数据流 - XML 源 - Python - 如何？

Question

I'm trying to source an XML file into my dataflow code. I see java has a built in XMLIo but Python doesn't? I'm also struggling to understand what are the initial steps to ParDo/DoFn it myself. This is an example of the XML file below. My pipeline below when parsing .csv I understand but I'm not understanding how to start with an XML source. Do I need to manually create a PCollection and go from there?

My goal is to return each element as a tuple. The key would be the country name and each element after (in a nested array) would be the values.

<?xml version="1.0"?>
<data>
    <country name="Liechtenstein">
        <rank>1</rank>
        <year>2008</year>
        <gdppc>141100</gdppc>
        <neighbor name="Austria" direction="E"/>
        <neighbor name="Switzerland" direction="W"/>
    </country>
    <country name="Singapore">
        <rank>4</rank>
        <year>2011</year>
        <gdppc>59900</gdppc>
        <neighbor name="Malaysia" direction="N"/>
    </country>
    <country name="Panama">
        <rank>68</rank>
        <year>2011</year>
        <gdppc>13600</gdppc>
        <neighbor name="Costa Rica" direction="W"/>
        <neighbor name="Colombia" direction="E"/>
    </country>
</data>

def run():
   argv = [
      '--project={0}'.format(PROJECT),
      '--staging_location=gs://{0}/'.format(BUCKET),
      '--temp_location=gs://{0}/'.format(BUCKET),
      '--runner=DataflowRunner'
      #'--runner=DirectRunner'
   ]

   p = beam.Pipeline(argv=argv)

   (p
      | 'ReadFromGCS' >> beam.io.textio.ReadFromText('gs://{0}/example.csv'.format(BUCKET))
-[SNIP]-

Answer 1

The code below will collect each country information.

The output is a list of tuples.

The first element in the tuple is the country name and the second element is a list of the other country properties.

import xml.etree.ElementTree as ET


xml = '''<?xml version="1.0"?>
<data>
    <country name="Liechtenstein">
        <rank>1</rank>
        <year>2008</year>
        <gdppc>141100</gdppc>
        <neighbor name="Austria" direction="E"/>
        <neighbor name="Switzerland" direction="W"/>
    </country>
    <country name="Singapore">
        <rank>4</rank>
        <year>2011</year>
        <gdppc>59900</gdppc>
        <neighbor name="Malaysia" direction="N"/>
    </country>
    <country name="Panama">
        <rank>68</rank>
        <year>2011</year>
        <gdppc>13600</gdppc>
        <neighbor name="Costa Rica" direction="W"/>
        <neighbor name="Colombia" direction="E"/>
    </country>
</data>'''

result = []
root = ET.fromstring(xml)
for country in root.findall('.//country'):
    result.append((country.attrib['name'],[x.text if x.text else x.attrib for x in list(country)]))
print(result)

output

[('Liechtenstein', ['1', '2008', '141100', {'name': 'Austria', 'direction': 'E'}, {'name': 'Switzerland','direction': 'W'}]), ('Singapore', ['4', '2011', '59900', {'name': 'Malaysia', 'direction': 'N'}]), ('Panama', ['68', '2011', '13600', {'name': 'Costa Rica', 'direction': 'W'}, {'name': 'Colombia', 'direction': 'E'}])]