Node.js的ORM映射器Sequelize的关联

1 年 ago
雅, 悟
4 minutes

协会的总结

属于

具有一个相关性。

    例) Players.belongsTo(Teams)

球员表将自动添加外键teamId。

只有一个

具有一个相关。

    例) Players.hasOne(Profiles)

在Profiles表中，将添加一个外键playerId，并且该外键是自动追加的。在进行include操作时，只会输出第一条记录。

拥有许多

具有多个关联。

    例) Players.hasMany(Profiles)

在 Profiles 表中，外键 playerId 会自动添加。在 include 时，会输出多个记录。

属于许多

具有多对多的中间表。

    • 例1)Players.belongsToMany(Teams, { through: TeamPlayers })

 

    • 中間テーブル’TeamPlayers’が作成され、そこに外部キーteamId playerIdが自動追加される

 

    • 例2)Teams.belongsToMany(Players, { through: TeamPlayers })

 

    中間テーブル’TeamPlayers’が作成され、そこに外部キーplayerId teamIdが自動追加される

belongTo和hasOne的区别在于

动作几乎相同，只是顺序发生了变化。

属于之样本

// model(テーブル)を定義
// 主キー`id`や`createdAt`、`updatedAt`は勝手に定義されるので記述不要
const Players = sequelize.define('players', {
    name: Sequelize.STRING,
});
const Teams = sequelize.define('teams', {
    name: Sequelize.STRING,
});
Players.belongsTo(Teams, { foreignKey: 'team_id' })   // playersに外部キー'team_id'が作成される。foreignKeyを省略した場合、キャメルケースでid名'teamId'が自動生成される

// modelを元にDBテーブルの作成({force:true}オプションは、テーブルdrop&create)
await Players.sync({ force: true });
await Teams.sync({ force: true });

// レコードのcreate
const team1 = await Teams.create({ name: 'team1' });
const player1 = await Players.create({ name: 'player1', team_id: team1.id });

// レコード取得
const player = await Players.findById(player1.id, { include: Teams })

console.log(player.get({ plain: true }))

输出结果

{ id: 1,
    name: 'player1',
    createdat: 2019-08-29t02:36:21.464z,
    updatedat: 2019-08-29t02:36:21.464z,
    team_id: 1,
    team:
    { id: 1,
    name: 'team1',
    createdat: 2019-08-29t02:36:21.448z,
    updatedat: 2019-08-29t02:36:21.448z } }

尽管以下可能通过团队 : 球员 = 1: n 的方式获得，但是无法实现。

const team = await Teams.findById(team1.id, { include: Players})

输出结果 (chū lì jié guǒ)

  failed: sequelizeeagerloadingerror: players is not associated to teams!

有一个示例

// model(テーブル)を定義
const Players = sequelize.define('players', {
    name: Sequelize.STRING,
});
const Profiles= sequelize.define('profiles', {
    name: Sequelize.STRING,
});
Players.hasOne(Profiles,{foreignKey:'player_id'})

// modelを元にDBテーブルの作成
await Players.sync({ force: true });
await Profiles.sync({ force: true });

// レコードのcreate
const player1= await Players.create({ name: 'player1' });
const profile1= await Profiles.create({ name: 'profile1', player_id: player1.id });
const profile2= await Profiles.create({ name: 'profile2', player_id: player1.id });

// レコードの取得
const player = await Players.findById(player1.id, { include: Profiles})

console.log(player.get({ plain: true }))

输出结果

{ id: 1,
    name: 'player1',
    createdAt: 2019-08-29T03:59:30.432Z,
    updatedAt: 2019-08-29T03:59:30.432Z,
    profile:
    { id: 1,
    name: 'profile1',
    createdAt: 2019-08-29T03:59:30.448Z,
    updatedAt: 2019-08-29T03:59:30.448Z,
    player_id: 1 } }

有许多示例

// model(テーブル)を定義
const Players = sequelize.define('players', {
    name: Sequelize.STRING,
});
const Profiles= sequelize.define('profiles', {
    name: Sequelize.STRING,
});
Players.hasMany(Profiles,{foreignKey:'player_id'})

// modelを元にDBテーブルの作成
await Players.sync({ force: true });
await Profiles.sync({ force: true });

// レコードのcreate
const player1= await Players.create({ name: 'player1' });
const profile1= await Profiles.create({ name: 'profile1', player_id: player1.id });
const profile2= await Profiles.create({ name: 'profile2', player_id: player1.id });

//　レコードの取得
const player = await Players.findById(player1.id, { include: Profiles})

// hasOneだと最初の１件しか取得できないがhasManyだと全て取得できる
console.log(player.get({ plain: true }))

输出结果

{ id: 1,
    name: 'player1',
    createdAt: 2019-08-29T04:13:05.396Z,
    updatedAt: 2019-08-29T04:13:05.396Z,
    profiles:
    [ { id: 1,
        name: 'profile1',
        createdAt: 2019-08-29T04:13:05.412Z,
        updatedAt: 2019-08-29T04:13:05.412Z,
        player_id: 1 },
    { id: 2,
        name: 'profile2',
        createdAt: 2019-08-29T04:13:05.428Z,
        updatedAt: 2019-08-29T04:13:05.428Z,
        player_id: 1 } ] }

属于多对多关系的示例

// model(テーブル)を定義
// 主キー'id'や'createdAt'、'updatedAt'は勝手に定義されるので記述不要
const Players = sequelize.define('players', {
    name: Sequelize.STRING,
});
const Teams = sequelize.define('teams', {
    name: Sequelize.STRING,
});
const TeamPlayers = sequelize.define('team_players', {
    name: Sequelize.STRING,
});

// 中間テーブル'TeamPlayers'を作成し、そこに'team_id'を追加する
Players.belongsToMany(Teams, { through: TeamPlayers, foreignKey: 'team_id' }) 
// 中間テーブル'TeamPlayers'を作成し、そこに'team_id'を追加する
Teams.belongsToMany(Players, { through: TeamPlayers, foreignKey: 'player_id' })

await TeamPlayers.sync({ force: true });
await Players.sync({ force: true });
await Teams.sync({ force: true });

// レコードのcreate
const team1 = await Teams.create({ name: 'team1' });
const team2 = await Teams.create({ name: 'team2' });
const player1 = await Players.create({ name: 'player1' });
player1.addTeam(team1,{ status: 'started' })
player1.addTeam(team2,{ status: 'started' })
const player2 = await Players.create({ name: 'player2' });
player2.addTeam(team1,{ status: 'started' })
player2.addTeam(team2,{ status: 'started' })

// レコード取得
const player = await Players.findById(player1.id, { include: Teams })
console.log(player.get({ plain: true }))

const team= await Teams.findById(team1.id, { include: Players})
console.log(team.get({ plain: true }))

输出结果

{ id: 1,
  name: 'player1',
  createdAt: 2019-08-29T05:56:11.200Z,
  updatedAt: 2019-08-29T05:56:11.200Z,
  teams:
   [ { id: 1,
       name: 'team1',
       createdAt: 2019-08-29T05:56:11.168Z,
       updatedAt: 2019-08-29T05:56:11.168Z,
       team_players: [Object] },
     { id: 2,
       name: 'team2',
       createdAt: 2019-08-29T05:56:11.184Z,
       updatedAt: 2019-08-29T05:56:11.184Z,
       team_players: [Object] } ] }

{ id: 1,
  name: 'team1',
  createdAt: 2019-08-29T05:56:11.168Z,
  updatedAt: 2019-08-29T05:56:11.168Z,
  players:
   [ { id: 1,
       name: 'player1',
       createdAt: 2019-08-29T05:56:11.200Z,
       updatedAt: 2019-08-29T05:56:11.200Z,
       team_players: [Object] },
     { id: 2,
       name: 'player2',
       createdAt: 2019-08-29T05:56:11.217Z,
       updatedAt: 2019-08-29T05:56:11.217Z,
       team_players: [Object] } ] }
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