Sequelize associate not creating foreign key - mysql

Question

According to sequelize documentation, Model.hasMany should automatically create foreign key references with constraints. But when i try it in my code it does not. I have to manually add the foreign key to the migration. Please how can i fix this? This is my User model
'use strict';
module.exports = (sequelize, DataTypes) => {
const User = sequelize.define('User', {
name: DataTypes.STRING,
username: DataTypes.STRING,
email: DataTypes.STRING,
password: DataTypes.STRING
});
User.associate = function(models) {
// associations can be defined here
User.hasMany(models.Post);
};
return User;
};
and this is my post model
'use strict';
module.exports = (sequelize, DataTypes) => {
const Post = sequelize.define('Post', {
title: DataTypes.STRING,
body: DataTypes.TEXT
});
Post.associate = function(models) {
Post.belongsTo(models.User);
};
return Post;
};

Answer 1

To create foreign key, you'll need to put the information of which column is the primary key and the foreign key referred:
'use strict';
module.exports = (sequelize, DataTypes) => {
const User = sequelize.define('User', {
name: {
DataTypes.STRING,
primaryKey: true
},
username: DataTypes.STRING,
email: DataTypes.STRING,
password: DataTypes.STRING
});
User.associate = function(models) {
// associations can be defined here
User.hasMany(models.Post, {
foreignKey: modelId
);
};
return User;
};
Note that, in your User, I defined which column is the primary key and, in hasMany, I defined which column on Post is the foreignKey.

Answer 2

After much struggle with this I finally figured it out.
The db:migrate command uses the migration files and does not include the model files.
To use the model files instead, I just needed to do this in the app.js file
...
...
const db = require('./models');
db.sequelize.init();
Although a lot of experience programmers do not recommend this method. They suggest that the best method is manually creating the foreign key in the migration files.