Adding a new descriptive metadata template element to all assets in a folder

add-element.py

from xml.etree import ElementTree
from pyPreservica import *
client = EntityAPI()
folder = client.folder("723f6f27-c894-4ce0-8e58-4c15a526330e")
for child_asset in filter(only_assets, client.descendants(folder.reference)):
    asset = client.asset(child_asset.reference)
    xml_document = ElementTree.fromstring(client.metadata_for_entity(asset, "your-xml-namespace"))
    new_Element = ElementTree.Element('{your-xml-namespace}your-element-name')
    new_Element.text = "Value"
    xml_document.append(new_Element)
    xml_string = ElementTree.tostring(xml_document, encoding='UTF-8', xml_declaration=True).decode("utf-8")
    asset = entity.update_metadata(asset, "your-xml-namespace", xml_string) 
    print("Updated asset: " + asset.title)