How to extract element from two similar tags in one code?-CodePudding

I am trying to extract year from multiple xml files. Initially, the xml files are as follows,

<Return xmlns="http://www.irs.gov/efile" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.irs.gov/efile" returnVersion="2018v3.2">
  <ReturnHeader binaryAttachmentCnt="0">
    <!-- ... -->
    <TaxPeriodEndDt>2019-09-30</TaxPeriodEndDt>
    <!-- ... -->
  </ReturnHeader>
  <ReturnData documentCnt="12">
    <!-- ... -->
  </ReturnData>
</Return>

I used

year = root.find('.//irs:TaxPeriodEndDt',ns).text[:4]

It had worked well. But in some xml files the tag is changed to TaxPeriodEndDate

<Return xmlns="http://www.irs.gov/efile" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.irs.gov/efile" returnVersion="2018v3.2">
  <ReturnHeader binaryAttachmentCnt="0">
    <!-- ... -->
    <TaxPeriodEndDate>2012-09-30</TaxPeriodEndDate>
    <!-- ... -->
  </ReturnHeader>
  <ReturnData documentCnt="12">
    <!-- ... -->
  </ReturnData>
</Return>

I tried to revise the code to

year = root.find('.//irs:TaxPeriodEndDt|.//irs:TaxPeriodEndDate',ns).text[:4]

It did not work. No error message, but no output. Any suggestion is highly appreciated. Thank you.

CodePudding user response：

The support for xpath in ElementTree is very limited. The union operator (|) doesn't appear to work and other options, like using the self:: axis or name()/local-name() in a predicate, aren't supported.

I think your best bet is to use a try/except...

try:
    year = root.find(".//irs:TaxPeriodEndDt", ns).text[:4]
except AttributeError:
    year = root.find(".//irs:TaxPeriodEndDate", ns).text[:4]

If you can switch to lxml, your original attempt with the union operator will work with a few small changes (mainly use xpath() instead of find() and use the namespaces keyword arg)...

year = root.xpath(".//irs:TaxPeriodEndDt|.//irs:TaxPeriodEndDate", namespaces=ns)[0].text[:4]