一、生成模型 Game(游戏表)GameGrades(游戏成绩表)GameUser（用户表）

1.1 对非中间表 做多对多逻辑处理

• Game模型

static associate(models) {
  // define association here
  models.GameUser.belongsToMany(models.Game, {
    through: models.GameGrade,
    foreignKey: 'userId',
    as: 'GameGradesUser'
  })
}

• GameUser模型

 static associate(models) {
   // define association here
   models.GameUser.belongsToMany(models.Game, {
     through: models.GameGrade,
     foreignKey: 'userId',
     as: 'GameGradesUser'
   })
 }

对中间表 做逻辑处理

• GameGrades 模型

 models.GameGrade.belongsTo(models.Game, {foreignKey: 'gameId'})
 models.GameGrade.belongsTo(models.GameUser, {foreignKey: 'userId'})

二、某一游戏根据游戏降序排名

主要代码:通过搜索中间表关联 两张表

 const query = req.query;
 const currentPage = Math.abs(Number(query.currentPage)) || 1;
 const pageSize = Math.abs(Number(query.pageSize)) || 10;
 const offset = (currentPage - 1) * pageSize;

const gameList = await GameGrade.findAll({
  where: {
    gameId: IsExistGame.id
  },
  attributes: ['grade'], // GameGrade表中要显示的字段
  order: [['grade', 'desc']], // 排序方式
  limit: pageSize, // 一页多少条
  offset, // 偏移量
  include: [{
    model: Game, attributes: ['name'] // 关联表 及显示的字段
  }, {
    model: GameUser, attributes: ['name', 'avatar'] // 关联表 及显示的字段
  }]
})

完整代码:

router.get('/', async function (req, res) {
  // currentPage pageSize gameName
  try {
    const query = req.query;
    const currentPage = Math.abs(Number(query.currentPage)) || 1;
    const pageSize = Math.abs(Number(query.pageSize)) || 10;
    const offset = (currentPage - 1) * pageSize;
	// 是否存在游戏
    const IsExistGame = await Game.findOne({
      where: {
        name: query.gameName
      }
    })
    // 数据库没有游戏
    if (!IsExistGame) {
      throw new NotFound(`ID: ${ query.gameName}不存在。`)
    }

    const rankList = await GameGrade.findAll({
      where: {
        gameId: IsExistGame.id
      },
      attributes: ['grade'],
      order: [['grade', 'desc']],
      limit: pageSize,
      offset,
      include: [{
        model: Game, attributes: ['name']
      }, {
        model: GameUser, attributes: ['name', 'avatar']
      }]
    })
	// 格式化数据
    const formattedRankList = rankList.map(item => ({
      username: item.GameUser.name,
      game: item.Game.name,
      grade: item.grade,
      avatar: item.GameUser.avatar
    }));
    success(res, '查询成功', formattedRankList)


  } catch
    (error) {
    failure(res, error);

  }
})

格式化后