Sequelize - ForeignKey relationship - problem with alias

问题

I have two tables. One is skills, another is ratings. My problem is specific to ratings: The model of ratings is:

var sequelize = require('../sequelizeConfig');
var Sequelize = require('sequelize');

var Ratings=sequelize.define('ratings',{
  ratingID:{
     type:Sequelize.BIGINT,
     field:'rating_id',
     primaryKey:true
  },
   empID:{
       type: Sequelize.STRING,
       field:'emp_id'
    },
   skillID:{
       type:Sequelize.STRING,
       field:'skill_id',
       references: {
        model: 'skills',
        key: 'skill_id'
       }
    },
   rating:{
    type: Sequelize.BIGINT ,
  field:'rating'  
}
},{
    tableName:'ratings',
    freezeTableName: true 
  })

module.exports=Ratings;

In controller, i have below relation. I am unsure if use of hasOne is right. With only 'belongsTo' to state foreignkey relationship, i only got ratings is not associated to skills. Basically skill_id in ratings table has reference to skill_id in skills table.

var skillsets = require('../../models/skillsets');
var ratings = require('../../models/ratings');
skillsets.hasOne(ratings,{foreignKey:'skillID',sourceKey:'skillsetID'});
ratings.belongsTo(skillsets,{foreignKey:'skillID',targetKey:'skillsetID'});

I tried to query as below:

skillsets.findAll({
            where:{
                roleID: role
            },
            include:[{
                model:ratings,
                where:{
                    emp_id: empID
                },
                attributes:['rating'],
                required:false
            }]
        })

Everything seem fine but this hasOne does something fishy. It generates query as:

SELECT "skills"."skill_id" AS "skillsetID", "skills"."role_id" AS "roleID", "skills"."field", "skills"."skill_name" AS "skillName", "rating"."rating_id" AS "rating.ratingID", "rating"."rating" AS "rating.rating" FROM "skills" AS "skills" LEFT OUTER JOIN "ratings" AS "rating" ON "skills"."skill_id" = "rating"."skill_id" AND "rating"."emp_id" = '12344' WHERE "skills"."role_id" = 'developer';

Due to "rating"."rating" AS "rating.rating" , result comes as below:

[
    {
        "skillsetID": "Angular",
        "roleID": "developer",
        "field": "Frontend",
        "skillName": "Angular",
        "rating": 
            {
                "rating": "4"
            }

}]

What i expect is just like:

  [
        {
            "skillsetID": "Angular",
            "roleID": "developer",
            "field": "Frontend",
            "skillName": "Angular",
            "rating":4
    }]

Could you please favour?

回答1:

This nesting of included model ratings is the default behavior in sequelize. You can pass in the option raw: true to get a result that looks like this:

{
    "skillsetID": "Angular",
    "roleID": "developer",
    "field": "Frontend",
    "skillName": "Angular",
    "rating.rating": "4",
}

If you don't want the dot notation in the keys then you can change your sequelize query like this:

var sequelize = require('../sequelizeConfig'); 

skillsets.findAll({
    attributes: {
        include: [ // Include these attributes along with all other attributes
            [
                sequelize.literal('rating.rating'), // get `rating` from `ratings` table in the query
                'rating', // use `rating` as alias
            ]
        ]
    },
    where: {
        roleID: role
    },
    include: [
        {
            model: ratings,
            where: {
                emp_id: empID
            },
            attributes: [], // This tells sequelize to not nest any attributes inside ratings object
            required: false
        }
    ]
});

This will give you the required result:

{
    "skillsetID": "Angular",
    "roleID": "developer",
    "field": "Frontend",
    "skillName": "Angular",
    "rating": "4",
}

hasOne and belongsTo: The purpose of relations in sequelize is that they allow you to include related models when querying and make relations when creating tables. If you don't add a hasOne relation. Then sequelize will tell you that skills does not belong to rating even if there is a foreign key skillID inside the ratings table. hasOne tells sequelize that you can include the model ratings inside skills with a 1-1 relationship

来源：https://stackoverflow.com/questions/59107738/sequelize-foreignkey-relationship-problem-with-alias