A Question about Model and Database?

rubyonrails-talk
1

hi i m new to rails i need to know the => which is the best way to create Database table in Rails?

  1. rails generate model User name:string email:string this will create a migration file with something like this
class CreateUsers < ActiveRecord::Migration
  def change
    create_table :users do |t|
      t.string :name # *see here name column is already made becoz we have passed a parameters*
      t.string :email # *same as above*

      t.timestamps
    end
  end
end

this is one method 2) rails generate model Page this will create a empty migration file something like this

class CreatePages < ActiveRecord::Migration
  def change
    create_table :users do |t|
      ===>> *now we can add here like **t.string "name"** to create column manually* ========>>>>>
t.timestamps
    end
  end
end

So which is the good way to do above things example 1 or example 2? Please tell. and if i have to write a drop_table method in migration, can i write in the way which i showed below class CreateSubjects < ActiveRecord::Migration def change create_table :subjects do |t| t.string “name”

  t.timestamps
end

end

def self.down drop_table :subjects end end So again same question which is the good way to do above things example 1 ( model with parameter ) or example 2 ( model without parameter )? Thanks for Taking Time to Read.

2

please help me

3

Rails is smart enough to determine if you want to create or drop a table if you have done the migration with change

def change

#code here

end

it only depends on how you write the commands

if you do

rake db:migrate

then it will create the db (if the code inside change is about it) and if you do

rake db:rollback

it will drop that table

in other case then

def up

#create table here

end

def down

#drop table here

end

take a look here

http://guides.rubyonrails.org/migrations.html

and then here

http://stackoverflow.com/questions/10365129/rails-migrations-self-up-and-self-down-versus-change

http://stackoverflow.com/questions/7600415/rails-3-generate-migration-no-up-or-down-method

there is a lot more on google

JavierQ

4

use def change

forget up and down def

cheers

Fahim Babar Patel

5

thanks for reply

6

It is entirely up to you, do whichever you prefer.

Colin