Answers for "many to many sequelize"

many to many sequelize

const { Sequelize, Op, Model, DataTypes } = require('sequelize');
const sequelize = new Sequelize('sqlite::memory:', {
  define: { timestamps: false } // Just for less clutter in this example
});
const Player = sequelize.define('Player', { username: DataTypes.STRING });
const Team = sequelize.define('Team', { name: DataTypes.STRING });
const Game = sequelize.define('Game', { name: DataTypes.INTEGER });

// We apply a Super Many-to-Many relationship between Game and Team
const GameTeam = sequelize.define('GameTeam', {
  id: {
    type: DataTypes.INTEGER,
    primaryKey: true,
    autoIncrement: true,
    allowNull: false
  }
});
Team.belongsToMany(Game, { through: GameTeam });
Game.belongsToMany(Team, { through: GameTeam });
GameTeam.belongsTo(Game);
GameTeam.belongsTo(Team);
Game.hasMany(GameTeam);
Team.hasMany(GameTeam);

// We apply a Super Many-to-Many relationship between Player and GameTeam
const PlayerGameTeam = sequelize.define('PlayerGameTeam', {
  id: {
    type: DataTypes.INTEGER,
    primaryKey: true,
    autoIncrement: true,
    allowNull: false
  }
});
Player.belongsToMany(GameTeam, { through: PlayerGameTeam });
GameTeam.belongsToMany(Player, { through: PlayerGameTeam });
PlayerGameTeam.belongsTo(Player);
PlayerGameTeam.belongsTo(GameTeam);
Player.hasMany(PlayerGameTeam);
GameTeam.hasMany(PlayerGameTeam);

(async () => {

  await sequelize.sync();
  await Player.bulkCreate([
    { username: 's0me0ne' },
    { username: 'empty' },
    { username: 'greenhead' },
    { username: 'not_spock' },
    { username: 'bowl_of_petunias' }
  ]);
  await Game.bulkCreate([
    { name: 'The Big Clash' },
    { name: 'Winter Showdown' },
    { name: 'Summer Beatdown' }
  ]);
  await Team.bulkCreate([
    { name: 'The Martians' },
    { name: 'The Earthlings' },
    { name: 'The Plutonians' }
  ]);

  // Let's start defining which teams were in which games. This can be done
  // in several ways, such as calling `.setTeams` on each game. However, for
  // brevity, we will use direct `create` calls instead, referring directly
  // to the IDs we want. We know that IDs are given in order starting from 1.
  await GameTeam.bulkCreate([
    { GameId: 1, TeamId: 1 },   // this GameTeam will get id 1
    { GameId: 1, TeamId: 2 },   // this GameTeam will get id 2
    { GameId: 2, TeamId: 1 },   // this GameTeam will get id 3
    { GameId: 2, TeamId: 3 },   // this GameTeam will get id 4
    { GameId: 3, TeamId: 2 },   // this GameTeam will get id 5
    { GameId: 3, TeamId: 3 }    // this GameTeam will get id 6
  ]);

  // Now let's specify players.
  // For brevity, let's do it only for the second game (Winter Showdown).
  // Let's say that that s0me0ne and greenhead played for The Martians, while
  // not_spock and bowl_of_petunias played for The Plutonians:
  await PlayerGameTeam.bulkCreate([
    // In 'Winter Showdown' (i.e. GameTeamIds 3 and 4):
    { PlayerId: 1, GameTeamId: 3 },   // s0me0ne played for The Martians
    { PlayerId: 3, GameTeamId: 3 },   // greenhead played for The Martians
    { PlayerId: 4, GameTeamId: 4 },   // not_spock played for The Plutonians
    { PlayerId: 5, GameTeamId: 4 }    // bowl_of_petunias played for The Plutonians
  ]);

  // Now we can make queries!
  const game = await Game.findOne({
    where: {
      name: "Winter Showdown"
    },
    include: {
      model: GameTeam,
      include: [
        {
          model: Player,
          through: { attributes: [] } // Hide unwanted `PlayerGameTeam` nested object from results
        },
        Team
      ]
    }
  });

  console.log(`Found game: "${game.name}"`);
  for (let i = 0; i < game.GameTeams.length; i++) {
    const team = game.GameTeams[i].Team;
    const players = game.GameTeams[i].Players;
    console.log(`- Team "${team.name}" played game "${game.name}" with the following players:`);
    console.log(players.map(p => `--- ${p.username}`).join('\n'));
  }

})();