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Resolving the column "userId" does not exist Error in Sequelize Many-to-Many Relationships

A guide on troubleshooting the `column "userId" does not exist` error when setting up many-to-many relationships in Sequelize with PostgreSQL. Learn how to fix your user and template models to ensure smooth database operations. --- This video is based on the question https://stackoverflow.com/q/71226635/ asked by the user 'Fabio' ( https://stackoverflow.com/u/12130019/ ) and on the answer https://stackoverflow.com/a/71226818/ provided by the user 'Anatoly' ( https://stackoverflow.com/u/1376618/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: error: column "userId" does not exist Sequelize many-to-many relationsip Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l... The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- Understanding the column "userId" does not exist Error in Sequelize When working with Sequelize, especially while setting up many-to-many relationships, errors can arise that might seem perplexing at first glance. One such common error is: [[See Video to Reveal this Text or Code Snippet]] This issue typically arises when you misconfigure your models or the junction table that links them. In this guide, we'll explore this error further and provide a solution to fix it, ensuring your connections between users and templates behave as expected. The Many-to-Many Relationship in Sequelize Before diving into the solution, it’s essential to understand how many-to-many relationships work conceptually: User Model: Represents the users. Template Model: Represents the templates. Junction Table (User_Templates): Links the User and Template Models, allowing for the association of multiple users with multiple templates. User Model Here's how the User model looks: [[See Video to Reveal this Text or Code Snippet]] Template Model The Template model structure is as follows: [[See Video to Reveal this Text or Code Snippet]] User_Template Model (Junction Table) Here’s where things can go wrong. This is how your junction table should look: [[See Video to Reveal this Text or Code Snippet]] The Problem In your case, the mistake was in how you defined the junction table. Instead of using User_Template, you defined it with the same name as the user model: [[See Video to Reveal this Text or Code Snippet]] This redefinition caused Sequelize to look for a userId column in the users table rather than the junction table, leading to the error you encountered. The Solution To resolve this issue, follow these steps: Change the Name of the Junction Table: Make sure the junction table has a unique name that doesn’t clash with the user or template models. Change "user" to "User_Templates" in the define method of the junction model. Updated Code: [[See Video to Reveal this Text or Code Snippet]] Re-migrate Your Database: After making changes to your model definitions, ensure you run your migrations again. This will help Sequelize update the database structure to align with your model definitions. Test the Associations: Finally, test the relationships by creating instances of users and templates and saving them to the database. This way, you can verify that there are no further issues. Conclusion Encountering the column "userId" does not exist error while working with Sequelize may be frustrating, but understanding the root cause can clear the confusion quickly. By ensuring your junction table is correctly named and defined, you can establish smooth many-to-many relationships between your User and Template models. If you follow the suggestions provided in this post, you should be well on your way to resolving this error and successfully implementing the necessary relationships in your Sequelize models. Happy coding!