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Galactical Associations Koans

Confused about db relationships and writing migrations in Rails? These koans are intended as a learning tool just for you.

Instructions

1. Clone the repository.
2. Run bundle install
3. Create the database: rake db:create
4. Run rake galaxy to work progressively through the problems. Alternatively, run a single stage with rake galaxy:stage, e.g rake galaxy:beta.

Stages

In the domain we have: planets, moons, a sun, and asteroids.

Alpha

• Suns have many planets.
• Planets belongs to a sun.

Beta

• Planets have many moons.
• Moons belong to a planet.

Gamma

• Planets have many asteroids.
• Asteroids have many planets.

Delta

• A spaceship has many astronauts, via crewings.
• Astronauts have many spaceships, via crewings.
• A spaceship can have a captain.
• An astronaut can be a captain of a spaceship.

Epsilon

• Suns have many moons, through planets.
• Moons have a single Sun, through a planet.