How to Fix Asynchronous Data Return Issues in Node.js Using async/await

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The Problem: Not Waiting for Data from the Backend

Imagine you have a function designed to authenticate a user by querying a MongoDB collection. Here's a simplified version of what your backend function looks like:

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

The Issue at Hand

When you call this function from the frontend using await, the backend may not complete its tasks before returning a value. Consequently, your application might print unexpected results or encounter an undefined state.

To illustrate, in the front-end you may use:

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

The Solution: Wrapping Your Code in a Promise

To ensure that the backend function resolves correctly before continuing with the frontend code, you can wrap your function's logic within a Promise. This allows you to resolve the function’s results based on the completion of the database query.

Here’s How You Do It:

Create a New Promise: You will wrap your function’s body in a new Promise and resolve or reject this promise based on the result of your database query.

Modify Your Function: See the modified code below for the new structure of your backend function:

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

Key Changes Made:

Promise Creation: The function now returns a Promise, encapsulating all logic.

Error Handling: If an error occurs during the database connection, the Promise rejects, allowing the frontend to handle the error gracefully.

Resolving Values: The function resolves true or false based on the presence of the query results, allowing for accurate feedback to the caller.

Conclusion

By encapsulating your asynchronous logic within a Promise, you can easily manage the flow of your asynchronous code and ensure that your frontend waits for the backend to provide a response. This way, your application remains reliable, predictable, and easy to debug.

Using async/await in combination with Promises allows you to write cleaner, more maintainable code, preventing common pitfalls associated with asynchronous programming.