Sequelize find by association through manually-defined join table - node.js

Question

I know that there is a simpler case described here:
Unfortunately, my case is a bit more complex than that. I have a User model which belongsToMany Departments (which in turn belongsToMany Users), but does so through userDepartment, a manually defined join table. My goal is to get all the users belonging to a given department. First let's look at models/user.js:
var user = sequelize.define("user", {
id: {
type: DataTypes.INTEGER,
field: 'emplId',
primaryKey: true,
autoIncrement: false
},
firstname: {
type: DataTypes.STRING,
field: 'firstname_preferred',
defaultValue: '',
allowNull: false
}
...
...
...
associate: function(models) {
user.belongsToMany(models.department, {
foreignKey: "emplId",
through: 'userDepartment'
});
})
}
...
return user;
Now, a look at models/department.js:
var department = sequelize.define("department", {
id: {
type: DataTypes.INTEGER,
field: 'departmentId',
primaryKey: true,
autoIncrement: true
},
...
classMethods: {
associate: function(models) {
department.belongsToMany(models.user, {
foreignKey: "departmentId",
through: 'userDepartment',
onDelete: 'cascade'
});
}
...
return department;
And finally at models/userDepartment.js:
var userDepartment = sequelize.define("userDepartment", {
title: {
type: DataTypes.STRING,
field: 'title',
allowNull: false,
defaultValue: ''
}
}, {
tableName: 'user_departments'
});
return userDepartment;
So far so good. However, this query:
models.user.findAll({
where: {'departments.id': req.params.id},
include: [{model: models.department, as: models.department.tableName}]
})
Fails with the following error:
SequelizeDatabaseError: ER_BAD_FIELD_ERROR: Unknown column 'user.departments.id' in 'where clause'
Attempting to include userDepartment model results in:
Error: userDepartment (user_departments) is not associated to user!
In short: I have two Sequelize Models with a M:M relationship. They are associated through a manually defined join table (which adds a job title to each unique relationship, i.e., User A is a "Manager" in Department B). Attempting to find Users by Department fails with a bad table name error.
sequelize version "^2.0.5"

Answer 1

Took a couple of hours, but I found my solution:
models.department.find({
where: {id:req.params.id},
include: [models.user]
The problem is that Sequelize won't let you "go out of scope" because it begins each where clause with model_name. So, for example, the where clause was trying to compare user.departments.id when the departments table is only joined as departments.id. Since we're querying on a value of the department (the ID), it makes the most since to query for a single department and return their associated users.

Answer 2

I had a similair problem, but in my case I couldn't switch the tables.
I had to make use of the: sequelize.literal function.
In your case it would look like the following:
models.user.findAll({
where: sequelize.literal("departments.id = " + req.params.id),
include: [{model: models.department, as: models.department.tableName}]
})
I'm not fond of it, but it works.

Answer 3

For anyone still looking for an answer for this, I found one here on Github.
You simply do this:
where: {
'$Table.column$' : value
}

Answer 4

You can also use the auto-generated instance.getOthers() method if you have a class instance
This does potentially mean one extra query. But if the instance is already at hand, this is the most convenient syntax.
Supposing a "user likes post with given score" situation, we can get all the posts that a user likes with:
const user0 = await User.create({name: 'user0'})
const user0Likes = await user0.getPosts({order: [['body', 'ASC']]})
assert(user0Likes[0].body === 'post0');
assert(user0Likes[0].UserLikesPost.score === 1);
assert(user0Likes.length === 1);
Full runnable example:
main.js
const assert = require('assert')
const { DataTypes, Op, Sequelize } = require('sequelize')
const common = require('./common')
const sequelize = common.sequelize(__filename, process.argv[2], { define: { timestamps: false } })
;(async () => {
// Create the tables.
const User = sequelize.define('User', {
name: { type: DataTypes.STRING },
});
const Post = sequelize.define('Post', {
body: { type: DataTypes.STRING },
});
const UserLikesPost = sequelize.define('UserLikesPost', {
UserId: {
type: DataTypes.INTEGER,
references: {
model: User,
key: 'id'
}
},
PostId: {
type: DataTypes.INTEGER,
references: {
model: Post,
key: 'id'
}
},
score: {
type: DataTypes.INTEGER,
},
});
User.belongsToMany(Post, {through: UserLikesPost});
Post.belongsToMany(User, {through: UserLikesPost});
await sequelize.sync({force: true});
// Create some users and likes.
const user0 = await User.create({name: 'user0'})
const user1 = await User.create({name: 'user1'})
const user2 = await User.create({name: 'user2'})
const post0 = await Post.create({body: 'post0'});
const post1 = await Post.create({body: 'post1'});
const post2 = await Post.create({body: 'post2'});
// Autogenerated add* methods
// Make some useres like some posts.
await user0.addPost(post0, {through: {score: 1}})
await user1.addPost(post1, {through: {score: 2}})
await user1.addPost(post2, {through: {score: 3}})
// Find what user0 likes.
const user0Likes = await user0.getPosts({order: [['body', 'ASC']]})
assert(user0Likes[0].body === 'post0');
assert(user0Likes[0].UserLikesPost.score === 1);
assert(user0Likes.length === 1);
// Find what user1 likes.
const user1Likes = await user1.getPosts({order: [['body', 'ASC']]})
assert(user1Likes[0].body === 'post1');
assert(user1Likes[0].UserLikesPost.score === 2);
assert(user1Likes[1].body === 'post2');
assert(user1Likes[1].UserLikesPost.score === 3);
assert(user1Likes.length === 2);
// Where on the custom through table column.
// Find posts that user1 likes which have score greater than 2.
// https://stackoverflow.com/questions/38857156/how-to-query-many-to-many-relationship-sequelize
{
const rows = await Post.findAll({
include: [
{
model: User,
where: {id: user1.id},
through: {
where: {score: { [Op.gt]: 2 }},
},
},
],
})
assert.strictEqual(rows[0].body, 'post2');
// TODO how to get the score here as well?
//assert.strictEqual(rows[0].UserLikesPost.score, 3);
assert.strictEqual(rows.length, 1);
}
})().finally(() => { return sequelize.close() });
common.js
const path = require('path');
const { Sequelize } = require('sequelize');
function sequelize(filename, dialect, opts) {
if (dialect === undefined) {
dialect = 'l'
}
if (dialect === 'l') {
return new Sequelize(Object.assign({
dialect: 'sqlite',
storage: path.parse(filename).name + '.sqlite'
}, opts));
} else if (dialect === 'p') {
return new Sequelize('tmp', undefined, undefined, Object.assign({
dialect: 'postgres',
host: '/var/run/postgresql',
}, opts));
} else {
throw new Error('Unknown dialect')
}
}
exports.sequelize = sequelize
package.json
{
"name": "tmp",
"private": true,
"version": "1.0.0",
"dependencies": {
"pg": "8.5.1",
"pg-hstore": "2.3.3",
"sequelize": "6.5.1",
"sqlite3": "5.0.2"
}
}
tested on PostgreSQL 13.4, Ubuntu 21.04.