我有一个模型Link和另外两个模型Overlay和Tracker。两者都与Link模型有很多关系。数据在MySQL数据库中。
Overlay和Tracker与Link使用相同的关联，但是当我尝试使用顺序查询来加载它们时，Tracker的值始终为null（返回作为空数组）。
考虑此示例查询。
const result = await Link.findAndCountAll({
where: {
userId: req.user.id
},
limit: limit,
offset: offset,
order: [
['createdAt', 'DESC']
],
include: [
{model: Tracker, as: 'trackers'},
{model: Overlay, as: 'overlays'}
]
});
返回的结果正确包含overlays，但是trackers始终为空数组。我真的很困惑，因为两种模型的关联性都相同。
Link.js
'use strict';
module.exports = (sequelize, DataTypes) => {
const Link = sequelize.define('Link', {
name: DataTypes.STRING,
// ... removed for simplicity
}
}, {
freezeTableName: true,
tableName: 'links'
});
Link.associate = function(models) {
// associations can be defined here
Link.belongsTo(models.User, {
as: 'user',
foreignKey: 'userId'
});
Link.belongsToMany(models.Overlay, {
as: 'overlays',
through: models.LinkOverlays,
foreignKey: 'linkId',
targetKey: 'id',
});
Link.belongsToMany(models.Tracker, {
as: 'trackers',
through: models.LinkTrackers,
foreignKey: 'trackerId',
targetKey: 'id',
});
};
return Link;
};
Overlay.js
'use strict';
module.exports = (sequelize, DataTypes) => {
const Overlay = sequelize.define('Overlay', {
name: DataTypes.STRING(100),
// ... removed for simplicity
}, {
freezeTableName: true,
tableName: 'overlays'
});
Overlay.associate = function(models) {
// associations can be defined here
Overlay.belongsTo(models.User, {
foreignKey: 'userId'
});
Overlay.belongsToMany(models.Link, {
as: 'links',
through: models.LinkOverlays,
foreignKey: 'overlayId',
targetKey: 'id'
});
};
return Overlay;
};
Tracker.js
'use strict';
module.exports = (sequelize, DataTypes) => {
const Tracker = sequelize.define('Tracker', {
name: DataTypes.STRING(100),
// ...
}, {
freezeTableName: true,
timestamps: false,
tableName: 'trackers'
});
Tracker.associate = function(models) {
Tracker.belongsTo(models.User, {
foreignKey: 'userId'
});
Tracker.belongsToMany(models.Link, {
as: 'links',
through: models.LinkTrackers,
foreignKey: 'trackerId',
targetKey: 'id'
});
};
return Tracker;
};
对于两个关联的模型，创建的SQL查询似乎也相同。这是给定查询的结果SQL
SELECT `Link`.*,
`trackers`.`id` AS `trackers.id`,
`trackers`.`createdat` AS `trackers.createdAt`,
`trackers`.`name` AS `trackers.name`,
`trackers`.`vendor` AS `trackers.vendor`,
`trackers`.`vendortrackerid` AS `trackers.vendorTrackerId`,
`trackers`.`userid` AS `trackers.userId`,
`trackers->LinkTrackers`.`linkid` AS `trackers.LinkTrackers.linkId`,
`trackers->LinkTrackers`.`trackerid` AS `trackers.LinkTrackers.trackerId`
,
`overlays`.`id` AS `overlays.id`,
`overlays`.`name` AS `overlays.name`,
`overlays`.`type` AS `overlays.type`,
`overlays`.`config` AS `overlays.config`,
`overlays`.`userid` AS `overlays.userId`,
`overlays`.`createdat` AS `overlays.createdAt`,
`overlays`.`updatedat` AS `overlays.updatedAt`,
`overlays->LinkOverlays`.`linkid` AS `overlays.LinkOverlays.linkId`,
`overlays->LinkOverlays`.`overlayid` AS `overlays.LinkOverlays.overlayId`
FROM (SELECT `Link`.`id`,
`Link`.`name`,
`Link`.`originalurl`,
`Link`.`code`,
`Link`.`type`,
`Link`.`userid`,
`Link`.`hitcount`,
`Link`.`opengraph`,
`Link`.`createdat`,
`Link`.`updatedat`
FROM `links` AS `Link`
WHERE `Link`.`userid` = 1
ORDER BY `Link`.`createdat` DESC
LIMIT 0, 10) AS `Link`
LEFT OUTER JOIN ( `link_trackers` AS `trackers->LinkTrackers`
INNER JOIN `trackers` AS `trackers`
ON `trackers`.`id` =
`trackers->LinkTrackers`.`trackerid`)
ON `Link`.`id` = `trackers->LinkTrackers`.`trackerid`
LEFT OUTER JOIN ( `link_overlays` AS `overlays->LinkOverlays`
INNER JOIN `overlays` AS `overlays`
ON `overlays`.`id` =
`overlays->LinkOverlays`.`overlayid`)
ON `Link`.`id` = `overlays->LinkOverlays`.`linkid`
ORDER BY `Link`.`createdat` DESC;
下面是两个关系表模型
LinkOverlays.js
'use strict';
module.exports = (sequelize, DataTypes) => {
const LinkOverlays = sequelize.define('LinkOverlays', {
linkId: {
type: DataTypes.INTEGER,
primaryKey: true,
unique: 'linkIdOverlayIdComposite'
},
overlayId: {
type: DataTypes.INTEGER,
primaryKey: true,
unique: 'linkIdOverlayIdComposite'
}
}, {
freezeTableName: true,
timestamps: false,
tableName: 'link_overlays'
});
LinkOverlays.associate = function(models) {
// associations can be defined here
LinkOverlays.belongsTo(models.Link, {
foreignKey: 'linkId',
through: models.LinkOverlays,
targetKey: 'id'
});
// associations can be defined here
LinkOverlays.belongsTo(models.Overlay, {
foreignKey: 'overlayId',
through: models.LinkOverlays,
targetKey: 'id'
});
};
return LinkOverlays;
};
LinkTrackers.js
'use strict';
module.exports = (sequelize, DataTypes) => {
const LinkTrackers = sequelize.define('LinkTrackers', {
linkId: {
type: DataTypes.INTEGER,
primaryKey: true,
unique: 'linkIdTrackerIdComposite'
},
trackerId: {
type: DataTypes.INTEGER,
primaryKey: true,
unique: 'linkIdTrackerIdComposite'
}
}, {
freezeTableName: true,
timestamps: false,
tableName: 'link_trackers'
});
LinkTrackers.associate = function(models) {
LinkTrackers.belongsTo(models.Link, {
foreignKey: 'linkId',
through: models.LinkTrackers,
targetKey: 'id'
});
LinkTrackers.belongsTo(models.Tracker, {
foreignKey: 'trackerId',
through: models.LinkTrackers,
targetKey: 'id'
});
};
return LinkTrackers;
};
我已经尝试了许多小时来查找问题，但是失败了。最令人困惑的是，一个正在工作（Overlay），而另一个却没有工作（Tracker）
答案 0 :(得分：2)
在您的
link.js
Link.belongsToMany(models.Overlay, {
as: 'overlays',
through: models.LinkOverlays,
foreignKey: 'linkId',
targetKey: 'id',
});
Link.belongsToMany(models.Tracker, {
as: 'trackers',
through: models.LinkTrackers,
foreignKey: 'trackerId', // should be linkId
targetKey: 'id',
});
与LinkOverlays的关系通过linkId，但与LinkTrackers的关系通过trackerId，它也应为linkId