RoR 101: Session 2

Building Web Apps with Rails

II

Try Ruby!
Http://tryruby.org

Stop when you see
"summary 4" or stuff
about file operations.

Skip to challenge on
Classes.

Scaffold
rails generate scaffold Station name:string
description:text url:string

Scaffold
rails generate scaffold Station name:string
description:text url:string

● Model
● View

● Controller

● Database Migration

Anatomy of a Rails App

Models, Views, & Controllers

Migrations Files

CRUD actions in the controller

●
Create – new, create

● Read – index, show

● Update – edit, update

●
Destroy - destroy

Session 2
● Rails Console
●
ActiveRecord Queries

● Views
●
Embedded Ruby Syntax
● Layouts

● Helper Methods

Controllers and Models

Models Controllers
DB


Models Controllers
DB

In stations_controller.rb (index):

@stations = Station.all


Models Controllers
DB

In stations_controller.rb (show):

@stations = Station.find(params[:id])


Models Controllers
DB

ActiveRecord::Base
Maps station model to stations table in database

The Rails Console

1. Open the terminal
2. Navigate to the 'firstfm' directory
3. Run the commands:
rails console

The Rails Console

rails console

Task!
Recreate the first line of the show action.

1. Create a hash with the key :id
2. Pass it into Station.find()

Go to
guides.rubyonrails.org/active_record_querying.html

The Rails Console

Recreate the first line of the show action.

1. Create a hash with the key :id
2. Pass it into Station.find()

Try out other AR methods:

guides.rubyonrails.org/active_record_querying.html

apidock.com/rails/ActiveRecord/Base

Views

Models Controllers
DB

@station = Station.find(params[:id])

Views

Views

Models Controllers
DB

@station = Station.find(params[:id])

Views

Views

Models Controllers
DB

respond_to do |format|
format.html # index.html.erb
format.json {render json: @stations }
end

View files match
action names

Where are
Create, update & destroy?

These are .erb,
embedded ruby files

index.html.erb:
...

<% @stations.each do |station| %>

#loop stuff

<% end %>

... <% %>
for code

show.html.erb:
…

 Name:
 <%= @station.name %>


 Description:
 <%= @station.description %>


 Url:
 <%= @station.url %>
 <%= %>
... for printing

show.html.erb:

<%= link_to 'Edit',
edit_station_path(@station) %>
|
<%= link_to 'Back', stations_path %>

What's this?

show.html.erb:

<%= link_to 'Edit',
edit_station_path(@station) %>
|
<%= link_to 'Back', stations_path %>

These are both view helpers.

View Helpers & Being DRY

Don't
Repeat
Yourself


View Helpers:

Methods we can call
in our views to write
less code / markup!


Rails Provides Us With Helpers:

● Links
● Forms

● Images

● And even more!

Layouts

Layout files are
found here

<!DOCTYPE html>
<html>
<head>
<title>Firstfm</title>
<%= stylesheet_link_tag "application" %>
<%= javascript_include_tag "application"
%>
<%= csrf_meta_tags %>
</head>
<body>

<%= yield %> The default layout
template.
</body>
</html>

<!DOCTYPE html>
<html>
<head>
%>
</head>
<body>
This is where our
<%= yield %> templates
are rendered
</body>
</html>

<!DOCTYPE html>
<html>
<head>
%>
</head>
<body>

<%= yield %> This helpers include
Our default js / css
</body>
</html>

Task: Display a logo image on each
page !

1. Find and download an image to use as
a logo

2. Put it in 'firstfm/public/assets/'

3. Display it with the 'image_tag' helper

Search for 'image_tag' on
http://apidock.com/rails for reference!

Web Browser
How does it
all fit together?

Rails
Routing System

Views

Models
DB Controllers

RoR 101: Session 2

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