viaf_snippet_2.py

from lxml import etree

def get_lc_auth_from_viaf_data(response):
    lc_auth = ""
    
    # parse the returned xml into an lxml etree
    tree = etree.fromstring(response)
    
    # extract a list of the VIAF search result nodes using an xpath query
    results = tree.xpath("//*[local-name()='record']")
    
    # if there are any search results, grab the first one
    if len(results) > 0:
        primary_result = results[0]
        
        # Extract all auth sources for this search result
        sources = primary_result.xpath("//*[local-name()='mainHeadingEl']/*[local-name()='id']")
        
        # There are usually a number of sources, but we only want the LoC
        for source in sources:
            if "LC|" in source.text:
                
                # needs some formatting to extract the number only
                lc_auth = source.text.split("|")[1].replace(" ", "")
                break

    return lc_auth