Reference library

Data pipelines & processing

ETL-style flows, batch transforms, validation, and moving data between formats.

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Data pipelines & processing easy

Trigger a Pipeline When a New File Appears in a Directory

Poll a directory every 0.5 seconds and return the name of the first new file that appears, or None after a timeout.

polling filesystem file-watcher
Python 
import time
from pathlib import Path


def watch_for_file(directory: str, interval: float = 0.5, timeout: float = 10.0) -> str | None:
    """Poll a directory and trigger when a new file appears."""
    watch_dir = Path(directory)
    watch_dir.mkdir(exist_ok=True)
    
    known_files = set(watch_dir.iterdir())
    s…
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