Intro to Rails Flashcards

Question

ORM: Objects become ____ in those \_\_\_\_\_

Answer 1

Objects become **rows** in those **tables**

Answer 2

•**Classes** are singular and table is **pural**

Answer 3

•How can we save objects in a **DB**?

Answer 4

Object-relational mapping (ORM) is a technique (a.k.a. design pattern) of accessing a relational database from an object-oriented language (Java, for example)

Answer 5

•Rails has ActiveRecord to do this, and much more –Add, delete, find, modify, etc.

Answer 6

•Upside: stay within **Ruby** and **Rails**, no SQL

Answer 7

•XML **builder**

Answer 8

* Class **methods** perform **table-level** operations * Instance **methods** perform **row-level** operations

Answer 9

•ERb templates –Allows **embedding** of Ruby in a document –Somewhat violates **separation** of concerns

Answer 10

•ActionPack contains **methods** for **views** and **controllers**

Answer 11

**Manages** sessions

Answer 12

•Manages **caching**

Answer 13

Responsible for **routing**

Answer 14

CamelCase (also camel caps or medial capitals) is the practice of writing compound **words** or **phrases** such that each **word** or **abbreviation** begins with a **capital** letter.

Answer 15

•One major part of conventions is naming –In most applications, names are meaningless to the software –In Rails, names drive much of the functionality * Creating a model for a Person creates a database table people * Variables lowercase and underscores * Classes are CamelCased

Answer 16

•DB table names “look like” class names –Always plural * With lowercase and underscores * Class Student –DB table students –app/models/students.rb

Answer 17

•Controllers –StudentController –app/controllers/student\_controller.rb –http://…/student/list * Calls list method in student\_controller.rb * Subdirectories add to path –View templates in app/views/student –Layout templates app/views/layouts/application.html.erb and .xml

Answer 18

$ rails **new** demo create create README.rdoc create Rakefile … Your bundle is complete! Use `bundle show [gemname]` to see where a bundled gem is installed. Post-install message from rdoc: Depending on your version of ruby, you may need to install ruby rdoc/ri data: \<= 1.8.6 : unsupported = 1.8.7 : gem install rdoc-data; rdoc-data --install = 1.9.1 : gem install rdoc-data; rdoc-data --install \>= 1.9.2 : nothing to do! Yay!

Answer 19

•create config/routes.rb –Message à method mapping –See via “rake routes” •create config/application.rb –Timezone, locale, encodings, preloads, etc. * create config/environment.rb * create config/environments

Answer 20

* rails server –e development * create config/environments/development.rb –No **caching**, etc. * create config/environments/production.rb * create config/environments/test.rb •

Answer 21

* create config/locales * create config/locales/en.yml * create config/boot.rb * create config/database.yml –Which DB to **use** and how to **connect**

Answer 22

* create public/404.html * create public/422.html * create public/500.html * create public/favicon.ico * create public/index.html * create public/robots.txt

Answer 23

* create test/fixtures * create test/functional * create test/integration * create test/unit * create test/performance/browsing\_test.rb * create test/test\_helper.rb

Answer 24

•**app**/controllers: –application\_controller.rb •app/**helpers**: –application\_helper.rb * app/**mailers** * app/models * app/views/layouts: –**application**.html.erb

Answer 25

$ rails generate **scaffold** Student studentname:string studentid:integer **invoke** active\_record The name 'Student' is either already used in your application or reserved by Ruby on Rails. Please choose an alternative and run this generator again.

Answer 26

•A scaffold in Rails is a full **set of model**, **database** migration for that **model**, controller to manipulate it, **views** to view and manipulate the data, and a **test suite** for each of the above.

Answer 27

* :datetime * :timestamp * :time * :date * :binary * :boolean -------------------------- * :primary\_key * :string * :text (short strings) * :integer * :float * :decimal (fixed precision, currency)

Answer 28

$ rails new demo $ cd demo $ rails generate **scaffold** Student studentname:string studentid:integer

Answer 29

class CreateStudents \< **ActiveRecord**::**Migration** def change create\_table :students do |t| t. **string** :studentname t. **integer** :studentid **t**.timestamps null: false end end end

Answer 30

$ rails **new** Student create create README.rdoc create Rakefile create config.ru create .gitignore create Gemfile […]

Answer 31

$ rake db:migrate == CreateStudents: **migrating** ================================================= -- create\_table(:students) -\> 0.0014s == CreateStudents: migrated (0.0015s) ========================================

Answer 32

$ rails destroy **scaffold** Student

Answer 33

$ spring **stop** $ cd .. $ rm –rf college

Answer 34

students GET /students(.:format) students#index POST /students(.:format) students#create new\_student GET /students/new(.:format) students#new edit\_student GET /students/:id/edit(.:format) students#edit student GET /students/:id(.:format) students#show PUT /students/:id(.:format) students#update DELETE /students/:id(.:format) students#destroy

Answer 35

$ more app/models/student.rb class Student \< ActiveRecord::Base attr\_accessible :id, :name end

Answer 36

class StudentsController \< **ApplicationController** GET /students GET /students.json def index @students = Student.all respond\_to do |format| format. html # **index**.html.erb format. json { render json: @students } end end

Answer 37

GET /students/1 GET /students/1.json def show @student = Student.**find**(params[:id]) **respond\_to** do |format| format. html # **show**.html.erb format. json { render json: @student } end end •

Answer 38

GET /students/new GET /students/new.json def new @student = Student.**new** respond\_to do |format| format. html # new.html.erb format. json { render json: @student } end end

Answer 39

GET /students/1/edit def **edit** @student = Student.find(params[:id]) end automagically calls app/views/students/edit.html.erb

Answer 40

POST /students POST /students.json def create @student = Student.**new**(params[:student]) respond\_to do |format| if @student.**save** format. html { redirect\_to @student, notice: 'Student was successfully created.' } format. json { render json: @student, status: :created, location: @student } else format. html { render action: "new" } format. json { render json: @student.errors, status: :unprocessable\_entity } end end end

Answer 41

PUT /students/1 PUT /students/1.json def **update** @student = Student.find(params[:id]) respond\_to do |format| if @student.update\_attributes(params[:student]) format. html { redirect\_to @student, notice: 'Student was successfully updated.' } format. json { head :no\_content } else format. html { render action: "edit" } format. json { render json: @student.errors, status: :unprocessable\_entity } end end end

Answer 42

DELETE /students/1 DELETE /students/1.json def destroy @student = Student.find(params[:id]) @student.destroy respond\_to do |format| format. html { redirect\_to students\_url } format. json { head :no\_content } end end end

Answer 43

•Classes are **camel cased**, Rails turns them into **lower cased** and **underscored**

Answer 44

•Classes are camel cased, Rails turns them into lower cased and underscored –Class StudentEmployee creates a table student\_employees

Answer 45

•If there is a ClassScheduler controller –Creates app/controllers/class\_scheduler.rb

Answer 46

* app/helpers/class\_scheduler.rb * ERb templates in app/view/class\_scheduler

Answer 47

•If a **request** arrives for “admin/book”, **Rails** looks for a book\_controller.rb in app/controllers/admin

Answer 48

•id – default primary key –Can override, but still reference via “id

Answer 49

•x\_id – foreign key for a table named x

Answer 50

•created\_at, created\_on, updated\_at, updated\_on –\_at have a time