tedlayea / checkpoint-04

[ruby, checkpoint]

Checkpoint 04

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.

Only place your answer between the backticks provided for you throughout the checkpoint.

Ruby Basics & Enumerables

Question 1

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

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

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

require "pry"
Class Person
  def initialize (person)
     @person:person
  end
  def offer_rose(person)
    puts "Would you take this rose, #{@person}, in exchange for giving an old beggar woman shelter from the bitter cold?"
  end
end

binding.pry
# To call the method:
young_prince=Person.new("offer_rose")
young_prince.offer_rose

Question 2

Assume the following hash...

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

Using Ruby...

• Remove "Belle" from residents
• Add "Belle" to the guests array

town.delete([:residents][1])
town[:guests][0]="Belle"

Question 3

Assume you have an array of strings representing friends' names...

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

Using .each and string interpolation, print the following text to the Terminal...

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

friends.map |friend| do
  Puts "Belle is friends with #{friend}"
end

Ruby OOP

Question 4

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

• A name (String) 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 (Boolean) attribute
• If the instance's name is "Simba", set the king attribute to true

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

class Animal
  attr_accessor:name
  def initialize (name)
     @name:name
  end
  def greet
    puts "Hi my name is #{@name} and I am Animal."
  end

end
class Lion < Animal
  @@pack=[]
  def initialize (name)
     @name:name
     @@pack.push(@name)
  end
end

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

# ERD (Entity Relation Diagram) is a diagrammatic representation of the relationship
# between the major entities and feature in our application.
# E.g. A person can have many pet, so the relationship will be one to many.
# In reverse, many pet can belong to a single Person, but can`t belong to many person assuming Person as registered owner. So the relationship will be many to one.

Question 6

Describe what a schema is and how we represent a one-to-many relationship in a SQL database.

# Schema is used to define what columns the table will have. Such as column name, data type
# and any constraints if they have.
# We represent one-to-many relation using the keyword"has_many"

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...

abc= Person.new(name:abc,age: 53)
abc.save

OR
abc=Person.create(name:abc,age: 53)

Question 8

Assuming the Person class from the previous question, write Ruby code that will query for any person that is 15 years of age...

age_of_15=Person.find_by(age:15)

Question 9

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

get '/oh_hello'
  "Hello world"
end