CODEWITHSUNDEEP
ruby-on-railsruby
Edgars
Edgars

Reputation: 953

belongs_to and has_many association problems

I have two models User and Hobbie model. Hobbie has already 4 records like music, sports, books and other.

Then I have form where I can create User and there I can select from checkboxes those Hobbies at least 2.

User.rb

has_many: hobbies

Hobbie.rb 

belongs_to :user

Form:

 <%= form_for(@user,  :remote=>"true",:html => {:id=>"new_user","data-parsley-validate" => true,:multipart => true}, remote: true ,format: :json) do |f| %>
               ...

         <% @hobbies.each do |hobbie| %>
              <li>

                <%= check_box_tag 'hobbie_ids[]',hobbie.id%> <%= h hobbie.name %>                       
              </li>        
                 <%= f.submit %>
         <% end %>
     <% end %>

When I create user with hobbies like music and sports it saves without problems.

t= User.last
t.hobbies => "music", "sports"

Problem: When I go for second user and select hobbies like sports and books and save.

Then in console:

t.User.last
t.hobbies => "sports" and "books"

But for first User there is just "music" left.

I can't figure it out. Do I need to use other assocciation type to get this to work?

Thanks.

Upvotes: 2

Views: 196

Answers (1)

max
max

Reputation: 101811

A standard has_many : belongs_to relationship in rails will only allow a single user per hobby.

This is due to the fact that the relationship is defined by a single integer column (user_id) on the hobby table. The following image from the Rails Guides illustrates this relationship:

has_many relationship illustration

What you most likely are looking for is a has_and_belongs_to_many relationsship:

Image from Rails Guides

class User < ActiveRecord::Base
  has_and_belongs_to_many :hobbies
end

class Hobby < ActiveRecord::Base
  has_and_belongs_to_many :users
end

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

    create_table :hobbies do |t|
      t.string :name
      t.timestamps null: false
    end

    create_table :users_hobbies, id: false do |t|
      t.belongs_to :user, index: true
      t.belongs_to :hobby, index: true
    end
  end
end

The key difference here being that the relationship between hobby and user is stored in the users_hobbies join table.

Upvotes: 3

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