Why do I have twice the foreign keys using Sequelize - node.js

Question

I'm trying to setup a simple blog application, I have the following schema definition:
Here is User:
module.exports = function(sequelize, DataTypes) {
var User = sequelize.define("User", {
id: {type: DataTypes.BIGINT, autoincrement:true, primaryKey: true},
firstName: {type: DataTypes.STRING},
lastName: {type: DataTypes.STRING},
nickName: {type: DataTypes.STRING},
email: {type: DataTypes.STRING, unique: true, comment: "Unique "},
password: {type: DataTypes.STRING},
salt: {type: DataTypes.STRING},
enabled: {type: DataTypes.BOOLEAN, allowNull: false, defaultValue: true}
}, {
freezeTableName: true,
classMethods: {
associate: function (models) {
User.hasMany(models.Article, {as: "Articles", constraints: false});
User.hasMany(models.Comment, {as: "Comments", constraints: false});
}
}
});
return User;
};
Here is Article:
module.exports = function(sequelize, DataTypes) {
var Article = sequelize.define("Article", {
id: {type: DataTypes.BIGINT, autoincrement:true, primaryKey: true},
slug: {type: DataTypes.STRING, comment: "Unique URL slug to access the article"},
title: {type: DataTypes.STRING},
content: {type: DataTypes.TEXT},
created: {type: DataTypes.DATE, defaultValue: DataTypes.NOW},
published: {type: DataTypes.BOOLEAN, allowNull: false, defaultValue: true}
}, {
freezeTableName: true,
classMethods: {
associate: function (models) {
Article.belongsTo(models.User, {as: "Author", foreignKey: "author_id"});
Article.hasMany(models.Comment, {as: "Comments", constraints: false});
}
}
});
return Article;
};
and Comment:
module.exports = function(sequelize, DataTypes) {
var Comment = sequelize.define("Comment", {
id: {type: DataTypes.BIGINT, autoincrement:true, primaryKey: true},
content: {type: DataTypes.TEXT},
status: {type: DataTypes.INTEGER, defaultValue: 1},
author: {type: DataTypes.BIGINT},
article: {type: DataTypes.BIGINT}
}, {
freezeTableName: true,
classMethods: {
associate: function (models) {
Comment.hasOne(Comment, {as : "Parent", foreignKey: "parent_id"});
Comment.belongsTo(models.User, {as: "Author", foreignKey: "author_id"});
Comment.belongsTo(models.Article, {as: "Article", foreignKey: "article_id"});
}
}
});
return Comment;
};
The tables are created correctly but I end up with 2 foreign keys each time, for instance this is the Article table in MySQL:
'id','bigint(20)','NO','PRI','0',''
'slug','varchar(255)','YES','',NULL,''
'title','varchar(255)','YES','',NULL,''
'content','text','YES','',NULL,''
'created','datetime','YES','',NULL,''
'published','tinyint(1)','NO','','1',''
'createdAt','datetime','NO','',NULL,''
'updatedAt','datetime','NO','',NULL,''
'author_id','bigint(20)','YES','MUL',NULL,''
'UserId','bigint(20)','YES','',NULL,''
UserId == author_id
User Table:
'id','bigint(20)','NO','PRI','0',''
'firstName','varchar(255)','YES','',NULL,''
'lastName','varchar(255)','YES','',NULL,''
'nickName','varchar(255)','YES','',NULL,''
'email','varchar(255)','YES','UNI',NULL,''
'password','varchar(255)','YES','',NULL,''
'salt','varchar(255)','YES','',NULL,''
'enabled','tinyint(1)','NO','','1',''
'createdAt','datetime','NO','',NULL,''
'updatedAt','datetime','NO','',NULL,''
This table is correct (no foreign keys)
Comment:
'id','bigint(20)','NO','PRI','0',''
'content','text','YES','',NULL,''
'status','int(11)','YES','','1',''
'author','bigint(20)','YES','',NULL,''
'article','bigint(20)','YES','',NULL,''
'createdAt','datetime','NO','',NULL,''
'updatedAt','datetime','NO','',NULL,''
'ArticleId','bigint(20)','YES','',NULL,''
'parent_id','bigint(20)','YES','MUL',NULL,''
'author_id','bigint(20)','YES','MUL',NULL,''
'article_id','bigint(20)','YES','MUL',NULL,''
'UserId','bigint(20)','YES','',NULL,''
ArticleId == article_id and UserId == author_id
As you can see I have the version camel cased and the one I've specified. What did I miss?
** EDIT **
There is no constraints in the database for the camel case field: UserId and ArticleId but Sequelize created the fields in the tables.

Answer 1

You need to add the foreign key on both sides of the relation, e.g:
User.hasMany(models.Article, {constraints: false, foreignKey: 'author_id'});