Python File Uploads: Understanding if, try, and except Exception

These Python statements are commonly used when handling uploaded files, especially in applications built with Streamlit.

1. Check whether a file was uploaded

if uploaded_file is not None:

• if checks a condition.
• uploaded_file is a variable that holds the uploaded file.
• is not None checks that the variable contains a value rather than None.

Purpose: Run code only when a file has been uploaded.

2. Use try to run code safely

try:

• try contains code that Python attempts to execute.
• If the code succeeds, Python continues normally.
• If an exception occurs, Python can move to an except block.

Purpose: Handle operations that might fail, such as reading or processing a file.

3. Use except Exception to handle errors

except Exception:

• except = handles an error.
• Exception = specifies which category of errors to catch.

Purpose: Handle errors that occur during execution.

4. Combine all three

if uploaded_file is not None:
    try:
        # your code goes here
    except Exception:
        # Error handling goes here

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This mini-guide was originally published on PDF Python Hub, where you can find more in-depth Python resources for working with PDFs.