如何在 Sequelize 中急切加载多个外键，包括来自同一个表的 or 查询？

Question

我正在搜索 Captain.entry_date，但我无法在 sequelize 模型中创建查询。
我的问题是，对于任何船都存在船长，但 ship_captain.captain_id 有时为空。
对于这种情况，可以找到有关 route_id 的船长。

4 Tables : 
    ship, attributes:[id,name], 
    captain, attributes: [id, name, route_id, route_date]
    ship_captain, attributes: [id, ship_id, route_id, captain_id]
    route, attributes: [id, name]

select ship.name, c.name, c.entry_date 
    from ship left join ship_captain sc on ship.id = sc.ship_id 
            left join captain c on c.id = sc.captain_id or c.route_id = sc.route_id

到目前为止我尝试过的是这样，但我不能将 OR 运算符加入到最后的连接中

Ship.hasMany(ShipCaptain, {foreignKey: "ship_id"});
ShipCaptain.belongsTo(Ship, {foreignKey: "ship_id"});
Captain.hasMany(ShipCaptain, {as: "ship_captain_by_id", foreignKey: "captain_id"});
ShipCaptain.belongsTo(Captain, {as: "ship_captain_by_route", foreignKey: "captain_id"});
Captain.hasMany(ShipCaptain, {as: "ship_captain_by_route", foreignKey: "route_id"});
ShipCaptain.belongsTo(Captain, {as: "ship_captain_by_route", foreignKey: "route_id"});

const options = {
    attributes: ["name"],
    include: [
          {
            model: Captain,
            as: 'ship_captain_per_id',
            required: false,
            attributes: ["name","route_date"],
          },
          {
            model: Captain,
            as: 'ship_captain_per_route',
            required: false,
            attributes: ["name","route_date"],
          }
        ],
    }
    
const elements = await Ship.findAll(options);

这只是一个示例代码，可能是你想重新排列 db 属性
但我尽力澄清问题。我无法更改客户数据库。

Answer 1

如果您真的只想使用一个关联来通过captain_id 或route_id 获得船长，而不是使用两个关联并自己映射它们，那么您只需要定义一个关联hasOne（而不是@987654324 @) 和总是使用on 选项将ShipCaptain 与Captain 加入OR：

Ship.hasMany(ShipCaptain, {foreignKey: "ship_id"});
ShipCaptain.belongsTo(Ship, {foreignKey: "ship_id"});
ShipCaptain.belongsTo(Captain, {as: "captain_by_captain", foreignKey: "captain_id"});
...
const options = {
    attributes: ["name"],
    include: [
          {
            model: ShipCaptain,
            required: false,
            include: [{
              model: Captain,
              required: false,
              as: 'captain_by_captain',
              attributes: ["name","route_date"],
              on: {
                [Op.or]: [{
                   id: Sequelize.col('ship_captain.captain_id'
                }, {
                   id: Sequelize.col('ship_captain.route_id'
                }]
              }
            }
            ]
          },
        ],
    }
    
const elements = await Ship.findAll(options);