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),field: "username"
},fullname: {
type: DataTypes.STRING(60),field: "fullname"
},createdat: {
type: DataTypes.DATE,field: "createdat"
},updateat: {
type: DataTypes.DATE,allowNull: true,field: "updateat"
},deletedat: {
type: DataTypes.DATE,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",details: {
type: DataTypes.STRING(45),field: "details"
},assignedto: {
type: DataTypes.INTEGER(11),field: "assignedto"
},createdby: {
type: DataTypes.INTEGER(11),field: "createdby"
},updatedat: {
type: DataTypes.DATE,field: "updatedat"
},{
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`,`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.
最佳答案
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" });
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