How to Fix Node Postgres Query Returning Undefined Instead of Results

Discover how to resolve issues with your Node Postgres queries returning undefined results, and learn best practices for using async/await in your database interactions.
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How to Fix Node Postgres Query Returning Undefined Instead of Results

The Problem

Consider the following function designed to fetch classes from a PostgreSQL database:

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Understanding Why It Returns Undefined

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The Solution

To resolve this issue, we can simplify our function and avoid using callback patterns altogether. Instead, we will utilize the Promise-based API. Here’s how to change your getClasses function:

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Key Changes Made

Async/Await: The function is now fully asynchronous, leveraging await to pause execution until the connection is established and the query is completed.

Elimination of the Callback: By removing the callback style, we ensure that the getClasses function can return the query results directly as a promise that resolves to the fetched classes.

Proper Resource Management: The use of try/finally ensures that the database client always gets released back to the pool, even if an error occurs during the query execution.

Conclusion

By implementing these changes, you should now be able to fetch your classes without encountering undefined return values. Happy coding!