Sequelize associations not being created in MySQL, PostgreSQL and SQLite - mysql

Question

I am defining associations in models using sequalize with MYSQL. But after migration, the foreign key is not being added to the target model as explained in sequelize docs.
I have also tried to manually define foreign keys in models and migration files but still no association is being created between tables. When I view the tables in relation view in PhpMyAdmin, not foreign key constraints or relationship is being created.
I have tried this with SQLite, and PostgreSQL with the same results. I don't know what I am doing wrong. Here are models.
AURHOR MODEL
//One author hasMany books
'use strict';
module.exports = (sequelize, DataTypes) => {
const Author = sequelize.define('Author', {
Name: DataTypes.STRING
}, {});
Author.associate = function(models) {
// associations can be defined here
Author.hasMany(models.Book)
};
return Author;
};
I expect sequelize to add authorId on books table as specified in the docs, but this not happening
BOOK MODEL
//Book belongs to Author
'use strict';
module.exports = (sequelize, DataTypes) => {
const Book = sequelize.define('Book', {
Title: DataTypes.STRING
}, {});
Book.associate = function(models) {
// associations can be defined here
Book.belongsTo(models.Author)
};
return Book;
};
No associations is being created between these two tables after migration.
I have as well tried to define custom foreign keys in model associations like this:
//Author model
Author.hasMany(models.Book,{foreignKey:'AuthorId'})
//Book model
Book.belongsTo(models.Author,{foreignKey:'AuthorId'})
still this not solving the problem
I have gone ahead to define foreign keys in models then referencing them in the association like this:
'use strict';
module.exports = (sequelize, DataTypes) => {
const Book = sequelize.define('Book', {
Title: DataTypes.STRING,
AuthorId:DataTypes.INTEGER
}, {});
Book.associate = function(models) {
// associations can be defined here
Book.belongsTo(models.Author,{foreignKey:'AuthorId'})
};
return Book;
};
But still no associations is being created
I finally decided to add references in migration files like so:
'use strict';
module.exports = {
up: (queryInterface, Sequelize) => {
return queryInterface.createTable('Books', {
id: {
allowNull: false,
autoIncrement: true,
primaryKey: true,
type: Sequelize.INTEGER
},
Title: {
type: Sequelize.STRING
},
AuthorId:{
type: Sequelize.INTEGER,
references:{
model:'Author',
key:'id'
}
}
createdAt: {
allowNull: false,
type: Sequelize.DATE
},
updatedAt: {
allowNull: false,
type: Sequelize.DATE
}
});
},
down: (queryInterface, Sequelize) => {
return queryInterface.dropTable('Books');
}
};
But when I run this kind of migration setup, I get this error: ERROR: Can't create table dbname.books (errno: 150 "Foreign key constraint is i
ncorrectly formed")
I get similar error when I switch to PostgreSQL.
I have been held back by this issue for quite long. What may I doing wrong. I am using sequelize version 4.31.2 with sequelize CLI.

Answer 1

I was referencing to models wrongly in migrations.
Wrong way
AuthorId:{
type: Sequelize.INTEGER,
references:{
model:'Author',
key:'id'
}
}
Correct Way
// Notes the model value is in lower case and plural just like the table name in the database
AuthorId:{
type: Sequelize.INTEGER,
references:{
**model:'authors',**
key:'id'
}
}
This solved my problem. The associations is now getting defined.