When working with XML files in Python, it's important to ensure that namespaces remain within their respective elements without moving to the root element. The `lxml` library provides more flexible handling of XML namespaces, making it a better choice for such tasks.
Step 1: Install the lxml Library
First, install the `lxml` library if you haven't already:
Step 2: Update XML with lxml
Here is the updated code using `lxml` to handle XML content and maintain namespace integrity:
from lxml import etree
Sample XML content as a string
xml_content = '''<root>
<AppHdr xmlns="urn:swift:xsd:$ahV10">
<MsgRef>TRNREF001</MsgRef>
<CrDate>2009-05-08T22:02:36.218+02:00</CrDate>
</AppHdr>
<ns:Document xmlns:ns="urn:swift:xsd:setr.010.001.03">
<ns:SbcptOrdrV03>
<ns:MsgId>
<ns:Id>TRNREF001</ns:Id>
<ns:CreDtTm>2007-04-25T10:10:30.000+02:00</ns:CreDtTm>
</ns:MsgId>
<ns:MltplOrdrDtls>
<ns:InvstmtAcctDtls>
<ns:AcctId>
<ns:Prtry>
<ns:Id>1111
</ns:Id>
</ns:Prtry>
</ns:AcctId>
<ns:AcctDsgnt>SMART INVESTOR</ns:AcctDsgnt>
</ns:InvstmtAcctDtls>
<ns:IndvOrdrDtls>
<ns:OrdrRef>TRNREF001</ns:OrdrRef>
<ns:FinInstrmDtls>
<ns:Id>
<ns:ISIN>GB1234567890</ns:ISIN>
</ns:Id>
</ns:FinInstrmDtls>
<ns:GrssAmt Ccy="GBP">1050</ns:GrssAmt>
<ns:IncmPref>CASH</ns:IncmPref>
<ns:PhysDlvryInd>false</ns:PhysDlvryInd>
<ns:ReqdSttlmCcy>GBP</ns:ReqdSttlmCcy>
<ns:ReqdNAVCcy>GBP</ns:ReqdNAVCcy>
</ns:IndvOrdrDtls>
</ns:MltplOrdrDtls>
</ns:SbcptOrdrV03>
</ns:Document>
</root>'''
Parse the XML content
root = etree.fromstring(xml_content)
Namespaces dictionary
namespaces = {
'ah': 'urn:swift:xsd:$ahV10',
'ns': 'urn:swift:xsd:setr.010.001.03'
}
Update the value of <MsgRef> in <AppHdr>
msg_ref = root.find('.//ah:MsgRef', namespaces)
if msg_ref is not None:
msg_ref.text = 'NEWTRNREF001'
Update the value of <ns:Id> in <ns:MsgId>
msg_id = root.find('.//ns:MsgId/ns:Id', namespaces)
if msg_id is not None:
msg_id.text = 'NEWTRNREF001'
Convert the updated XML tree back to a string
updated_xml_content = etree.tostring(root, pretty_print=True, xml_declaration=True, encoding='UTF-8').decode('utf-8')
print(updated_xml_content) |
Explanation
1. Parse the XML Content: The XML content is parsed using `etree.fromstring()`.
2. Namespace Dictionary: A dictionary of namespaces is defined with prefixes to simplify XPath expressions.
3. Update Elements:
The `MsgRef` element within the `AppHdr` element is found and updated.
The `Id` element within the `MsgId` element (which is nested within the `Document` element) is found and updated.
4. Output Updated XML: The updated XML content is converted back to a string with pretty printing and the XML declaration.
Benefits of Using lxml
Namespace Handling: `lxml` maintains namespaces within their respective elements without moving them to the root, ensuring XML integrity.
XPath Support: `lxml` provides robust support for XPath, making it easier to find and update elements in an XML document.
Pretty Printing: The output XML can be formatted for better readability.
By using `lxml`, you can effectively manage XML namespaces and ensure that your XML structure remains intact during updates.
