Object Relations Code Challenge - Articles

For this assignment, you will be working with a Magazine domain.

We have three models: Author, Article, and Magazine.

For our purposes, an Author has many Articles, a Magazine has many Articles, and Articles belong to both Author and Magazine.

Author - Magazine is a many to many relationship.

Note: You should draw your domain on paper or on a whiteboard before you start coding. Remember to identify a single source of truth for your data.

Topics

• Classes and Instances
• Class and Instance Methods
• Variable Scope
• Object Relationships
• Arrays and Array Methods

Instructions

To get started, run bundle install while inside of this directory.

Build out all of the methods listed in the deliverables. The methods are listed in a suggested order, but you can feel free to tackle the ones you think are easiest. Be careful: some of the later methods rely on earlier ones.

Remember! This code challenge does not have tests. You cannot run rspec and you cannot run learn. You'll need to create your own sample instances so that you can try out your code on your own. Make sure your associations and methods work in the console before submitting.

We've provided you with a tool that you can use to test your code. To use it, run ruby tools/console.rb from the command line. This will start a pry session with your classes defined. You can test out the methods that you write here. You can add code to the tools/console.rb file to define variables and create sample instances of your objects.

Writing error-free code is more important than completing all of the deliverables listed - prioritize writing methods that work over writing more methods that don't work. You should test your code in the console as you write.

Similarly, messy code that works is better than clean code that doesn't. First, prioritize getting things working. Then, if there is time at the end, refactor your code to adhere to best practices. Examples of best practices might be to use higher-level array methods such as map, select, and find when appropriate in place of each, or, when you encounter duplicated logic, to extract it into a shared helper method.

Before you submit! Save and run your code to verify that it works as you expect. If you have any methods that are not working yet, feel free to leave comments describing your progress.

Deliverables

Write the following methods in the classes in the files provided. Feel free to build out any helper methods if needed.

Deliverables use the notation # for instance methods, and . for class methods.

Some of the methods listed are provided to you in the starter code. You should check that they work correctly, and that you understand them.

Initializers, Readers, and Writers

Author

• Author#initialize(name)
  • An author is initialized with a name, as a string.
  • A name cannot be changed after it is initialized.
• Author#name
  • Returns the name of the author

Magazine

• Magazine#initialize(name, category)
  • A magazine is initialized with a name as a string and a category as a string
  • The name and category of the magazine can be changed after being initialized.
• Magazine#name
  • Returns the name of this magazine
• Magazine#category
  • Returns the category of this magazine
• Magazine.all
  • Returns an array of all Magazine instances

Article

• Article#initialize(author, magazine, title)
  • An article is initialized with an author as an Author object, a magazine as a Magazine object, and title as a string.
  • An article cannot change its author, magazine, or title after it is has been initialized.
• Article#title
  • Returns the title for that given article
• Article.all
  • Returns an array of all Article instances

Object Relationship Methods

Article

• Article#author
  • Returns the author for that given article
• Article#magazine
  • Returns the magazine for that given article

Author

• Author#articles
  • Returns an array of Article instances the author has written
• Author#magazines
  • Returns a unique array of Magazine instances for which the author has contributed to

Magazine

• Magazine#contributors
  • Returns an array of Author instances who have written for this magazine

Associations and Aggregate Methods

Author

• Author#add_article(magazine, title)
  • Given a magazine (as Magazine instance) and a title (as a string), creates a new Article instance and associates it with that author and that magazine.
• Author#topic_areas
  • Returns a unique array of strings with the categories of the magazines the author has contributed to

Magazine

• Magazine.find_by_name(name)
  • Given a string of magazine's name, this method returns the first magazine object that matches
• Magazine#article_titles
  • Returns an array strings of the titles of all articles written for that magazine
• Magazine#contributing_authors
  • Returns an array of authors who have written more than 2 articles for the magazine

Rubric

You can find the rubric for this assessment here.