Rails模型关系has_many当属

Question

I have a model Match and a model Team , each Match has two teams and each Team can have multiple Matches .

Team: name:string

Match name:string team1:references team2:references

So my models look like this.

class Match < ActiveRecord::Base
  belongs_to :team1, :class_name => Team, :foreign_key => "team1_id"
  belongs_to :team2, :class_name => Team, :foreign_key => "team2_id"
end

class Team < ActiveRecord::Base
  has_many :matches
end

I want to be able to create a new Team through a Match. And I don't want either duplicate Match records nor Team records. I am kinda lost, if this association is the right one between Team and Match.

Answer 1

Here you should use has_and_belongs_to_many relationship.

Match.rb

class Match < ActiveRecord::Base
  has_and_belongs_to_many :teams
end

Team.rb

class Team < ActiveRecord::Base
  has_and_belongs_to_many :matches
end

And generate a migration to create table to associate teams and matches with each other:

rails g migration create_matches_teams_table

Then in generated migration file:

class CreateMatchTeams < ActiveRecord::Migration
  def self.up
    create_table :matches_teams, :id => false do |t|   # :id => false; is to  prevent the creation of primary key
        t.integer :match_id
        t.integer :team_id
    end
  end

  def self.down
    drop_table :matches_teams
  end
end

Then run this migration, and you can associate teams and matches with each other via habtm relationship.

Answer 2

try something like this:

class Match < ActiveRecord::Base
  #home team
  belongs_to :team1, :class_name => Team, :foreign_key => "team1_id"
  #away team
  belongs_to :team2, :class_name => Team, :foreign_key => "team2_id"

  #this should only allow 1 match between each team
  validates :team1_id, :uniqueness => { :scope => :team2_id }
end

class Team < ActiveRecord::Base
  has_many :home_matches, :class_name => Match, :foreign_key => "team1_id"
  has_many :away_matches, :class_name => Match, :foreign_key => "team2_id"

  validates :name, :uniqueness => true

  def matches
    Match.where("team1_id = ? OR team2_id = ?", self.id, self.id)
  end
end