How to define people and movies' association?

Rails
1

I want to make a app similar to www.imdb.com, now I have a problem to
define the association of two table --people and movies .
Movie stars, movie writers… are allow people, I plan to put all people
data into one table named “people”, and I’ll use “movies” table to store
movies’ information. A movie may have none or more than one movie
writer/ movie star information, and a movie star may show up on several
movies.

I want to make association between people table and movies, in such a
way that I can list all movie stars who shown on one movie with
movie.movie_stars, and writers with movie.writers, while
movie.movie_writers << person will add a movie writer info.

Here’s my current idea:
A third table,named “movies_people”, containing movie_id, person_id,
char_type columns, is to be added. char_type column is used to store
person’s role in the movie, like “movie_star” to identify the person is
added as a movie star.

MoviesPeople Class

belongs_to :movie
belongs_to :person

Movie Class

has_many :movies_people

Person Class

has_many :person

Add methods to Movie.rb, like:

def movie_stars
Person.find(movies_people.find_by_char_type(“movie_star”).collect{|o| o.person_id})
end

The question is: is that a good idea, or there are better ones?

2

How about a roles table?

Class Rol < AR::Base
has_many :participations
has_many :people, :through => :participations
end

Class Person < AR::Base
has_many :participations
has_many :movies, :through => :participations
has_many :roles, :through => :participations
end

Class Participation < AR::Base
belongs_to :rol
belongs_to :person
belongs_to :movie
end

Class Movie < AR::Base
has_many :participations
has_many :persons, :through => :participations
end

ie
Person.participations => may bring an array of participation objects,
like

[[person, movie, rol], …] => [[“John”, “A Movie”, “Actor”], [“John”,
“Another Movie”, “Director”], …]

Person.movies returns all the movies of the person.

Rol.find_by_name(“Actors”).people => Return all the persons that have
record on partipation in the role of actor.

THE PROBLEM: With this system you can’t assign a person a rol if it has
not acted in a movie sometime, ie: you can’t know if a person is an
actor until he actually acts in a movie!. You could add another table to
state the people => rol relationship, even if they have not participated
yet on a movie:

make a table people_roles => person_id, rol_id, whitout an ActiveRecord
class, and add add:

has_and_belongs_to_many :roles to class People and
has_and_belongs_to_many :people to class Rol

YES! it’s a messy response to a messy problem :slight_smile:

3

Nanyang Z. wrote:

Here’s my current idea:
A third table,named “movies_people”, containing movie_id, person_id,
char_type columns, is to be added. char_type column is used to store
person’s role in the movie, like “movie_star” to identify the person is
added as a movie star.

MoviesPeople Class

belongs_to :movie
belongs_to :person

Movie Class

has_many :movies_people

Person Class

has_many :person

Add methods to Movie.rb, like:

def movie_stars
Person.find(movies_people.find_by_char_type(“movie_star”).collect{|o| o.person_id})
end

The question is: is that a good idea, or there are better ones?

A movie has many people and a person belongs to a movie, or you could do
a HABTM association so a movie has and belongs to many people and a
person has and belongs to many movies.

~Jeremy

4

Jeremy W. wrote:

a HABTM association so a movie has and belongs to many people and a
person has and belongs to many movies.

A habtm association can not tell the role of one person that
participated for the movie.

5

Emmanuel O. wrote:

How about a roles table?

Class Participation < AR::Base
belongs_to :rol
belongs_to :person
belongs_to :movie
end

A participation model! It sounds attractive.With this model, the
relation of people and movies is clearer.

ie
Person.participations => may bring an array of participation objects,
like

[[person, movie, rol], …] => [[“John”, “A Movie”, “Actor”], [“John”,
“Another Movie”, “Director”], …]

Person.movies returns all the movies of the person.
Good. But it seems all the favors go to the people part. How to make
movie.actors show all the actors of one movie?

THE PROBLEM: With this system you can’t assign a person a rol if it has
not acted in a movie sometime, ie: you can’t know if a person is an
actor until he actually acts in a movie!.

Then, just let it be. Maybe people wouldn’t notice an actor without an
movie.

make a table people_roles => person_id, rol_id, whitout an ActiveRecord
class, and add add:

has_and_belongs_to_many :roles to class People and
has_and_belongs_to_many :people to class Rol

…All sounds good, except one thing:I came here looking for a simple
solution.