You're going to be implementing a Music Library domain composed of 3 main models, Song
, Artist
, and Genre
that will relate to each other and collaborate heavily. Additionally, you're going to be extracting some common functionality of those models into a module, Concerns::Findable
and mixing that module into those classes. You'll then build a collaborating object, MusicImporter
, that can parse a directory of MP3 files and use the filenames to create instances of Song
, Artist
, and Genre
. Finally, you'll build a CLI in bin/musiclibrary
that is powered by a MusicLibraryController
to provide a simple CLI that lets a user browse the library of MP3s imported by song, artist, and genre.
This is a complex lab with many parts, go slow, try to understand what you're trying to build holistically before starting. Read this entire README before jumping in. As you go from spec to spec, we recommend doing them in numbered order.
A quick note on the placement of Modules. It's Ruby convention to put all Modules in a concerns
folder and to be namespaced like this Concerns::ModuleName
.
The first thing to do is get the basics of the main models working. Each model has almost the exact same basic requirements, so once you make 001_song_basics_spec.rb
pass by building the Song
class, the Artist
and Genre
basic specs will go fast.
The requirements of each model are that they can accept a name upon initialization and set that property correctly. The name
property should be readable and writeable by the object.
Song.new("Blank Space").name #=> "Blank Space"`
Additionally, each class should contain a class variable @@all
that is set to an empty array and is prepared to store all saved instances. This class variable should be accessible via the class method .all
.
Song.all #=> []
Instances should respond to a #save
method that adds the instance itself into the class variable @@all
.
Song.new("Blank Space").save
Song.all #=> [#<Song: @name="Blank Space">]
The class should be able to empty its @@all
array via a class method .destroy_all
.
Song.new("Blank Space").save
Song.all #=> [#<Song: @name="Blank Space">]
Song.destroy_all
Song.all #=> []
Finally, all classes should implement a custom constructor .create
that instantiates an instance using .new
but also evokes #save
on that instance, forcing it to persist immediately.
Song.new("Blank Space")
Song.all #=> []
Song.create("Blank Space")
Song.all #=> [#<Song: @name="Blank Space">]
- Songs belong to an Artist and an Artist has many songs. Adding a song to an Artist is done by calling an
#add_song
method on an instance of theArtist
class - Songs can be initialized with an optional
Artist
argument
- Genres have many songs and are initialized with an empty list of songs
- Songs have one genre
- Songs can be initialized with an optional genre
Artist
s have manyGenre
s throughSong
. Implement a#genres
method for this association.Genre
s have manyArtists
s throughSong
. Implement a#artists
method for this association.
First implement the following two methods in your Song
class
- Songs should have a
find_by_name
method. - Songs should have a
find_or_create_by_name
method.
Now that you've done that, let's generalize those methods by putting them into a module and then including that module in the Genre
and Artist
class.
- Implement a generic
#find_by_name
method that uses the.all
method defined by the class to find by name. - Implement a generic
#find_or_create_by_name
method that uses the.all
method defined by the class. - Add this module to your
Genre
andArtist
class.
Create a Music Importer class to work with your Song
, Genre
and Artist
objects to import a directory of mp3s. This class will have the following methods:
- Initialize accepts a file path of mp3 files
- A
#files
method that will return all of the filenames - Add a new method to the
Song
class called.new_from_filename
that creates aSong
based on a filename - Add a new method to the
Song
class called.create_from_filename
that creates aSong
based on a filename and saves it to the@@all
class variable - In your
MusicImporter
class, add an.import
method that imports all the files from the library and creates theSong
objects.
Congrats! You've done the heavy lifting. Now let's wrap it all up in a CLI so that users can actually interact with our code.
- It initializes with an optional path to the music, but defaults to
./db/mp3s
. It creates aMusicImporter
and imports the music. - Add a
#call
method that starts the CLI and asks the user for input. Check out the tests for specifics.
View Ruby Music Library on Learn.co and start learning to code for free.
View Music Library CLI on Learn.co and start learning to code for free.