How to handle each iterator?

Question

I want to print the values taken from two different tables in the database in a table on the view page. I am not getting how to handle two each iterators as it is behaving abnormally i.e Printing a value several times. I am very much confused. Please help.

Here is my code

In the controller:

class ListController < ApplicationController

  def all
    @books = Book.all   
    @susers = SUser.all    
  end
end

In my view page

<tbody>                     
  <% @books.each do |b| %>
    <% if b.branch == "I.T" %>                                      
      <tr>
        <td><%= b.id %></td>
        <td><%= b.book_name %></td>
        <td><%= b.year %></td>
        <td><%= b.user_id %></td>    

        <% @susers.each do |s| %>                   
          <% if s.user_id == b.user_id %>
            <td><%= s.address %></td>
          <% else %>
            <td>Error..!!</td>
          <% end %>
        <% end %>                       
      </tr> 
    <% else %>
      <% puts "No any book of this branch" %>   
    <% end %>                                       
  <% end %>                                 
</tbody>

The output is displayed like this

The else part of the first if statement is repeating it self again and again. I dont know why it is happening?

There are 3 models in this project. 1. User - Made by devise 2. Book 3. SUser

One important thing: - Actually i made SUser model because i want to store user's personal details such as name, address, phone no. I dont want to touch devise model (User) so i made another model SUser which has one to one relation with devise model(User).

User model:

class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :token_authenticatable, :confirmable,
  # :lockable, :timeoutable and :omniauthable
  has_and_belongs_to_many :books
  has_one :s_user
  devise :database_authenticatable, :registerable,
       :recoverable, :rememberable, :trackable, :validatable

  # Setup accessible (or protected) attributes for your model
  attr_accessible :email, :password, :password_confirmation, :remember_me
  # attr_accessible :title, :body

end

Book Model:

class Book < ActiveRecord::Base
  # attr_accessible :title, :body
  has_and_belongs_to_many :users
  belongs_to :s_user, :class_name => "SUser"
  attr_accessible :id, :user_id, :book_name, :edition, :author, :branch, :publisher,      :year, :details 
end

SUser model:

class SUser < ActiveRecord::Base
  # attr_accessible :title, :body
  has_one :user
  has_many :books
  attr_accessible :user_id, :fullname, :email, :address, :details 
end

Migrations files:

class CreateBooks < ActiveRecord::Migration
  def change
    create_table :books do |t|
    t.integer "user_id", :limit =>5
    t.string "book_name", :limit => 50
    t.integer "edition", :limit => 5
    t.string "author", :limit => 30
    t.string "branch", :limit => 30
    t.string "publisher", :limit => 50
    t.integer "year", :limit => 10     
    t.text "details"
    t.timestamps
  end
  add_index :books, "user_id"
 end
end

SUser migration file

class CreateSUsers < ActiveRecord::Migration
 def change
  create_table :s_users do |t|
    t.integer "user_id", :limit => 5
    t.string "fullname", :limit => 25            
    t.string "email", :default => "", :null => false
    t.string "hashed_password", :limit => 40
    t.string "salt", :limit => 40
    t.string "address",:limit => 25
    t.text "details"
    t.timestamps
  end
  add_index :s_users, "user_id"
 end
end

I made many to many relationship between user and book since one user have many books and one book can be available to many users. So i made a simple join table for many to many association

class CreateBooksUsersJoin < ActiveRecord::Migration
 def up
   create_table :books_users, :id => false do |t|
     t.integer "book_id"
     t.integer "user_id"
   end
  add_index :books_users, ["book_id", "user_id"]
 end

 def down
  drop_table :book_users
 end
end

Lol.. I have pasted my whole code over here. Actually i am new to rails.. Please guide me if you find any other flaw to this code. Thanks

Answer 1

You can define relations between your models, I think one to many relation type is suitable for your situation:

class Book < ActiveRecord::Base
  belongs_to :suser, :class_name => "SUser"
end

class SUser < ActiveRecord::Base
  has_many :books
end

Then in your controller you can write like this:

class ListController < ApplicationController
  def all
   @books = Book.includes(:suser).all
  end
end

And finally your view will look like:

<tbody>                     
<% @books.each do |b| %>
  <% if b.branch == "I.T"%>                                       
  <tr>
    <td><%= b.id%></td>
    <td><%= b.book_name%></td>
    <td><%= b.year%></td>
    <td><%= b.user_id%></td>    
    <td><%= b.suser.try(:address) %></td>
  </tr>   
  <%else%>
    <% puts "No any book of this branch"%>  
  <%end%>                                     
<%end%>                                 
</tbody>

P.S.: it's normal that you have repeating of else block because you check for each user if book.suser_id == suser_id (but there is a one to many relation between books and susers, so book belongs to only one user, to few in case you have many to many relation)

Answer 2

class Book < ActiveRecord::Base
  belongs_to :suser
end

class SUser
  has_many :books
end

class ListController < ApplicationController
  def all
    @books = Book.includes(:susers).all
  end
end

<tbody>                     
<% @books.each do |b| %>
  <% if b.branch == "I.T"%>                                       
  <tr>
    <td><%= b.id%></td>
    <td><%= b.book_name%></td>
    <td><%= b.year%></td>
    <td><%= b.user_id%></td>    
    <td><%= b.suser.address %></td>
  </tr>   
  <%else%>
    <% puts "Branch has no books"%>  
  <%end%>                                     
<%end%>                                 
</tbody>

Finally you will need a foreign key for the relationship, something like:

script/generate migration add_user_id_to_books

migration syntax can be tricky so open up the migration file (in db/migrate) and make sure that it is doing something similar to add_column :books, user_id, integer