Chapter 2

Question 1

create new rails app(all of its directories generated)

Answer 1

cd workspace
rails 4.2.2 new toy_app
cd toy_app

Question 2

$ bundle install –without production

Answer 2

flag prevents local installation of any production gems

Question 3

what must you do after you made changes to the gem file

Answer 3

run bundle install

Question 4

put rails app under version control

Answer 4

git init
git add -A
git commit -m “Initialize repository”

Question 5

pushing rails app after putting app under version control:

Answer 5

git remote add origin https://github.com/saweel/toy_app.git
git push -u origin master
(must create repository manually in github and then push it into it (thats what she said))

Question 6

typical first step when making a web application:

Answer 6

create data model, represenation of the structures needed by out application. in toy app, microblog, with only users and short posts. model for users and then model for microposts

Question 7

data model for a user

Answer 7

interger identifier (id), name (string), email (string)

Question 8

model for micropost

Answer 8

id (integer) and content text (string), we want to associate each post with a user, so we need user_id (integer) for the post

Question 9

user resource:

Answer 9

allow us to think users as objects that can be created, read, updated, and deleted through the web via the HTTP protocol. generage it using scaffold

Question 10

use scaffold command to generate a resource (user) with parameters for attributed: name and email of type string. why dont you need to include id?

Answer 10

$ rails generate scaffold User name:string email:string. no need to include parameter for id; it is created automatically by rails for use as the primary key in the database

Question 11

command to migrate database using Rake

Answer 11

$ bundle exec rake db:migrate. simply update the database with our new user data model. bundle exec to make sure rake corresponds to our gemfile version.

Question 12

rails s

Answer 12

shorcut for rails server

Question 13

make utility

Answer 13

in unix, building executable programs from source codes. commonly used to compile code

Question 14

rake

Answer 14

rails uses rake extensively especially in developing database-backed web applications. rake db:migrate most common.

Question 15

(root URL)/users

Answer 15

page to list all users (index)

Question 16

/users/1

Answer 16

page to show user with id 1 (show)

Question 17

/users/new

Answer 17

page to make a new user (new)

Question 18

/users/1/edit

Answer 18

page to edit user with id 1 (edit)

Question 19

heroku create

Answer 19

create subdomain name for us.

Question 20

why is show and update action correspond to the same url

Answer 20

difference is the http request method they respond to.

Question 21

what is REST?

Answer 21

architectural style for developing distributed, networked systems and software applications such as web applications.

Question 22

how does REST model users and microposts?

Answer 22

application components are modeled as resources that can be created, read, updated, and deleted - operations both to the CRUD of relational database and to HTTP request methods:

Question 23

HTTP request methods:

Answer 23

POST, GET, PATCH DELETE (learn more later on)

Question 24

@users = User.all

Answer 24

list all users from User object in model database and place them in variable

Question 25

mvc model summary to go to /users: (long answer 8 steps)

Answer 25

1. brower issues request for /users URL
2. Rails routes /users to index action in Users controller
3. index action asks User model to get all users
4. User model pulls users from database
5. User returns list of users to controller
6. stores in @users variable, which is passed to the index view.
7. the view uses embedded Ruby to render the page as HTML
8. controller passes the HTML back to the browser

Question 26

mvc model of /users in more detail (long answer)

Answer 26

1. request issued from browser (typing the url).
2. sent to rails router which determines the controller action based on URL.
3. action has @users = User.all
4. which asks User model to get all users.
5. stores users in @users.
6. controller calls the html.erb view and iterates through @users and otputs HTML code
7. view converts to HTML.
8. returned by the controller to the browser for display.

Question 27

how URL to route knows which action to perform?

Answer 27

in config/routes.rb, we create controller action pair with URL. example: root ‘users#index’.

Question 28

weaknesses of User resource

Answer 28

• no data validations(email can be wrong)
• no authentication (cannot login or logout and no way to prevent user from perfoaming any operation)
• no style or layout
• no real understanding
• no static pages (such as home or about)
• no user passwords
• no user images
• no security
• no following or followed, and more

Question 29

generate scaffold for Micropost

Answer 29

$ rails generate scaffold Micropost content: text user_id:integer

Question 30

after generating a new resource using scaffold, what do we have to do?

Answer 30

must run bundle exec rake db:migrate to update the database

Question 31

resources :microposts in route -

Answer 31

maps micropost URLs to actions in the Micropost controller

Question 32

constraint micropost text field to 140 characters(same as twitter)

Answer 32

app/models/micropost.rb

add:
validates :content, length: { maximum: 140 }

Question 33

write code to show a user has many microposts

Answer 33

has_many :microposts

app/models/user.rb

Question 34

code to show a micropost belongs to a user

Answer 34

app/models/micropost.rb

belongs_to :user

Question 35

$ rails console

Answer 35

useful tool for interacting with rails applications

Question 36

first_user = User.first (c)

Answer 36

store first user in variable

Question 37

first_user.microposts (c)

Answer 37

see all posts of user

Question 38

micropost = first_user.microposts.first

Answer 38

see first post of user

Question 39

micropost.user

Answer 39

see user info

Question 40

what do we gain from inheriting from ActiveRecord::Base

Answer 40

model objects gain the ability to communicate with the database, treat the database columns as Ruby attributes, and so on.

Question 41

user and micropost controller inheritance tree:

Answer 41

UserController

Question 42

inheriting from ActionController::Base provides what abilties?

Answer 42

manipulate model objects, filter inbound HTTP requests, and render views as HTML.

Question 43

to get heroku database to work:

Answer 43

$ heroku run rake db:migrate

Question 44

strength of this chapter:

Answer 44

high level overview of rails

• intro to MVC
• first taste of REST architecture
• beginning data modeling
• a live, database backed web application in production

Question 45

what is scaffolding

Answer 45

automatically creates code to model data and interact with it through the web