Problem setting up Sequelize association - query with 'include' is failing - node.js

Question

I'm new to Sequelize and trying to test if an n:m association I set up between two models, User and Podcast, is working. When I try to run this query, I get some kind of DB error that isn't specific about what's wrong:
User.findOne({
where: { id: id },
include: [{ model: Podcast }]
});
Does anyone know what I'm messing up? I suspect there's something wrong in how I've set up the association, like I'm referencing the names of tables slightly incorrectly, but the migration to create the association worked.
Here's my User.js model file:
module.exports = (sequelize, DataTypes) => {
const User = sequelize.define('User', {
name: {
type: DataTypes.STRING,
allowNull: false
},
email: {
type: DataTypes.STRING,
allowNull: false,
unique: true
},
photo: {
type: DataTypes.STRING
}
});
User.associate = function(models) {
// associations can be defined here
User.belongsToMany(models.Podcast, {
through: 'user_podcast'
});
};
return User;
};
And here's my Podcast.js file:
'use strict';
module.exports = (sequelize, DataTypes) => {
const Podcast = sequelize.define('Podcast', {
id: {
type: DataTypes.STRING,
primaryKey: true,
allowNull: false
},
title: {
type: DataTypes.STRING,
allowNull: false
},
thumbnail: {
type: DataTypes.STRING
},
website: {
type: DataTypes.STRING
}
});
Podcast.associate = function(models) {
// associations can be defined here
Podcast.belongsToMany(models.User, {
through: 'user_podcast'
});
};
return Podcast;
};
And here's the migration I ran to join the two tables:
'use strict';
module.exports = {
up: function(queryInterface, Sequelize) {
return queryInterface.createTable('user_podcast', {
id: {
allowNull: false,
autoIncrement: true,
primaryKey: true,
type: Sequelize.INTEGER
},
userId: {
type: Sequelize.INTEGER,
references: {
model: 'Users',
key: 'id'
}
},
podcastId: {
type: Sequelize.STRING,
references: {
model: 'Podcasts',
key: 'id'
}
},
createdAt: {
allowNull: false,
type: Sequelize.DATE
},
updatedAt: {
allowNull: false,
type: Sequelize.DATE
}
});
},
down: function(queryInterface, Sequelize) {
return queryInterface.dropTable('user_podcast');
}
};
And here's the project on Github for further reference:
https://github.com/olliebeannn/chatterpod

Answer 1

You don't need to create a migration for the M:N table. Now you have something wrong on your user_podcast model. If you are setting a M:N relation between to tables your primary key will be the combination between the foreign key from these two models. If you still want a single id primary key for your table, then you won't use belongsToMany instead use hasMany on user and podcast models pointing to a new model user_podcast.
As far as I see on your first query, it seems that you really need a M:N relation so you can define the model as you do with user and podcast like this:
module.exports = (sequelize, DataTypes) => {
const UserPodcast = sequelize.define('user_podcast', {
userId: {
// field: 'user_id', #Use 'field' attribute is you have to match a different format name on the db
type: DataTypes.INTEGER
},
podcastId: {
// field: 'podcast_id',
type: DataTypes.INTEGER
},
});
UserPodcast.associate = function(models) {
models.User.belongsToMany(models.Podcast, {
as: 'podcasts', //this is very important
through: { model: UserPodcast },
// foreignKey: 'user_id'
});
models.Podcast.belongsToMany(models.User, {
as: 'users',
through: { model: UserPodcast },
// foreignKey: 'podcast_id'
});
};
return UserPodcast;
};
I do prefer to have the belongsToMany associations on the save function where I define the join model, and you have to notice that I used as: attribute on the association. This is very important because this will help sequelize to know which association are you referring on the query.
User.findOne({
where: { id: id },
include: [{
model: Podcast,
as: 'podcasts' //here I use the previous alias
}]
});