Sequelize association table group - node.js

Question

I have two tables medforms and category each medform can have multiple categories. for multiple categories, I made another association table medform_categories.
'use strict';
const {
Model
} = require('sequelize');
module.exports = (sequelize, DataTypes) => {
class MedForm extends Model {
/**
* Helper method for defining associations.
* This method is not a part of Sequelize lifecycle.
* The `models/index` file will call this method automatically.
*/
static associate(models) {
// define association here
}
};
MedForm.init({
med_id: {
type: DataTypes.INTEGER,
primaryKey: true,
autoIncrement: true
},
med_name: {
type: DataTypes.STRING,
allowNull: false
},
}, {
sequelize,
modelName: 'medforms',
});
MedForm.associate = function (models) {
MedForm.hasMany(models.medforms_category, {
foreignKey: 'med_id',
as: 'medform'
});
};
return MedForm;
};
category table schema:
'use strict';
const {
Model
} = require('sequelize');
module.exports = (sequelize, DataTypes) => {
class Category extends Model {
static associate(models) {
}
};
Category.init({
category_id: {
allowNull: false,
autoIncrement: true,
primaryKey: true,
type: DataTypes.INTEGER
},
category_name: {
type: DataTypes.STRING,
},
}, {
sequelize,
modelName: 'categories',
});
Category.associate = function (models) {
Category.hasMany(models.medforms_category, {
foreignKey: 'category_id',
as: 'category'
});
};
return Category;
};
and finally the association table medform_category
'use strict';
const {
Model
} = require('sequelize');
module.exports = (sequelize, DataTypes) => {
class Medform_categories extends Model {
static associate(models) {
}
};
Medform_categories.init({
medform_category_id: {
type: DataTypes.INTEGER,
primaryKey: true,
autoIncrement: true
},
category_id: {
type: DataTypes.INTEGER,
references: {
model: 'categories',
key: 'category_id'
},
onUpdate: 'CASCADE',
onDelete: 'CASCADE'
},
med_id: {
type: DataTypes.INTEGER,
allowNull: false,
references: {
model: 'medforms',
key: 'med_id'
},
onUpdate: 'CASCADE',
onDelete: 'CASCADE'
},
}, {
sequelize,
modelName: 'medform_categories',
});
Medform_categories.associate = function (models) {
Medform_categories.belongsTo(models.medforms, {
foreignKey: 'med_id',
as: 'medform'
});
Medform_categories.belongsTo(models.categories, {
foreignKey: 'category_id',
as: 'category'
});
};
return Medform_categories;
};
now I want data like:
"category": [
{
"category_id": 1,
"category_name": "cat1",
"medforms": {
"med_id": 1,
"med_name": "Mobilfunk 1",
"med_fullname": "Mobilfunk 1",
},
{
"med_id": 2,
"med_name": "Mobilfunk 2",
"med_fullname": "Mobilfunk 2",
}
},
{
"category_id": 2,
"category_name": "cat2",
"medforms": {
"med_id": 1,
"med_name": "Mobilfunk 1",
"med_fullname": "Mobilfunk 1",
},
{
"med_id": 3,
"med_name": "Mobilfunk 3",
"med_fullname": "Mobilfunk 3",
}
},
]
can some one please help me here? what I should do here? Inside the
controller to fetch data like mentioned above?
const db = require("../models");
const Categories = db.categories; // tables db instance
// Retrieve all objects (with include)
exports.getAllCategories = (req, res) => {
Categories.findAll({
include: [
{
model: db.medforms_category,
as: 'category',
include: [
{
model: db.medforms,
as: 'medform',
}]
},
],
})
.then(data => {
res.send(data);
})
.catch(err => {
res.status(500).send({
message:
err.message || "Some error occurred while retrieving all data."
});
});
};

Answer 1

If you have a N:N relation, you not necessarely need to have a Model to represent this table.
// Medforms
// ...
static associate(models) {
this.belongsToMany(models.categories, { through: 'medform_categories' });
}
// Categories
// ...
static associate(models) {
this.belongsToMany(models.medforms, { through: 'medform_categories' });
}
// Query will be something like
const categories = await Categories.findAll({
where: {...},
include: ['medforms']
})
const medforms = await Medforms.findAll({
where: {...},
include: ['categories']
})