Destroy and rebuild the database with simple data
rails test:wipe
Enter Rails Console
rails c
Show which albums this Artist has
Artist.first.albums
Show the tracks from within an album
Artist.first.albums.first.tracks
Show the name of the song starting from Artist > Album > Track > Song
Artist.first.albums.first.tracks.first.song.title
Find the artist this songs belongs to
Song.first.artist
Get the album a song belongs to
Song.first.track.album
Get the tracks from a specific album
Album.second.tracks
Show the artist this album belongs to
Album.first.artist
Find the songs with the title "Sad But True"
Song.where("title = 'Sad But True'", Song.pluck(:title))
Find the songs with the text "sad" within the title
Song.where("title ILIKE ?", "%sad%")
- An artist has many songs <> Songs belong to artists
- An artist has many albums <> Albums belong to artists
- An album has many tracks <> Tracks belong to albums <> Tracks have one song
- Songs belong to many albums through tracks
I want to be able to:
- Access an artist starting with a song
Song.first.artist
- Access an album starting from a song
Song.find_by_title("Enter Sandman").tracks.first.album
- Access a song starting from a artist
Artist.find_by_name("Metallica").albums.first.tracks.first.song
- Access a track's order starting from a song
Song.first.albums.first.tracks.first.order
- Access all the albums this song can be found on
Song.first.albums
Alternative Method
Song.first.tracks.album
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https://gorails.com/episodes/comments-with-polymorphic-associations
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http://6ftdan.com/allyourdev/2015/02/10/rails-polymorphic-models/
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https://www.sitepoint.com/brush-up-your-knowledge-of-rails-associations/
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http://6ftdan.com/allyourdev/2015/02/10/rails-polymorphic-models/
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http://6ftdan.com/allyourdev/2014/08/01/manual-polymorphic-creation-in-rails/