rails scaffold from scratch
TRANSCRIPT
www.hackyale.com
< Intro to Rails />
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Building MVCr from scratch
< front end />
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MVC Recap
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hand-crafted,artisanal
rails code
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router
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ROUTER
the router looks at the incoming request and sends it to the right controller.
Example:
myapp.com/users/1/edit
goes to the users controller, edit action(and sends a ‘parameter’ for user_id=1 as )
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ROUTER
/users users#index list all users
/users/1 users#show show user with id 1
/users/new users#new make a new user
/users/1/edit users#edit edit user with id 1
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SAMPLE ROUTE
RedditDemo::Application.routes.draw do match 'users/' => 'users#index' root to: 'users#index'end
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controller
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CONTROLLER
The controller orchestrates the request.
It communicates with models to gather and manipulate data.
It then passes that data to the view.
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CONTROLLER ACTIONS
Controllers have multiple actions.
The standard ‘restful’ actions are:
indexshowcreateneweditupdatedestroy
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SAMPLE CONTROLLER
class UsersController < ActionController::Base def index @users = User.all endend
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views
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VIEWS
Views are templates for how your web pages look.
Variables created in the respective controller are used to insert relevant information into the template.
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VIEWS
Views use Embedded RuBy (ERB) to substitute data into the template.
<% ruby.code.no.output %>
<%= equal.sign.outputs.to.template %>
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SAMPLE VIEW
<% @users.each do |user| %> <%= user.name %><% end %>
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models
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MODELS
Models represent the nouns and data in your application.
They make sure stored data is valid, and perform calculations/analysis.
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DATABASES
•Store our model data (in rows), and define the attributes (columns).
•We manage changes in our database with migrations.
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MIGRATION
>> rails generate migration CreateUsers
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :first_name
t.string :last_name
t.string :netid
t.timestamps
end
end
end
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DATABASE
id first_name last_name netid
1
2
3
Adam Bray alb64
Vladimir The Bear vtb39
Charlie The Horse cth44
users
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DATABASE
id first_name last_name netid
1
2
3
Adam Bray alb64
Vladimir The Bear vtb39
Charlie The Horse cth44
users
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ADDING ANOTHER COLUMN
rails generate migration AddClassYearToUsers class_year:integer
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DATABASE
id first_name last_name netid class_year
1
2
3
Adam Bray alb64 1995
Vladimir The Bear vtb39 2015
Charlie The Horse cth44 2016
users
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SAMPLE MODEL
class User < ActiveRecord::Baseend
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group activity:add show page
for users
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YOU’LL NEED TO:
•create a route
•add a controller action
•add a view template
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TIPS
params hash:if you put symbols in your route they are available in controller
e.g. ‘users/:id’ gives you ‘params[:id]’ in controller
retrieving modelsuser.find(num) returns user with id == num
use link_to method to link from index
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group activity:add new user
form
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YOU’LL NEED TO
•add two new routes• use ‘resources’ route instead
•add two new actions, new, and create• new generates a form
• create takes form data and uses it to create user
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FORMS
<%= form_for(@user) do |f| %> <div class="field"> <%= f.label :first_name %><br /> <%= f.text_field :first_name %> </div> <div class="actions"> <%= f.submit %> </div><% end %>
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