Resolving UnhandledPromiseRejectionWarning in Sequelize: Filtering by Foreign Key in Related Models

Описание: Learn how to handle the `Unknown column` error in Sequelize by correctly filtering with foreign keys in related model queries.
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This video is based on the question https://stackoverflow.com/q/65570523/ asked by the user 'yaser OtakU' ( https://stackoverflow.com/u/10056118/ ) and on the answer https://stackoverflow.com/a/65570923/ provided by the user 'Elenka29' ( https://stackoverflow.com/u/14884432/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving UnhandledPromiseRejectionWarning in Sequelize: Filtering by Foreign Key in Related Models

Working with models in Sequelize can sometimes lead to frustrating errors, especially when dealing with relationships between different models. A common issue that developers face is the UnhandledPromiseRejectionWarning: SequelizeDatabaseError: Unknown column error. This post will walk you through understanding this error and how to resolve it when searching for a userId from a related model.

The Problem

Suppose you're using Sequelize, a powerful ORM for Node.js, to manage your database interactions. You've defined a Comment model that relates to a TaskCustomerOrder model. When you try to search for comments by the userId from the TaskCustomerOrder, you encounter an error stating that the column in the where clause is unknown.

Here's the code that triggers the error:

[[See Video to Reveal this Text or Code Snippet]]

Error Message

The error you see is:

[[See Video to Reveal this Text or Code Snippet]]

Understanding the Error

The error arises because the where condition tries to access userId directly on the task_customer_order model. It attempts to treat it as if it’s a property of the Comment model, which isn't correct. Instead, to filter results based on a related model, you should leverage the include option appropriately.

The Solution

To filter by the userId in the task_customer_order model, you need to move the condition into the include section of your query. Here’s how you can modify your code:

[[See Video to Reveal this Text or Code Snippet]]

Changes Made:

Moved the Condition: The where condition for userId is now inside the include for TaskCustomerOrder. This specifies that you're filtering the TaskCustomerOrder model based on the userId.

Focus on Relationships: By appropriately targeting the relationship between the models, you ensure that Sequelize understands where to look for the data.

Key Points to Remember:

Always place conditions related to included models inside the include array.

Accessing properties of related models needs to be done with consideration for how Sequelize constructs queries.

Use clear, organized code to maintain readability and ease of debugging when working with complex queries.

Conclusion

By understanding how to effectively filter through related models in Sequelize, you can avoid common errors like the UnhandledPromiseRejectionWarning. Now, you have the knowledge to properly search for a userId in the task_customer_order model without running into the Unknown column error. If you encounter similar issues, remember to check the scope of your where clauses and verify their placement in the appropriate model context.

Happy coding!