Sequelize findAll() throwing error when including associations

Question

I'm pretty new to Sequelize and trying to learn all of the cool tricks you can use to format your queries, but have run into a bit of a wall.

Basically, I have a table "invoices". I have another table "invoice_items" which has a relationship of many invoice_items to one invoice.

Currently, I am trying to include this one-to-many association in a findAll query such that the invoice_items are nested in an array in each invoice object.

Something along the lines of:

[
  {
    "name": "invoice1",
    "invoiceItems": ["itemOne", "itemTwo"]
  },
  {
    "name": "invoice2",
    "invoiceItems": ["itemOne", "itemTwo"]
  }
]

When I try this query (essentially grabbed from the documentation):

`db.invoice.findAll({
    where: {
        userId: 'ed8fdd40-b807-4e51-b1f5-90fb5b7f6e73'
    },
    include: { all: true, nested: true }
}).then(result => {
    console.log(result)
})`

I am met with an error

c:\Users\brend\Desktop\projects\invoice-server\node_modules\sequelize\lib\model.js:1189
          let associations = result.get(include.association.as);
                                    ^

TypeError: result.get is not a function
    at c:\Users\brend\Desktop\projects\invoice-server\node_modules\sequelize\lib\model.js:1189:37
    at Array.reduce (<anonymous>)
    at c:\Users\brend\Desktop\projects\invoice-server\node_modules\sequelize\lib\model.js:1188:50
    at Array.map (<anonymous>)
    at Model._findSeparate (c:\Users\brend\Desktop\projects\invoice-server\node_modules\sequelize\lib\model.js:1186:39)
    at invoice.findAll (c:\Users\brend\Desktop\projects\invoice-server\node_modules\sequelize\lib\model.js:1153:24)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)

Node.js v20.10.0

The odd thing is that when I try something like this the query succeeds, but is not formatted as intended (A separate invoice object for each associated invoiceItem)

`db.invoice.findAll({
    where: {
        userId: 'ed8fdd40-b807-4e51-b1f5-90fb5b7f6e73'
    },
    include: "invoiceItems",
    raw : true ,
    nest : true
}).then(result => {
    console.log(result)
})`

To aid in identifying the issue I will add more full code below (wondering if I have the associations messed up):

invoice model

`module.exports = (sequelize, Sequelize, DataType) => {
    const Invoice = sequelize.define('invoice', {
        id: {
         type: DataType.UUID,
         primaryKey: true
        },
        userId: {
         type: DataType.UUID,
         validate: {
            allowNull: false
         }
        },
        name: {
         type: DataType.STRING(150)
        }
//Additional fields left out here for simplicity
     },{
        underscored: true
     });
     Invoice.associate = models => {
      Invoice.hasMany(models.invoiceItem), {
         foreignKey: "invoiceId"
      }
      Invoice.belongsTo(models.user)
     };

     return Invoice
};`

invoiceItem model

`module.exports = (sequelize, Sequelize, DataType) => {
    const InvoiceItem = sequelize.define('invoiceItem', {
        id: {
         type: DataType.UUID,
         primaryKey: true
        },
        invoiceId: {
         type: DataType.UUID,
         validate: {
            allowNull: false
         }
        },
        userId: {
         type: DataType.UUID,
         validate: {
            allowNull: false
         }
        },
        name: {
         type: DataType.STRING(150)
        }
//Additional fields left out here for simplicity
     },{
        underscored: true
     });
     InvoiceItem.associate = models => {
      InvoiceItem.belongsTo(models.invoice, {
         foreignKey: "invoiceId"
      })
      InvoiceItem.belongsTo(models.user), {
         foreignKey: "userId"
      }};

     return InvoiceItem
};`

And finally my index.js file that brings everything together

`'use strict';

const fs = require('fs');
const path = require('path');
const Sequelize = require('sequelize');
const basename = path.basename(__filename);
const sequelize = require('../config/database.js')

const db = {}
db.Sequelize = Sequelize;
db.sequelize = sequelize;

fs.readdirSync(__dirname)
  .filter(file => {
    return (
      file.indexOf('.') !== 0 &&
      file !== basename &&
      file.slice(-3) === '.js' &&
      file.indexOf('.test.js') === -1
    );
  })
  .forEach(file => {
    const model = require(path.join(__dirname, file))(db.sequelize, db.Sequelize, db.Sequelize.DataTypes)
    db[model.name] = model;
  });
Object.keys(db).forEach(modelName => {
  if (db[modelName].associate) {
    db[modelName].associate(db);
  }
});

module.exports = db;`

Any thoughts or suggestions are much appreciated, thanks in advance!

Answer

Your setup appears to be correct so far, and the issue might be coming from the options you have specified (nested: true):

`db.invoice.findAll({
    where: {
        userId: 'ed8fdd40-b807-4e51-b1f5-90fb5b7f6e73'
    },
    include: { all: true, nested: true }
}).then(result => {
    console.log(result)
})`

In the above code, start by removing nested: true. Other options you can look at are plain: true, raw: true, etc.

This answer was originally posted on Stack Overflow. You can find the full discussion here.