dlin2102/checkpoint-04

[ruby, checkpoint]

Checkpoint 04

If you have not completed the survey yet, please do so by the end of the day!

Instructions

1. Fork this repo
2. Clone your fork
3. Fill in your answers by writing in the appropriate area or, for multiple-choice questions, placing an 'x' in the square brackets.
4. Add/Commit/Push your changes to Github.
5. Open a pull request.

For questions 1-4, you must test your code before filling in an answer. You can do this by creating and running your own app.rb file or using an online REPL (e.g., repl.it).

Note: Only place your answer between backticks. Don't modify the backticks, or the language specifier after them.

Ruby Basics & Enumerables

Question 1

Define a method called offer_rose, which should take one argument named person.

When called the method should puts "Would you take this rose, person, in exchange for giving an old beggar woman shelter from the bitter cold?"

Demonstrate calling the method, passing in "young prince" as the argument.

Write your code here...

def offer_rose("young prince")
  puts "Would you take this rose, #{young prince}, in exchange for giving an old beggar woman shelter from the bitter cold?"
end

Question 2

Assume the following hash...

town = {
  residents: ["Maurice", "Belle", "Gaston"],
  castle: {
    num_rooms: 47,
    residents: "Robby Benson",
    guests: []
  }
}

Using Ruby...

• Remove Belle from the town residents
• Add her to the list of guests in the castle.

Write your code here...

town[:residents].delete("Belle")
town[:guests]= "Belle"

Question 3

Assume you have an array of strings representing friend's names...

friends = ["Chip Potts", "Cogsworth", "Lumière", "Mrs. Potts"]

Using .each and string interpolation, puts the following text...

Belle is friends with Chip Potts
Belle is friends with Cogsworth
Belle is friends with Lumière
Belle is friends with Mrs. Potts

Write your code here...

friends.each do |friend|
  puts "Belle is friends with #{friend}"
end

Ruby OOP

Question 4

Create ruby classes for Animal and Lion. Each Animal should have...

• A name attribute
• A greet instance method
• The ability to "get" and "set" name

Create a new Animal instance with the name "Pumba".

Make the Lion inherit from the Animal class. The Lion class should have a pack class variable that holds references to each instance created.

Each lion should have...

• A king attribute which is a boolean
• If the instance's name is "Simba" make the king attribute true

Create a new lion instance with the name "Simba".

class Animal
  attr_accessor :name

  def initialize (name)
    @name = name
  end

  def greet(name)
    puts "Hello, my name is #{name}"
  end

end

Puma = Animal.new

class Lion < Animal
  attr_accessor :name
  @@pack = []

  def initialize (name, king)
    @name = name
    @king = king_or_not
    @@pack.push(self)
  end

  def king_or_not(name)
    if name == "Simba"
      puts "#{name} is king"
  end


end

Simba = Lion.new

SQL, Databases, and ActiveRecord

Question 5

Describe what an ERD is, and why we create them for applications. Also give an example what the attributes and relationships might be for the following entities (no need to draw an ERD)...

• Genie
• Lamp
• Person
• Pet

Your answer...

An ERD is a relational blueprint tool that lets us map out data and plan out our data structure. The lamp would be connected to the genie. The person would be connected to the lamp, the pet, and the genie. The genie would have a one to many relations to the person.

Question 6

Describe what a schema is, and how we represent a one-to-many relationship in a SQL database. If you need an example, you can use people and wishes models.

Your answer...

A schema defines the columns in a table. For each column, it defines the name, data type, and any constraints. We represent a one to many with a fork symbol or using the parent id in the children table. So one person would have many wishes. So the wishes table would have the person id.

Question 7

Consider a class Person that inherits from ActiveRecord::Base and has the following schema...

class Person < ActiveRecord::Base
end

CREATE TABLE persons(
  id SERIAL PRIMARY KEY,
  name VARCHAR NOT NULL,
  age INT NOT NULL
)

Write Ruby code that will create an instance of a person.

Your answer...

steve = Person.new(name: "steve", age:23)

Write Ruby code that will query for any person that is 15 years of age.

Your answer...

Person.find_by(age: 15)

Question 8

Write a route in Sinatra that will print "hello world" in the web browser at the following URL: http://localhost:4567/oh_hello

Your answer...

get '/oh_hello' do
  "Hello World"
end