How to structure relationships between models in Ruby On Rails

Question

I'm developing an application to schedule soccer matches for two teams at a time. So, for example I need to schedule a match for two teams, but I'm not sure how can I structure the database relation between these two entities.

One solution I thought is a relation many to many between them, and in the Associative Table(match_teams) I put a is_visitor field, to indicate which team is playing outside home:

team model:

class Team < ApplicationRecord
    has_many :match_team
    has_many :matches, through: :match_team
end

match model:

class Match < ApplicationRecord
    has_many :match_team
    has_many :teams, through: :match_team
end

match_team model:

class MatchTeam < ApplicationRecord
  belongs_to :match
  belongs_to :team
end

team migration:

class CreateTeams < ActiveRecord::Migration[5.1]
  def change
    create_table :teams do |t|
      t.timestamps
    end
  end
end

match migration:

class CreateMatches < ActiveRecord::Migration[5.1]
  def change
    create_table :matches do |t|
      t.timestamps
    end
  end
end

match_teams migration:

class CreateMatchTeams < ActiveRecord::Migration[5.1]
  def change
    create_table :match_teams do |t|
        t.belongs_to :match, index: true, foreign_key: true
        t.belongs_to :team, index: true, foreign_key: true
        t.boolean "is_visitor", default: false
      t.timestamps
    end
  end
end

So, I can do something like:

#create team here
#create team2 here

match = Match.new()
match.teams = [team, team2]
match.save!

match_team_associative = match.match_team
match_team_associative.each do |item|
  if item.team_id == team.id
    item.is_visitor = true
    item.save!
  end
end

I don't know if this is the better solution, or if it's ok the manner I'm changing the value of is_visitor field in the associative table.

Another soluction I think would be has two relations one to many between these entitties team and match. A table matches would have a foreign key for teams called team, and another foreign key for teams called visitor_team, like:

matches table:

id | team | visitor_team
1  |    1 | 2

But this second soluction I could't implement, I don't know how to do that. I find something here but I could't make it work. Does anyone can help me telling me how to make it work that way?

Which of these two solution is better? I think maybe the second, but it couldn't make it work.

I appreciate any help.

Thank you.

score 1 · Answer 1 · answered Dec 06 '17 at 14:00

The logic is, to have a match, and two teams in a match. One team will be hosting and one will be a visitor. Even if they play on neutral ground one team is still technically a host.

class Team < ApplicationRecord
  has_many :hosted_matches, class_name: 'Match', foreign_key: :hosting_team_id
  has_many :visited_matches, class_name: 'Match', foreign_key: :visiting_team_id
end

class Match < ApplicationRecord
  belongs_to :hosting_team, class_name: 'Team'
  belongs_to :visiting_team, class_name: 'Team'
end

...    

# create team here
# create team2 here

match = Match.new(hosting_team: team, visiting_team: team2)
match.save!

Migrations

class CreateTeams < ActiveRecord::Migration[5.1]
  def change
    create_table :teams do |t|
      t.timestamps
    end
  end
end

class CreateMatches < ActiveRecord::Migration[5.1]
  def change
    create_table :matches do |t|
      t.integer :hosting_team_id
      t.integer :visiting_team_id
      t.timestamps
    end
  end
end

Thank you Nermin, It helped a lot! But I noticed that in the table matches the fields hosting_team_id and visiting_team_id are not foreign keys. How can I mark them to be foreign keys? — Bruno, Dec 17 '17 at 16:37

How to structure relationships between models in Ruby On Rails

1 Answers1