Parse, Edit, and Write KML

This guide covers the most common production workflow with fastkml: load an existing document, inspect or update a few features, and write the result back out. The important part is that you work with the object graph, not raw XML strings. That gives you normal Python mutation semantics while keeping the final serialization namespace-aware and schema-compatible.

  1. Parse the input document

>>> from pathlib import Path
>>> from fastkml import KML

>>> source = Path("docs/Document-clean.kml")
>>> k = KML.parse(source, strict=True, validate=False)

>>> print([type(f).__name__ for f in k.features])
['NetworkLinkControl', 'Document']

  1. Find the feature you want to change

>>> from fastkml import Placemark, StyleUrl
>>> from fastkml.utils import find

>>> placemark = find(k, of_type=Placemark, name="Vancouver Film Studios")
>>> placemark.name = "Updated Feature"
>>> placemark.style_url = StyleUrl(url="#updated-style")

  1. Write KML or KMZ output

>>> import tempfile
>>> from pathlib import Path

>>> with tempfile.TemporaryDirectory() as tmp_dir:
...     kml_path = Path(tmp_dir) / "output.kml"
...     kmz_path = Path(tmp_dir) / "output.kmz"
...     k.write(kml_path, prettyprint=True, precision=6)
...     k.write(kmz_path, prettyprint=True, precision=6)
...     print(kml_path.exists())
...     print(kmz_path.exists())
...
True
True

This flow is backed by KML.parse() and KML.write() in fastkml/kml.py. parse() handles namespace inference, optional schema validation, and object construction through _XMLObject.class_from_element(). write() serializes the same object graph and switches to ZIP output automatically when the target path ends in .kmz.

Two details are worth remembering in real jobs. First, if the source document uses nonstandard extension elements, pass validate=False or register those extensions before parsing (see the “Extending FastKML” section of Working with KML Files). Second, write() does not do directory creation for you, so use a real output path. Everything else is ordinary Python object mutation.