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Learn why you see the 'coroutine was never awaited' error in Python and how to properly await a coroutine to resolve the issue effectively.
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Resolving the coroutine was never awaited Error in Python's asyncio

If you’re working with Python’s asyncio, you may have encountered an error that states something along the lines of coroutine was never awaited. This message can be frustrating, especially when you believe you’ve correctly implemented the await keyword in your function. In this post, we’ll explore what this error means, why you might be seeing it, and how to resolve it effectively.

Understanding coroutine was never awaited

The error coroutine was never awaited typically occurs when you call an asynchronous function but forget to use the await keyword. In Python, when you define a function using the async keyword, it returns a coroutine object. This object needs to be awaited in order to execute properly.

The Problem

The issue arises in scenarios where you're returning a coroutine from another function, but you fail to await it. Here’s a breakdown of the scenario leading to the error:

Example Code

Consider the following function that aims to run asynchronously:

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

In the above code, _aio is designed to wrap a function f with asynchronous behavior. When using this function, you might call it like this:

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

At this point, you might think that res contains the result you want. However, this is not the case.

Why It Fails

Due to how the _aio function is constructed, calling self._aio(self._client.get_object) returns an async function (coroutine), but does not execute it. This is why Python complains that the coroutine was never awaited.

How to Fix the Error

To resolve this issue, you need to ensure you await the coroutine returned from the aio_wrapper. This can be accomplished with a simple adjustment to your code:

Corrected Code

Replace the line where you're calling _aio like this:

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

Key Points

Always Use await: Whenever you call an asynchronous function (a coroutine), make sure to use await to ensure execution.

Understanding Coroutines: When you create an asynchronous function using async def, remember it returns a coroutine that needs to be awaited.

Conclusion

In summary, the error message coroutine was never awaited points to a common pitfall in asynchronous programming with Python's asyncio. Always ensure you are using await when working with coroutines to execute them correctly. With this simple change, you can eliminate the error and leverage the full power of asynchronous programming in Python.

Now, go ahead and adjust your code accordingly, and happy coding with asyncio!