12:21 AM
Reinhart
Ruby is not Unidentified Programing Object, but it is Universal Programing Object
As we know that rails is built by MVC design. Let we understand MVC (Model-View-Controller) instantly.
- Model contains all information of operations or tasks that corresponding to process your database like CREATING, READING, DESTROYING, and UPDATING your database. Transaction Support and Store Procedure are created in Model too. But Transaction Object is in Controller.
- View, it's all about display of your information or output of process. Your webdesign, information that want be displayed to realworld or user and output of data process are managed in View files.
- Controller is brain of everything. Like the name, it controlls all process and also filter for all information of input or output. example before data displaying to realworld/ your user, it should pass controller first .
So where is Active Record in Ruby on Rails? it is in model. Active Record is Ruby Library that allows your Ruby programs to transmit data and commands to and from various data stores,whic are usually relational database. If you dont have Active Record, dont go away. Calm down and type this gem install activerecord to your ruby cmd. Let's implement it.
Create a Record
email = Email.new
email.username = "teapoci"
email.password = "myfav_tea"
email.customer_name ="Ariand Handsome"
email.customer_country = "Indonesia"
email.save
The generated SQL would be
INSERT INTO emails ('username', 'password', 'customer_name') VALUES ('teapoci', 'myfav_tea', 'Ariand Handsome')
Reading a Record
all_email = Email.find(:all)
first_email = Email.find(:first)
email_by_id = Email.find(10)
The generated SQL would be
SELECT * FROM emails;
SELECT * FROM emails LIMIT 1;
SELECT * FROM emails WHERE id = 10;
How to use :conditions
Email.find(:all, :conditions => ["customer_country = ?", "Indonesia"] )
Email.find(:all, :conditions => [:customer_country => "Indonesia" )
Email.find(:all, :conditions => "customer_country => 'Indonesia' "
The generated SQL would be
SELECT * FROM Emails WHERE customer_country = 'Indonesia'
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Email.find(:all, :conditions => ["customer_name LIKE ? AND customer_country != ?", "%ar%", "Indonesia"] )
The generated SQL would be
SELECT * FROM emails WHERE customer_country LIKE '%ar%' AND customer_country NOT IN ('Indonesia');
How to use :include
:include is like join table in SQL, it will look like nested hash of ruby in its script.
class Customer < ActiveRecord::Base
has_many :invoices
end
class Invoice < ActiveRecord::Base
belongs_to :payment
end
class Payment < ActiveRecord::Base
belongs_to :processor
end
class Processor < ActiveRecord::Base
end
Customer.find(:all. :include => { :invoices => {:payments => {:processor = > {} } } }, :conditions => ["processor.name != ?", "paypal"])
The generated SQL would be
SELECT * FROM customers
LEFT OUTER JOIN invoices ON customer.id = invoices.customer_id
LEFT OUTER JOIN payments ON invoices.payments_id = payments.id
LEFT OUTER JOIN processors ON payments.processor_id = processor.id
WHERE processors.name NOT IN ('paypal');
How to use :order
Costumer.find(:all, :order => "created_on DESC, last_name, first_name")
The generated SQL would be
SELECT * FROM customers ORDER BY created_on DESC, last_name, first_name
How to use :select
Costumer.find(:all, :select => "customers.last_name, 'family name' " )
The generated SQL would be
SELECT last_name AS 'family name' FROM customers;
How to use :group
Costumer.find(:all, :group => "state" )
The generated SQL would be
SELECT * FROM customers GROUP BY state;
How to use :joins
Costumer.find(:all, :joins => "LEFT JOIN invoices ON customers.id = invoices.customer" )
The generated SQL would be
SELECT * FROM customers LEFT JOIN invoices ON customers.id = invoices.customer_id
How to use :from
Costumer.find(:all, :group => "state" )
The generated SQL would be
SELECT * FROM customers GROUP BY state;
to be continued....
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