In this article I am going explain nested resouces in rails . I hope you all familiar with REST in rails I am not going to discuss REST nature here.Here just consider we two resouces named as Projects and Tasks , here I am assuming that every task is related to certain Project and without project there is no task. So I will do make association has_many between Projects and Tasks .it will look like following

 class Project < ActiveRecord::Base  
  attr_accessible :name  
  has_many :tasks ,:dependent => :destroy  
 end  
 class Task < ActiveRecord::Base  
  attr_accessible :name  
  belongs_to :project  
 end  

generally our routes.rb file is like the following

 routes.rb  
 -----------------  
 resources :projects  
 resources:tasks  

so lets we modify the routes as following

  resources  :projects do   
    resources :tasks  
  end  

that’s it REST will do the magic for us . so now we need to concern about how to create task by following REST full routes new_task_path wont work here , it will rise an error , so we must take care while using routes here, do not worry I will tell how to do this creating new task with using the following line

 <%= link_to 'New Task', new_project_task_path(@project) %>  

it will open form for creating new task , it will look like this and I have done small changes that to create new task I have modified target file , please observe it

 <%= form_for([@project,@task]) do |f| %>  
  <div class="field">  
   <%= f.label :project_id %><br />  
   <%= f.text_field :project_id %>  
  </div>  
  <div class="field">  
   <%= f.label :name %><br />  
   <%= f.text_field :name %>  
  </div>  
  <div class="actions">  
   <%= f.submit %>  
  </div>  
 <% end %>  

and the tasks controller new action and create action are look like the following

 def new  
   @project = Project.find(params[:project_id])  
   @task = Task.new  
 end  
 <br/>  
 def create  
   @project = Project.find(params[:project_id])  
   @task = Task.new(params[:task])  
   respond_to do |format|  
    if @task.save  
     format.html { redirect_to project_path(@project), notice: 'task was successfully created.' }  
    end  
   end  
  end  

and we can write delete link as follows

 <%= link_to "Delete task", project_task_path(@project, @task), :confirm => "Are you sure you want to delete this task?", :method => :delete %>  
 and also you can edit task by using following path   
 <%= link_to 'Edit task', edit_project_task_path(@project,@task) %>  

I hope this will help you to give some idea nested routes with rails .I welcome your comments on this article so that i can improve further .thank you

Thanks Ratnakar V

About the Author

Ratnakar is a Software Engineer, Blogger from India.His articles mainly focus on Ruby on Rails Technology.

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Mongodb Installation.

.

Hi , in my previous article I posted how to work with mongoid with rails and some basics about mongodb Mongoid with Rails ,  Mongodb with Rails and here is installation steps of mongodb in ubuntu

Step 1 :

open terminal by typing shift+alt+T

Step 2 :

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv 7F0CEB10

Step 3 :

Create a file in the following directory ,at your terminal type the following

cd /etc/apt/sources.list.d then
touch 10gen.list

open the file by typing following command

sudo nano  10gen.list
then enter the following line 
deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen
 press enter and then ctrl+X  it will ask to save file then press Y

Step 4 :

Then we need to reload the repository by using the following command at your terminal

sudo apt-get update

Now its the time to install 10 gen packages (mongodb maintained by 10gen)

Step 4 :

sudo apt-get install mongodb-10gen

This will install all 10gen packages required for mongodb , when this is done at terminal you see the following line

Adding user `mongodb' to group `mongodb' ... 
Adding user mongodb to group mongodb 
Done.

Thats it you have successfully installed mongodb in your system . Then try start/ stop mongodb services by using the following commands

sudo service mongodb start
sudo service mongodb stop

Connect to mongodb by using the following command at terminal

mongo

it will connect to default database 'test' , you can see in terminal following lines

MongoDB shell version: 2.2.2 
connecting to: test 
Welcome to the MongoDB shell. 
For interactive help, type "help". 
For more comprehensive documentation, see 
 http://docs.mongodb.org/ 
Questions? Try the support group 
 http://groups.google.com/group/mongodb-user 

You can use mongodb GUI tools , the following link will guide you through several tools choose any one of them

http://www.mongodb.org/display/DOCS/Admin+UIs 

I hope this will give some sort of idea how to install mongodb ..I welcome your comments on this article thank you

Cheers,
Ratnakar

About the Author

Ratnakar is a Software Engineer, Blogger from India.His articles mainly focus on Ruby on Rails Technology.

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Hi, Every one , I feel that my posts are useful for you to get knowledge on Rails and please suggest me if you have any useful topics so that we will discuss more on those topics . here I am going to explain how Mongoid works with rails3 , here I explained some basics to get start with mongoid .
    as i have posted previously mongodb is so flexible and its document oreiented . We have sevaral ORM 's in the market we all know that ActiveRecord is one of the famous ORM for rails when we are dealing with relational databases . Now here we are dealing with ODM 's means Object Document Mapper . There are several ODM ' s are there few things i listed out here in conjuction with rails

  1.MongoMapper  
  2.Mongoid  
  3.Mongomatic  
  4.MongoODM  
  5.MongoModel  
  6.DriverAPILayer  

these are all ruby based ODM's Here i am going to create small application which will give some idea about how to use Mongoid

Step 1:

  install the mongoid gem by typing the following at your terminal  
   "gem install mongoid " or else you can add it your gem file  

Step2 : create a new rails application

 rails new mongoid_app  

Step3 : go to your mongoid_app

 cd monoid_app  

Step 4 : here I want to create two models Movie and Dancer and later i will associate both .
    First generate scaffold for movie model

 rails g scaffold Movie name:string   

which will create model , controller and veiws for movie model , in the same way create dancer model also

 rails g Dancer name:string  

then open your model and simply just include the following line in your model

 include Mongoid::Document  

follow the example below Ex :

 class Movie  
  include Mongoid::Document  
  field :name , type:String  
 end  

this will give ability to our class to act as a mongo document . Here we can see that our movie model contains only one field called name , if we want to add extra fields then no need of migrations here ,(oh sounds cool) simply add field name and type , once you enter the data and run the application it will add to database really how simple it is ! I will add one more field here

 class Movie  
  include Mongoid::Document  
  field :name , type:String  
  field :budget , type : Integer  
 end  

in the same way include Mongoid::Document to the Dancer model also .

 class Dancer  
  include Mongoid::Document  
  field :name , type:String  
 end  

now i will associate both models with has_many relation , just like the activerrecord relations we can add here also here I am going to establish Movie has_many dacers . See the following code snippet

 class Movie  
  include Mongoid::Document  
  field :name , type:String  
  field :budget , type : Integer  
 embeds_many :dancers  
 end  

and Dancer model is

 class Dancer  
  include Mongoid::Document  
  field :name , type:String  
  embedded_in :artist  
 end  

now we can query model simply by the following

 fetch Movie Model :  
  @movie = Movie.first  
 fetch movie related dancers  
  @dancers = @movie.dancers  

I hope this will help you to give some idea mongoid with rails .I welcome your comments on this article so that i can improve further .thank you Thanks Ratnakar V

About the Author

Ratnakar is a Software Engineer, Blogger from India.His articles mainly focus on Ruby on Rails Technology.

Reach Him :

Google+

Facebook

Twitter