Custom joins with Sequelize.literal
  • 10-May-2023
Lightrun Team
Author Lightrun Team
Custom joins with Sequelize.literal

Custom joins with Sequelize.literal

Lightrun Team
Lightrun Team

Explanation of the problem

The issue at hand pertains to the inability to define custom joins in Sequelize without explicitly setting up associations between models. Unlike other ORMs such as Rails’ active record, Sequelize lacks the flexibility to perform custom joins for reports or tables when there is no predefined association between the models. The provided example demonstrates the desired functionality using Sequelize.literal(), but currently, it requires the existence of a user to user_report association, which is not always feasible or convenient to define.


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Problem solution for Custom joins with Sequelize.literal

The proposed solution involves enhancing Sequelize to allow the usage of a completely custom Sequelize.literal() expression within the include statement. This would enable developers to specify custom joins using raw SQL queries, such as INNER JOIN user_report reports ON = reports.user_id, without the need for predefined associations. This approach aligns with how other popular ORMs handle custom joins and would be beneficial for users transitioning from frameworks like Rails, Django, and Laravel to Node.js with Sequelize. Several Stack Overflow questions and GitHub issues related to Sequelize highlight the demand for this feature.

As for alternatives or workarounds, the only viable option identified by the user is to resort to raw queries, which negates the convenience and abstraction provided by an ORM like Sequelize. By allowing custom Sequelize.literal() expressions within the include statement, developers would have a more elegant and seamless solution to perform custom joins without relying on associations or falling back to raw queries.

Regarding the Issue Template Checklist, this issue is not dialect-specific and applies to Sequelize as a whole. The user expresses willingness to resolve the issue by submitting a pull request but indicates the need for guidance on how to start.

Other popular problems with Sequelize Sequelize

Problem: Circular Dependency Issues

One of the most common problems when using Sequelize is dealing with circular dependencies between models. This occurs when two or more models reference each other directly, causing a conflict in the association process. This can lead to unpredictable results and errors when trying to access the related data.


The solution to this problem is to carefully design your data models and relationships, taking into account the potential for circular dependencies. This often involves using a mix of associations, such as belongsTo and hasMany, to break the circular relationship. In addition, it may be necessary to split larger models into smaller, more manageable components to reduce the risk of circular dependencies.

Problem: Performance Issues

Performance is another common issue when working with Sequelize. This can occur when complex queries or operations are executed, causing the application to slow down or become unresponsive. This can also occur when working with large datasets, as Sequelize may not be optimized for these types of use cases.


To address performance issues, it is important to regularly monitor and optimize your queries and operations. This may involve using indexing, caching, and other techniques to reduce the load on the database. In addition, you can also consider using alternative ORMs that are specifically designed for performance and scalability, such as TypeORM or Prisma.

Problem: Inconsistent Naming Conventions

Inconsistent naming conventions can also be a problem when using Sequelize. This can occur when using different naming conventions for different parts of your application, such as for tables, columns, and relationships. This can lead to confusion and errors when trying to access and manipulate data, as well as making it more difficult to maintain your code over time.


To resolve this issue, it is recommended to establish and maintain a consistent naming convention throughout your application. This can be done by using a linter or other tool to enforce your naming standards, as well as by documenting your naming conventions for reference. In addition, you can also consider using a tool like Sequelize Auto to automatically generate your models based on your database schema, helping to ensure consistency in your naming conventions.

A brief introduction to Sequelize Sequelize

Sequelize is a popular Object Relational Mapping (ORM) library for Node.js that enables developers to interact with relational databases such as MySQL, PostgreSQL, and SQLite, in a more programmatic way. By using Sequelize, developers can write database logic in their code as opposed to writing raw SQL queries. This allows for a more maintainable and scalable codebase, as well as improved database performance by utilizing the caching and query optimization capabilities of the ORM.

Sequelize provides an extensive set of features including model definition, query generation, transaction management, and association management between tables. With Sequelize, developers can define the structure of their database tables as well as the relationships between tables. This makes it easy to interact with the database, as Sequelize handles the conversion between the relational database data and the JavaScript objects in the application. Additionally, Sequelize provides a powerful query API that allows developers to perform complex database operations with ease, as well as supporting transaction management, which is crucial for ensuring data integrity.

Most popular use cases for Sequelize Sequelize

1. Database Interaction: Sequelize is an ORM (Object Relational Mapping) tool that can be used to interact with a variety of relational databases, such as MySQL, PostgreSQL, and SQLite. The following code demonstrates how to set up a simple connection to a MySQL database and define a model for interacting with a table:

const Sequelize = require('sequelize');
const sequelize = new Sequelize('database', 'username', 'password', {
  host: 'localhost',
  dialect: 'mysql'

const User = sequelize.define('user', {
  username: {
    type: Sequelize.STRING,
    unique: true
  password: Sequelize.STRING

2. Data Validation: Sequelize provides built-in validation and data type enforcement, helping to ensure that the data in your application’s database is consistent and conforms to the desired structure. This can reduce the risk of bugs and improve the stability of your application.

3. Data Management: Sequelize can be used to manage the creation, deletion, and modification of records in a database. The library provides a simple, intuitive API for performing these operations, making it easy to integrate database management into your application’s workflow. Additionally, Sequelize supports migrations, allowing you to evolve the structure of your database over time as your application evolves.


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