How to include model in belongstToMany relation in Sequelize - mysql

Question

I want to add in my sequelize query model, but i don't know how to do this correctly.
I have two tables: Regions and Countries. There is a relation between them called belongsToMany that is going through the table region_countries, there i have foreign keys region_id and country_id. For Region and Countries i have table with translation, for example: table translate_trgions has region and language_code name (en, fr, ru, etc.). And i am getting list of regions with countries with their translations.
My Region model
class Region extends Model {}
Region.init(
{
id: {
type: DataTypes.INTEGER,
primaryKey: true,
autoIncrement: true,
},
},
{ sequelize, timestamps: false, tableName: 'regions', modelName: 'Region' }
);
class RegionTranslate extends Model {}
RegionTranslate.init(
{
id: {
type: DataTypes.INTEGER,
primaryKey: true,
autoIncrement: true,
},
name: {
type: DataTypes.STRING,
allowNull: true,
},
region_id: {
type: DataTypes.INTEGER.UNSIGNED,
references: {
model: Region,
key: 'id',
},
},
language_code: {
type: DataTypes.INTEGER.UNSIGNED,
references: {
model: Language,
key: 'code',
},
},
},
{
sequelize,
timestamps: false,
tableName: 'regions_description',
modelName: 'RegionTranslate',
}
);
class RegionsCountries extends Model {}
RegionsCountries.init(
{
id: {
type: DataTypes.INTEGER,
primaryKey: true,
autoIncrement: true,
},
region_id: {
type: DataTypes.INTEGER.UNSIGNED,
references: {
model: Region,
key: 'id',
},
},
country_id: {
type: DataTypes.INTEGER.UNSIGNED,
references: {
model: Country,
key: 'id',
},
},
},
{
sequelize,
timestamps: false,
tableName: 'region_countries',
modelName: 'RegionsCountries',
}
);
Region.hasMany(RegionTranslate, {
foreignKey: 'region_id',
as: 'translate_regions',
});
RegionTranslate.belongsTo(Region, { foreignKey: 'region_id' });
Region.belongsToMany(Country, {
through: RegionsCountries,
foreignKey: 'region_id',
});
Country.belongsToMany(Region, {
through: RegionsCountries,
foreignKey: 'country_id',
});
Region.belongsToMany(CountryTranslate, {
through: RegionsCountries,
as: 'translate_countries',
foreignKey: 'country_id',
otherKey: 'id',
});
My Country Model
class Country extends Model {}
Country.init(
{
id: {
type: DataTypes.INTEGER,
primaryKey: true,
autoIncrement: true,
},
code: {
type: DataTypes.STRING,
allowNull: false,
},
unicode: {
type: DataTypes.INTEGER,
allowNull: false,
},
},
{ sequelize, timestamps: false, tableName: 'countries', modelName: 'Country' }
);
class CountryTranslate extends Model {}
CountryTranslate.init(
{
id: {
type: DataTypes.INTEGER,
primaryKey: true,
autoIncrement: true,
},
language_code: {
type: DataTypes.INTEGER,
allowNull: false,
references: {
model: Language,
key: 'code',
},
},
country_id: {
type: DataTypes.INTEGER,
allowNull: false,
references: {
model: Country,
key: 'id',
},
},
name: {
type: DataTypes.BOOLEAN,
allowNull: true,
},
description: {
type: DataTypes.BOOLEAN,
allowNull: true,
},
},
{
sequelize,
timestamps: false,
tableName: 'countries_description',
modelName: 'CountryTranslate',
}
);
Country.hasMany(CountryTranslate, {
foreignKey: 'country_id',
as: 'translate_countries',
});
CountryTranslate.belongsTo(Country, { foreignKey: 'country_id' });
Country.belongsToMany(Region, {
through: RegionsCountries,
foreignKey: 'country_id',
});
My query in RegionController
const regions = await Region.findAll({
attributes: {
include: [[Sequelize.literal('translate_regions.name'), 'name']],
},
include: [
{
model: Country,
attributes: {
include: [[Sequelize.literal('translate_countries.name'), 'name']],
},
through: {
attributes: [],
},
},
{
model: RegionTranslate,
as: 'translate_regions',
where: { language_code: language },
attributes: [],
},
{
model: CountryTranslate,
as: 'translate_countries',
},
],
});
The output i'm getting
"regions": [
{
"id": 4,
"name": "Europe",
"Countries": [
{
"id": 3,
"code": "dza",
"unicode": "12",
"name": "Ангола"
}
],
"translate_countries": [
{
"id": 10,
"language_code": "ru",
"country_id": 5,
"name": "Ангола",
"description": null,
"RegionsCountries": {
"id": 10,
"region_id": 4,
"country_id": 4
}
}
]
}
]
The output that i want
"regions": [
{
"id": 4,
"name": "Europe",
"Countries": [
{
"id": 4,
"code": "and",
"unicode": "20",
"name": "Andorra"
}
]
}
]

Answer 1

When setting up your Model associations for many-to-many through a relational table, you need to specify the columns in the relational table that is the foreign key for your source table primary key, as well as the column that is the "other" foreign key for the related table primary key. It's helpful to specify an as property as well to identify the relationship.
This is an example, check other relationships as well.
// use otherKey to indicate the relationship
// country.id -> country_id, region_id -> region.id
Country.belongsToMany(Region, {
as: 'regions',
through: RegionsCountries,
foreignKey: 'country_id',
otherKey: 'region_id'
});
When you query for related records we can no specify the through and as property on the query.
Country.findByPk(countryId, {
include: [{
model: Region,
through: RegionsCountries,
as: 'regions',
}],
});