https://github.com/chrisjmendez/rails-associations
Simple relationships using Ruby on Rails and PostgreSQL.
https://github.com/chrisjmendez/rails-associations
Last synced: 3 months ago
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Simple relationships using Ruby on Rails and PostgreSQL.
- Host: GitHub
- URL: https://github.com/chrisjmendez/rails-associations
- Owner: chrisjmendez
- Created: 2016-11-29T18:42:59.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2017-01-04T03:43:10.000Z (over 8 years ago)
- Last Synced: 2025-01-25T17:28:53.612Z (5 months ago)
- Language: Ruby
- Homepage: http://www.chrisjmendez.com/2016/12/21/rails-database-relationships/
- Size: 46.9 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Rails Console
Destroy and rebuild the database with simple data
```language-powerbash
rails test:wipe
```
Enter Rails Console
```language-powerbash
rails c
```
Show which albums this Artist has
```language-powerbash
Artist.first.albums
```
Show the tracks from within an album
```language-powerbash
Artist.first.albums.first.tracks
```
Show the name of the song starting from ```Artist``` > ```Album``` > ```Track``` > ```Song```
```language-powerbash
Artist.first.albums.first.tracks.first.song.title
```
Find the artist this songs belongs to
```language-powerbash
Song.first.artist
```
Get the album a song belongs to
```language-powerbash
Song.first.track.album
```
Get the tracks from a specific album
```language-powerbash
Album.second.tracks
```
Show the artist this album belongs to
```language-powerbash
Album.first.artist
```
Find the songs with the title "Sad But True"
```language-powerbash
Song.where("title = 'Sad But True'", Song.pluck(:title))
```
Find the songs with the text "sad" within the title
```language-powerbash
Song.where("title ILIKE ?", "%sad%")
```
---
# Goals
- 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
```
---
# Resources
- [https://gorails.com/episodes/comments-with-polymorphic-associations](https://gorails.com/episodes/comments-with-polymorphic-associations)
- [http://railscasts.com/episodes/154-polymorphic-association](http://railscasts.com/episodes/154-polymorphic-association)
- [http://6ftdan.com/allyourdev/2015/02/10/rails-polymorphic-models/](http://6ftdan.com/allyourdev/2015/02/10/rails-polymorphic-models/)
- [https://www.sitepoint.com/brush-up-your-knowledge-of-rails-associations/](https://www.sitepoint.com/brush-up-your-knowledge-of-rails-associations/)
- [http://6ftdan.com/allyourdev/2015/02/10/rails-polymorphic-models/](http://6ftdan.com/allyourdev/2015/02/10/rails-polymorphic-models/)
- [http://6ftdan.com/allyourdev/2014/08/01/manual-polymorphic-creation-in-rails/](http://6ftdan.com/allyourdev/2014/08/01/manual-polymorphic-creation-in-rails/)
- [https://github.com/danielpclark/PolyBelongsTo](https://github.com/danielpclark/PolyBelongsTo)
- [PolyBelongsTo gem](https://github.com/danielpclark/PolyBelongsTo)