
  def change
    create_table :car_rentals do |t|
      t.string      :name
      t.timestamps  null: false
    end

    create_table :cars do |t|
      t.string      :model
      t.string      :car_number
      t.belongs_to  :car_rental, index: true, foreign_key: true
      t.timestamps  null: false
    end

    create_table :clients do |t|
      t.string      :full_name
      t.integer     :age
      t.string      :email
      t.string      :phone_number
      t.timestamps  null: false
    end

    create_table :reservations do |t|
      t.belongs_to    :car, index: true, foreign_key: true
      t.belongs_to    :client, index: true, foreign_key: true
      t.datetime      :start_date
      t.datetime      :end_date
      t.timestamps    null: false
    end
  end
end

car_rental.rb

class CarRental < ActiveRecord::Base
  has_many :cars
end

car.rb

class Car < ActiveRecord::Base
  has_many :reservations
  has_many :clients, through: :reservations
end

reservation.rb

class Reservation < ActiveRecord::Base 
  belongs_to :client
  belongs_to :car

  accepts_nested_attributes_for :client
  accepts_nested_attributes_for :car
end

client.rb

class Client < ActiveRecord::Base
  has_many :reservations
  has_many :cars, through: :reservations
end

reservations_controller.rb

class ReservationsController < ApplicationController
  def new
    @reservation = Reservation.new
    @reservation.build_client
  end

  def create
    @reversation = Reservation.new(reservation_params)

    if @reversation.save
      render :show, id: @reservation
    else
      render :new
    end
  end

  private

  def reservation_params
    params.require(:reservation)
    .permit(
      :start_date, :end_date, client_attributes: [:full_name, :age, :email, :phone_number]
    )
  end
end

reservations/new.html.erb

Reservations
<%= form_for(@reservation) do |f| %>
  <%= f.label :start_date %>
  <%= f.text_field :start_date %>
  

  <%= f.label :end_date %>
  <%= f.text_field :end_date %>
  

  <%= f.fields_for :client do |client_field| %>
    <%= client_field.label :full_name %>
    <%= client_field.text_field :full_name %>
    
  
    <%= client_field.label :age %>
    <%= client_field.text_field :age %>
    
   
    <%= client_field.label :email %>
    <%= client_field.text_field :email %>
    

    <%= client_field.label :phone_number %>
    <%= client_field.text_field :phone_number %>
  <% end %>

  

  <%= f.submit %>
<% end %>

Now if you submit the form you can see in your database that the client is also saved for the reservation.

 Reservation.first.client
  Reservation Load (0.5ms)  SELECT  "reservations".* FROM "reservations"   ORDER BY "reservations"."id" ASC LIMIT 1
  Client Load (0.4ms)  SELECT  "clients".* FROM "clients"  WHERE "clients"."id" = $1 LIMIT 1  [["id", 1]]
 => #