How to add associations to Models generated from Sequelize-Auto

Question

For an existing MySQL database, I used Sequelize-auto package to generate the models. But the associations don't come with model classes.

I have an MySQL database and I'm using it for NodeJS web project. Also I'm using Sequelize as the ORM. Since database is already there I wanted to generate the model classes as the entities. So I used sequelize-auto

https://github.com/sequelize/sequelize-auto to generate the model classes. But when they were generated attributes have been correctly set but the associations doesn't come up with the model classes. So I have faced problem when fetching the data from the database.

Here are the two model classes that were generated with sequlize-auto. There are two table in the database named as department and category. department.js and category.js are the two model classes that were generated

department.js

module.exports = function(sequelize, DataTypes) {
  return sequelize.define('department', {
        department_id: {
            type: DataTypes.INTEGER(11),
            allowNull: false,
            primaryKey: true,
            autoIncrement: true
        },
        name: {
            type: DataTypes.STRING(100),
            allowNull: false
        },
        description: {
            type: DataTypes.STRING(1000),
            allowNull: true
        }
    }, {
        tableName: 'department',
        timestamps: false,
    });
};

category.js

module.exports = function(sequelize, DataTypes) {
  return sequelize.define('category', {
        category_id: {
            type: DataTypes.INTEGER(11),
            allowNull: false,
            primaryKey: true,
            autoIncrement: true
        },
        department_id: {
            type: DataTypes.INTEGER(11),
            allowNull: false
        },
        name: {
            type: DataTypes.STRING(100),
            allowNull: false
        },
        description: {
            type: DataTypes.STRING(1000),
            allowNull: true
        }
    }, {
        tableName: 'category',
        timestamps: false,
    });
};

So what else needs to be done in order to get the associations and to fetch data successfully. Can some one help me here. Table structure is as following.

Answer 1

I followed the pattern demonstrated in the typescript example on sequelize-auto (init-models.ts) - within the existing initModels function, works fine in js.

export function initModels(sequelize: Sequelize) {
  Product.initModel(sequelize);
  Supplier.initModel(sequelize);
  
  Supplier.hasMany(Product, { as: "products", foreignKey: "supplierId"});
  
  return {...

Answer 2

To add to @CodingLittles answer which he based from here.

I added the following for making many to many assosiations:

enum Junctions {
  user = 'user',
  roles = 'roles',
}

enum JuntiontThrough {
  userroles = 'userroles',
}


interface JunctionObject {
  junctionBelongsTo?: any;
}

const checkIfAttrExists= (obj, value) => {
  return Object.prototype.hasOwnProperty.call(obj, value);
};

const checkRefrence = (obj, attr, value) => {
  return obj.rawAttributes[attr].references[value];
};


export const getJunction = (junc: Junctions): JunctionObject => {
  const junctions = {
    user: {
      junctionBelongsTo: [
        { key: Junctions.roles, value: juntiontThrough.userroles }
      ],
    },
    roles: {
      junctionBelongsTo: [{ key: Junctions.user, value: juntiontThrough.userroles }],
    },
  }[junc];

  if (!junctions) return {};

  return junctions;
};


  const models = Object.getOwnPropertyNames(db);

models.forEach(modelName => {
  const currentModel = db[modelName];
  const junction = getJunction(modelName as Junctions);

  if (!_.isEmpty(junction)) {
    // eslint-disable-next-line array-callback-return
    junction.junctionBelongsTo.reduce((key, value) => {
      currentModel.belongsToMany(db[value.key], {
        through: db[value.value],
      });
    }, {});
  }

  const attributes = Object.getOwnPropertyNames(currentModel.rawAttributes);

  attributes.forEach(attributeName => {
    if (
      checkIfAttrExists(currentModel.rawAttributes[attributeName], 'references') &&
      checkIfAttrExists(currentModel.rawAttributes[attributeName].references, 'model') &&
      checkIfAttrExists(currentModel.rawAttributes[attributeName].references, 'key')
    ) {
      if (
        !(
          checkRefrence(currentModel, attributeName, 'model') &&
          checkRefrence(currentModel, attributeName, 'key')
        )
      ) {
        return;
      }

      const referencedTable =
        tableModel[currentModel.rawAttributes[attributeName].references.model];

      if (!(modelName.toString() in juntiontThrough)) {
        console.log(
          `${modelName} ${attributeName} references a model ${currentModel.rawAttributes[attributeName].references.model} with key ${currentModel.rawAttributes[attributeName].references.key}`
        );
        currentModel.belongsTo(referencedTable, { foreignKey: attributeName });
        referencedTable.hasMany(currentModel, { foreignKey: attributeName });
      }
    }
  });
})

Note that for the many to many relations to work you have to add the relations manually like I did in the getJunction function

Answer 3

1) inside of your models folder create an index.js file and add the following code

import Sequelize from 'sequelize';

const fs = require('fs');
const path = require('path');

const basename = path.basename(__filename);

const db = {};

// @ts-ignore
const sequelize = new Sequelize('dbname', 'dbUser', 'password', {
  host: '127.0.0.1',
  port: 'PORT',
  dialect: 'mysql',
  define: {
    freezeTableName: true,
    timestamps: false,
  },
  pool: {
    max: 5,
    min: 0,
    acquire: 30000,
    idle: 10000,
  },
  // <http://docs.sequelizejs.com/manual/tutorial/querying.html#operators>
  operatorsAliases: false,
});

const tableModel = {};

fs.readdirSync(__dirname)
  .filter(file => file.indexOf('.') !== 0 && file !== basename && file.slice(-3) === '.js')
  .forEach(file => {
    const model = sequelize.import(path.join(__dirname, file));
    db[model.name] = model;
    tableModel[model.name] = model;
  });

Object.getOwnPropertyNames(db).forEach(modelName => {
  const currentModel = db[modelName];
  Object.getOwnPropertyNames(currentModel.rawAttributes).forEach(attributeName => {
    if (
      Object.prototype.hasOwnProperty.call(
        currentModel.rawAttributes[attributeName],
        'references'
      ) &&
      Object.prototype.hasOwnProperty.call(
        currentModel.rawAttributes[attributeName].references,
        'model'
      ) &&
      Object.prototype.hasOwnProperty.call(
        currentModel.rawAttributes[attributeName].references,
        'key'
      )
    ) {
      if (
        !(
          currentModel.rawAttributes[attributeName].references.model &&
          currentModel.rawAttributes[attributeName].references.key
        )
      ) {
        console.log(
          `*SKIPPED* ${modelName} ${attributeName} references a model ${currentModel.rawAttributes[attributeName].references.model} with key ${currentModel.rawAttributes[attributeName].references.key}`
        );
        return;
      }

      console.log(
        `${modelName} ${attributeName} references a model ${currentModel.rawAttributes[attributeName].references.model} with key ${currentModel.rawAttributes[attributeName].references.key}`
      );
      const referencedTable =
        tableModel[currentModel.rawAttributes[attributeName].references.model];

      currentModel.belongsTo(referencedTable, { foreignKey: attributeName });
      referencedTable.hasMany(currentModel, { foreignKey: attributeName });

    }
  });
});

// @ts-ignore
db.sequelize = sequelize;
// @ts-ignore
db.Sequelize = Sequelize;

// eslint-disable-next-line eol-last
module.exports = db;

2) inside of your resolver just reference the above:

const db = require('../assets/models/index');