fh-homework-08

What is an Object? Please write your answer below.

An object is an instance of a class which allows you to define methods on it in order to get information or perform an action. Everything in Ruby is considered an object.
What is a Class? Please write your answer below.

A class represents a blueprint in which objects can be created from. It consists of a group of method definitions.
What's the difference between a class and module?

You can instantiate objects from a class but not from a module. Modules are used to extend the functionality of a class
What does the self mean in the Ruby language? Please write your answer below.

It refers to the default or current object when called on in different contexts. There is only one current object or self depending on what context it is in.
What is a block as defined in the Ruby language?

A block is a chunk of code enclosed either in a do...end clause or within brackets that you can invoke from methods. Blocks can be invoked inside methods using a yield statement.

Given the following: hash = { a: 1, b: 2, c: 3, e: 4, f: 5, g: 6, h: 7, i: 8, j: 9, k: 0 } Please answer the following questions:

How would I get the value of 'f'? Please write your answer below.

hash[f]
How would I add the key, 'l', with a value of 11 to the 'hash'? Please write your answer below.

hash[l] = 11
Write a method, sum_hash_values, which takes all the values of a hash produces a total. Please write your answer below.

def sum_hash_values( some_hash ) sum = 0 some_hash.values.each do |value| sum += value end sum end
Write a method, sum_hash_odd_values, which takes all of the odd values of a hash produces a total. Please write your answer below.

def sum_hash_odd_values( some_hash ) sum = 0 some_hash.values.each do |value| sum += value if value % 2 == 1 end sum end

Note: Please don't use any Ruby Standard library methods.

What's the difference between a Hash vs Array in the Ruby language? Write your answer below.

A Hash is a data structure that is a collection of key/value pairs
whereas an Array is an ordered collection of any objects.

The elements of a Hash are indexed through arbitrary keys of any type
whereas an array is done via integers.

Write a method to determine whether not a string is a palindrome using recursion?

def is_palindrome?( some_string ) _palindrome?( some_string, 0, some_string.length - 1 ) end

def _palindrome?( some_string, head_index, tail_index ) return if head_index == tail_index || head_index > tail_index

if some_string[head_index] == some_string[tail_index] head_index += 1 tail_index -= 1
_palindrome?( some_string, head_index, tail_index ) else false end end

is_palindrome( "bob" ) => true

is_palindrome( "frank" ) => false

is_palindrome( "pop" ) => true

is_palindrome( "xxxx yyyy xxxx" ) => true

Note: Please don't use any Ruby Standard library methods. Your solution should not be using map, each, for, while, and so on.
Given an array write a method to compute the length of an array using recursion.

def length( array , count=0) if array[count].nil? count else count += 1 length( array, count ) end end

Note: Please don't use any Ruby Standard library methods. Your solution should not be using map, each, for, while, and so on.
Given an array write a method to compute the length of an array using iteration.

def length( array )
  count = 0
  while ! array[count].nil?
    count += 1
  end
  count
end


Note: Please don't use any Ruby Standard library methods.

computes the power of number with a given exponent using recursion

def power(number, exponent) if exponent == 0 1 else number * power(number, exponent-1) end end

Note: Please don't use any Ruby Standard library methods. Your solution should not be using map, each, for, while, and so on.
Consider the following two methods:
```
def times_four(arg1);
 puts arg1 * 4;
end
```
```
def multiply(arg1, arg2);
  puts arg1 * arg2;
end
```
What will be the result of each of the following lines of code:

times_four 5 => please write your answer here times_four(5) => 20 times_four (5) => 20 multiply 1, 2 => 2 multiply(1, 2) => 2 multiply (1, 2) => syntax error
What is the convention for methods which end with a question mark? e.g. #all?, #kind_of?, directory?

a) They should always require arguments.

b) They should always return a boolean value.

c) They should always report a value of the object they're being called on.

For the string class, what's the difference between "#slice" and "#slice!"?

a) None, "#slice" is just an alias for "@slice!".

b) There is no "#slice!" method in Ruby on Rails.

c) "#slice" returns a new object, "#slice!" destructively updates - mutates - the object's value.

Given the Ruby expression a, b = b, a where a = 5 and b = 6. What's the value of 'a' and 'b' after the expression is executed?

a) a = 5, b = 6

b) a = 6, b = 5

c) a = 6, b = 6

Git Core

What are the steps (i.e. commands) to initialize a local Git repository? Please write your answer below.

cd into root directory of of application git init

What's the command to stage a file using Git? Please write your answer below.

git add <file_name>

What are the necessary commands to setup a local repository so that one can push to Github.com? Please write your answer below.

cd into root directory of application git init git add . git commit -am “Initial commit” login to github.com click Add New Repository and give it name copy/paste instructions on Github to set up existing repository

What does git checkout branch-name do? Please write your answer below.

This creates a new branch separate from the master branch where
someone can develop code in isolation. For example a team can use a
branch dedicated for a specific feature or workflow.

What does git checkout -b branch-name do? Please write your answer below.

This creates a new branch and switches to it immediately

What does git branch -D branch-name do? Please write your answer below.

This is an alias for git branch --delete --force, which removes a branch
regardless of its merge status

What does git merge branch-name do where branch-name is a sub branch of master? Please explain your answer below.

This merges the code from the sub branch into the master branch meaning
any revisions/additions from the sub branch are applied to the master

RSpec Core

What is TDD? TDD stands for test driven development. It is a methodology where emphasis is placed heavily on writing out test/specifications during development to ensure code is working properly. The general concept involves writing the test out, writing enough code to make it fail, rewriting it enough to make it pass, and then refactoring the code. This is commonly known as the red, green, refactor cycle.
What is RSpec? Please write your answer below?

RSpec is a Ruby and Ruby on Rails testing framework that focuses
on providing libraries for use in TDD.

Given the following Spec

```
describe Person do

  it 'should be valid' do
    person = Person.new( 'John', 'Doe')

    expect( person ).to_not be_nil
  end

end
```

Write the implementation below which will make this test pass.

class Person def initialize(first_name, last_name) end end

Note:  It may be better to run locally on your system for correctness?

Continuing with the previous spec write an example for testing a method full_name.

describe Person do

it '.full_name' do person = Person.new( 'John', 'Doe')

expect( person.full_name ).to eq('John Doe')

end end

Note:  If you created a person with the first name of `John` and the last name of
   `Doe`, then the `full_name` should generate `John Doe`.

Write the implementation code which passes the example we created in (29). Please write your answer below.

class Person def initialize(first_name, last_name) @first_name = first_name @last_name = last_name end

def full_name @first_name + " " + @last_name end end

Note:  If you created a person with the first name of `John` and the last name of
       `Doe`, then the `full_name` should generate `John Doe`.

Continuing with the previous spec write an example for testing a method reversed_full_name.

describe Person do

it '.reversed_full_name' do person = Person.new( 'John', 'Doe') full_name = person.full_name

expect( person.reversed_full_name ).to eq('Doe, John')

end end

Note:  If you created a person with the first name of `John` and the last name of
       `Doe`, then the `reversed_full_name` should generate `Doe, John`.

Write the implementation code which passes the example we created in (31). Please write your answer below.

class Person def initialize(first_name, last_name) @first_name = first_name @last_name = last_name end

def full_name @first_name + " " + @last_name end

def reversed_full_name @last_name + ", " + @first_name end end

Note: If you created a person with the first name of `John` and the last name of `Doe`, then the `reversed_full_name` should generate `Doe, John`.

Write the example and implementation code which passes the following examples.

```
describe Person do

  it '#first_name' do
    person = Person.new( 'John', 'Doe')

    expect( person.first_name ).to eq(‘John’)
  end

  it '#last_name' do
    person = Person.new( 'John', 'Doe')

    expect( person.last_name ).to eq(‘Doe’)
  end

end

class Person

attr_reader :first_name, :last_name def initialize(first_name, last_name) @first_name = first_name @last_name = last_name end

def full_name @first_name + " " + @last_name end

def reversed_full_name @last_name + ", " + @first_name end

end

Add a middle_name method to our Person class. Rewrite all the examples using the information from the above.

describe Person do

it '#initialize' do person = Person.new( 'John', 'Middle', 'Doe')

expect( person ).to_not be_nil

end

it '.full_name' do person = Person.new( 'John', 'Middle', 'Doe')

expect( person.full_name ).to eq('John Middle Doe')

end

it '.reversed_full_name' do person = Person.new( 'John', 'Middle', 'Doe') full_name = person.full_name

expect( person.reversed_full_name ).to eq('Doe, John Middle')

end

it '#first_name' do person = Person.new( 'John', 'Middle', 'Doe')

expect( person.first_name ).to eq('John')

end

it '#last_name' do person = Person.new( 'John', 'Middle', 'Doe')

expect( person.last_name ).to eq('Doe')

end

it '#middle_name' do person = Person.new( 'John', 'Middle', 'Doe')

expect( person.middle_name ).to eq('Middle')

end

Rails Core

Please explain M in model view controller (MVC) within the Ruby on Rails Framework? For example, what's the role of the model. Write your answer below in your own words.

The model contains the data and business logic of the MVC framework.  It
allows you to get the necessary data for displaying a particular output and

is stored in a database. The model can represent an arbitrary entity.

Please explain V in model view controller (MVC) within the Ruby on Rails Framework? For example, what's the role of the view. Write your answer below in your own words.

The view in the MVC framework contains all the code for outputting
what is shown in the browser.  In Ruby on Rails, the view can use a
combination of HTML and ERB template files to display content in the
browser.

Please explain C in model view controller (MVC) within the Ruby on Rails Framework? For example, what's the role of the controller. Write your answer below in your own words.

The controller is like the middleman between the model and view layers
of the MVC framework.  Its job is to acquire data from the model layer and
store it as instance variables which could then be passed into views. It
also contains all the actions used in the REST api (create, read, update
, destroy, etc. )

Use the Rails generator to produce a model called Actor which has the following fields:
- first_name - string
- middle_name - string
- last_name - string
Please write the command below.

rails generate model Actor first_name:string middle_name:string last_name:string

Implement the Actor class using Ruby. Write your answer below.

class CreateActors < ActiveRecord::Migration[5.1] def change create_table :actors do |t| t.string :first_name t.string :middle_name t.string :last_name

  t.timestamps
end

end end

Use the Rails generator to produce a model called Movie which has the following fields:
- actor_id - integer
- name - string
- release_on - date

Please write the command below.

rails generate actor_id:integer name:string release_on:date

Implement the Movie class using Ruby. Write your answer below.

class CreateMovies < ActiveRecord::Migration[5.1] def change create_table :movies do |t| t.integer :actor_id t.string :name t.date :release_on

  t.timestamps
end

end end

Use the Rails generator to produce a model called Filmography which has the following fields:
- actor_id - integer
- movie_id - integer
Note: This is our join model which we'll be able to associate a given actor to a movie.

rails generate model Filmography actor:references movie:references

Implement the Filmography class using Ruby. Write your answer below.

class CreateFilmographies < ActiveRecord::Migration[5.1] def change create_table :filmographies |t| t.integer :actor_id t.integer :movie_id

  t.timestamps
end

end end

Update the Actor model with the proper associations for accessing its' filmographies and movies. Write the updated model below.

class Actor < ApplicationRecord has_many :filmographies has_many :movies, through: :filmographies end

Update the Movie model with the proper associations for accessing its' filmographies and actors. Write the updated model below.

class Movie < ApplicationRecord has_many :filmographies has_many :actors, through: :filmographies end

Using the information from (43) - (45), write a Rails query which would give one all the movies for a given Actor. Please write your answer below.

@actor = Actor.find(params[:id]) @movies = @actor.filmographies.movies

Using the information from (43) - (45), write a Rails query which would give one all the actors which starred in a given Movie. Please write your answer below.

@movie = Movie.find(params[:id]) @actors = @movie.filmographies.actors

garyravago/fh-homework-08

fh-homework-08