CODEWITHSUNDEEP
node.jsapirestexpresssequelize.js
Fred
Fred

Reputation: 202

BelongsToMany Relationship - Sequelize

I have a problem in the listing of records with belongsToMany association using sequelize + nodejs.

I have the developers and technologies tables. The relationship between them is many to many. To create a relationship, use a pivot table called developers_technologies.

Below is a gist with the code of: Models (developers, technologies), migration (developers_technologies) and controller of Developers.

https://gist.github.com/fredarend/85ff60fca70643d80301b499e871c4a6

The code of the Index of the controller Developer is this:

async index(req, res) {
const developers = await Developer.findAll({
  attributes: ['id', 'name', 'email'],
  include: [
    {
      model: Technologies,
      as: 'technologies',
      attributes: ['id', 'name'],
      through: { attributes: [] },
    },
  ],
});

return res.json(developers);}

Return:

[
    {
        "id": 25,
        "name": "Jon Doe",
        "email": "[email protected]",
        "age": 27,
        "url_linkedin": "http://asdasdasd",
        "technologies": []
    }
]

I would like to know why I am not receiving technologies linked to the developer, since the developers_technologies table in the database is populated and the relationships in the models are ok.

EDIT: query generated from the request:

SELECT 
"Developer"."id", 
"Developer"."name", 
"Developer"."email", 
"technologies"."id" AS "technologies.id", 
"technologies"."name" AS "technologies.name", 
"technologies->developers_technologies"."created_at" AS "technologies.developers_technologies.createdAt", 
"technologies->developers_technologies"."updated_at" AS "technologies.developers_technologies.updatedAt", 
"technologies->developers_technologies"."developer_id" AS "technologies.developers_technologies.developer_id", 
"technologies->developers_technologies"."technology_id" AS "technologies.developers_technologies.technology_id" 
FROM "developers" AS "Developer" 
LEFT OUTER JOIN ( "developers_technologies" AS "technologies->developers_technologies" 
INNER JOIN "technologies" AS "technologies" ON "technologies"."id" = "technologies->developers_technologies"."developer_id") ON "Developer"."id" = "technologies->developers_technologies"."technology_id";

Kind regards,

Upvotes: 0

Views: 1140

Answers (1)

Anatoly
Anatoly

Reputation: 22758

Try to indicate otherKey in belongToMany associations. Also you indicated wrong foreign keys. For Developer it should be developer_id and for Technology it should be technology_id:

Model - Developer

this.belongsToMany(models.Technology, {
      foreignKey: 'developer_id',
      otherKey: 'technology_id',
      through: 'developers_technologies',
      as: 'technologies',
    });

Model - Technology

this.belongsToMany(models.Developer, {
      foreignKey: 'technology_id',
      otherKey: 'developer_id',
      through: 'developers_technologies',
      as: 'developers',
    });

Upvotes: 2

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