Help with model!! Do I need to use a model as a join table?

rubyonrails-talk
1

HI all, newbie question, I'm not sure exactly how I should model the following DB Structure, do I need to use a model as a join table? Here is my database

actors - id - name - age

movie - id - name - year

role - id - name - requiresSwimming - requiresHorseskills

movie_actor - actor_id - movie_id - role_id

How should I map this in my model in rails? An actor can only have one role in each movie.

class Role < ActiveRecord::Base end

class Movie < ActiveRecord::Base end

class Actor < ActiveRecord::Base end

Thanks J

2

Well, if each Role belongs to 1 specific movie and 1 actor, you don't even need the movie_actor table... us a has_many :thorugh relationship, and roles as the join table....

actors - id - name - age

movie - id - name - year

role - id - movie_id - actor_id - name - requiresSwimming - requiresHorseskills

class Role < ActiveRecord::Base belongs_to :movie belongs_to :actor end

class Movie < ActiveRecord::Base has_many :roles has_many :actors, :through => :roles end

class Actor < ActiveRecord::Base has_many :roles has_many :movies, :through => :roles end

@actor= Movie.find(1).roles[1].actor # find the actor who plays the first role in the first movie

3

I can't do that because the Roles are a standard set e.g.

Leading Man Leading Lady

so although Tom Cruise can only be Leading Man once on Mission Impossible, Tom can also be Leading man once on Mission Impossible 2

so I do need that actor_roles table

So how should I map that ?

J

4

ah ok i get it. the attributes like "requires_horseskills" made it look like indiviudal entries as opposed to a standard set. well then do this:

actors - id - name - age

movie - id - name - year

role - id - name - requiresSwimming - requiresHorseskills

Appearance - id - movie_id - actor_id - role_id

class Role < ActiveRecord::Base   has_many :appearances   has_many :movies, :through => :appearances   has_many :actors, :through => :appearances end

class Movie < ActiveRecord::Base   has_many :appearances   has_many :actors, :through => :appearances   has_many :roles, :through => :appearances end

class Actor < ActiveRecord::Base   has_many :appearances   has_many :movies, :through => :appearances   has_many :roles, :through => :appearances

end

class Appearance < ActiveRecord::Base   belongs_to :movie   belongs_to :actor   belongs_to :role end

... so now the Model Appearance is the center of the 3 others, and each of those can find it's corresponding items in the other 2 throught the appeances join table.

5

Thanks I'll try that