Python httpx.stream_file() Guide: Stream Files

Python's httpx library is a powerful tool for making HTTP requests. One of its standout features is the ability to stream files efficiently. This is particularly useful when dealing with large files that you don't want to load entirely into memory.

In this guide, we'll explore how to use the httpx.stream_file() method to stream files over HTTP. We'll also look at some practical examples to help you get started.

What is httpx.stream_file()?

The httpx.stream_file() method allows you to stream a file from a server to your local machine. This is done in chunks, which means you don't need to load the entire file into memory at once. This is especially useful for large files.

Streaming files can save both time and memory, making your applications more efficient. The httpx library makes this process straightforward and easy to implement.

How to Use httpx.stream_file()

To use httpx.stream_file(), you first need to install the httpx library. You can do this using pip:

pip install httpx

Once installed, you can start streaming files. Here's a basic example:

import httpx

url = "https://example.com/largefile.zip"
with httpx.stream("GET", url) as response:
    with open("largefile.zip", "wb") as file:
        for chunk in response.iter_bytes():
            file.write(chunk)

In this example, we're streaming a large file from a URL and saving it locally. The response.iter_bytes() method is used to read the file in chunks, which are then written to a local file.

Practical Example: Streaming a Large File

Let's say you need to download a large video file. Using httpx.stream_file(), you can do this efficiently:

import httpx

url = "https://example.com/largevideo.mp4"
with httpx.stream("GET", url) as response:
    with open("largevideo.mp4", "wb") as file:
        for chunk in response.iter_bytes():
            file.write(chunk)

This code will download the video file in chunks, ensuring that your application doesn't run out of memory. The file is saved locally as largevideo.mp4.

Handling Errors and Timeouts

When streaming files, it's important to handle errors and timeouts. The httpx library provides several options for this. For example, you can set a timeout for the request:

import httpx

url = "https://example.com/largefile.zip"
try:
    with httpx.stream("GET", url, timeout=30.0) as response:
        with open("largefile.zip", "wb") as file:
            for chunk in response.iter_bytes():
                file.write(chunk)
except httpx.TimeoutException:
    print("The request timed out.")
except httpx.RequestError as e:
    print(f"An error occurred: {e}")

In this example, we've set a timeout of 30 seconds. If the request takes longer than this, a TimeoutException will be raised. We also handle other request errors using a RequestError.

Conclusion

Streaming files with httpx.stream_file() is a powerful way to handle large files efficiently. By reading files in chunks, you can save memory and improve the performance of your applications.

Whether you're downloading large videos, datasets, or other files, httpx makes it easy to stream content without overwhelming your system. For more advanced use cases, consider exploring other streaming methods like httpx.stream_raw() or httpx.stream_lines().

With the examples and tips provided in this guide, you should be well-equipped to start streaming files in your Python projects. Happy coding!