Streaming Large Files

In this lesson, we're going to learn how to handle large files with Python requests library. Streaming large files can be a challenging task, but Python's requests library makes it a breeze. Let's start with understanding what streaming is, then we'll move on to practical examples.

What is Streaming?

In the context of file handling, streaming refers to the process of continuously reading or writing data. Instead of loading the whole file into memory at once, we handle it piece by piece. This is especially useful when dealing with large files that may exceed your system's memory if handled improperly.

Streaming Large Files with Python Requests

Python's requests library provides an excellent way to handle large files: stream parameter. When you set stream=True in your request, the data will not be loaded into memory all at once, but streamed instead.

Here's a simple example of downloading a large file:

import requests

url = 'http://example.com/large-file.pdf'
response = requests.get(url, stream=True)

with open('large-file.pdf', 'wb') as fd:
    for chunk in response.iter_content(chunk_size=1024):
        fd.write(chunk)

In the above code:

• We set stream=True in the get method.
• response.iter_content(chunk_size=1024) is used to iterate over the content chunk by chunk. The chunk size is the amount of data that should be read on each iteration - in this case, 1024 bytes.
• We open a file in write-binary mode ('wb') and write each chunk to it.

Error Handling and Cleanup

It's important to handle potential errors and close the response after we're done with it. We can use a try/except/finally block for this. Let's modify the previous example

import requests

url = 'http://example.com/large-file.pdf'
response = requests.get(url, stream=True)

try:
    with open('large-file.pdf', 'wb') as fd:
        for chunk in response.iter_content(chunk_size=1024):
            fd.write(chunk)
except Exception as e:
    print(f"Error occurred: {e}")
finally:
    response.close()

In the modified code, we added:

• A try/except/finally block. If an error occurs during the download or writing to the file, we print the error message and then close the response in the finally block.

Conclusion

Streaming large files with Python's requests library is a straightforward process. We can download large files without worrying about memory limitations by using stream=True and iter_content. Also, remember to always handle potential errors and clean up afterwards by closing the response.

In the next lesson, we'll dive deeper into the requests library and explore other advanced topics. Stay tuned!