我正在尝试了解Sequelize中的关联.我从现有的数据库表开始,因此某些字段可能与Sequelize中的默认值不匹配.我使用Sequelizer直接从数据库生成模型.
我习惯于编写查询,但是现在我试图学习像Sequelize这样的ORM的工作方式.
这是我的模特.
型号/user.js
module.exports = (sequelize, DataTypes) => {
const User = sequelize.define(
"User",
{
id: {
type: DataTypes.INTEGER(11),
allowNull: false,
primaryKey: true,
field: "id"
},
username: {
type: DataTypes.STRING(20),
allowNull: false,
field: "username"
},
fullname: {
type: DataTypes.STRING(60),
allowNull: false,
field: "fullname"
},
createdat: {
type: DataTypes.DATE,
allowNull: false,
field: "createdat"
},
updateat: {
type: DataTypes.DATE,
allowNull: true,
field: "updateat"
},
deletedat: {
type: DataTypes.DATE,
allowNull: true,
field: "deletedat"
}
},
{
tableName: "users",
timestamps: false
}
);
User.associate = function(models) {
models.User.hasMany(models.Ticket),
{ as: "createdbyname", foreignKey: "createdby" };
};
return User;
};
models / ticket.js
module.exports = (sequelize, DataTypes) => {
const Ticket = sequelize.define(
"Ticket",
{
id: {
type: DataTypes.INTEGER(11),
allowNull: false,
primaryKey: true,
field: "id"
},
details: {
type: DataTypes.STRING(45),
allowNull: true,
field: "details"
},
assignedto: {
type: DataTypes.INTEGER(11),
allowNull: true,
field: "assignedto"
},
createdby: {
type: DataTypes.INTEGER(11),
allowNull: true,
field: "createdby"
},
createdat: {
type: DataTypes.DATE,
allowNull: false,
field: "createdat"
},
updatedat: {
type: DataTypes.DATE,
allowNull: true,
field: "updatedat"
},
deletedat: {
type: DataTypes.DATE,
allowNull: true,
field: "deletedat"
}
},
{
tableName: "tickets",
timestamps: false
}
);
Ticket.associate = function(models) {
models.Ticket.belongsTo(models.User,
{ foreignKey: "createdby" });
};
return Ticket;
};
在我的路由处理程序中,我按如下方式调用User.findAll:
models.User.findAll({
include: [models.Ticket]
})
我希望看到的结果是一个查询,如下所示:
SELECT
`User`.`id`,
`User`.`username`,
`User`.`fullname`,
`User`.`createdat`,
`User`.`updateat`,
`User`.`deletedat`,
`Tickets`.`id` AS `Tickets.id`,
`Tickets`.`details` AS `Tickets.details`,
`Tickets`.`assignedto` AS `Tickets.assignedto`,
`Tickets`.`createdby` AS `Tickets.createdby`,
`Tickets`.`createdat` AS `Tickets.createdat`,
`Tickets`.`updatedat` AS `Tickets.updatedat`,
`Tickets`.`deletedat` AS `Tickets.deletedat`
FROM
`users` AS `User`
LEFT OUTER JOIN
`tickets` AS `Tickets` ON `User`.`id` = `Tickets`.`createdby`
我看到在控制台中运行的查询是:
SELECT
`User`.`id`,
`User`.`username`,
`User`.`fullname`,
`User`.`createdat`,
`User`.`updateat`,
`User`.`deletedat`,
`Tickets`.`id` AS `Tickets.id`,
`Tickets`.`details` AS `Tickets.details`,
`Tickets`.`assignedto` AS `Tickets.assignedto`,
`Tickets`.`createdby` AS `Tickets.createdby`,
`Tickets`.`createdat` AS `Tickets.createdat`,
`Tickets`.`updatedat` AS `Tickets.updatedat`,
`Tickets`.`deletedat` AS `Tickets.deletedat`,
`Tickets`.`UserId` AS `Tickets.UserId`
FROM
`users` AS `User`
LEFT OUTER JOIN
`tickets` AS `Tickets` ON `User`.`id` = `Tickets`.`UserId`;
注意LEFT OUTER JOIN子句的区别.这将引发以下错误:
Unhandled rejection SequelizeDatabaseError: Unknown column 'Tickets.UserId' in 'field list'
我需要一些帮助来找出我在哪里出了问题.
解决方法:
在定义关联时,例如belongsTo,可以指定一个foreignKey和一个targetKey. foreignKey对应于源表中的字段(请记住,语法为sourceModel.belongsTo(targetModel,options)). targetKey对应于目标表中的字段.
就您而言,您在models / ticket.js文件中的关联中犯了一个错误,您使用了:
models.Ticket.belongsTo(models.User, { foreignKey: "createdby" });
在这里,foreignKey引用了源表Ticket.因此,您要告诉Sequelize在Ticket表中使用createdBy字段,在User表中使用默认字段(主键).由于Ticket中不存在createdBy,因此Sequelize会使用默认的情况,即使用Ticket.UserID.
要修复关联(和查询),您需要将自己的belongsTo更新为以下内容:
models.Ticket.belongsTo(models.User, { targetKey: "createdby" });