Document use of MARCXML with an example

[nichtich]

We are still trying to find out how to parse and serialize MARCXML. I then stumbled upon #73 (make it simpler) but one or two examples in the documentation may be enough to start with:

• how to read a full MARCXML file
• how to read a stream of records from a MARCXML file (maybe this helps)
• how to serialize MARC records to XML

P.S: See also this help request.

[edsu]

Sure, I'd be happy to merge those docs. Although the referenced ticket, which I've intentionally left open, makes it sound like there could be a preferable API for reading/writing XML?

[edsu]

@nichtich do you know if lxml.etree.iterparse reads the entire document into memory, and then iterates over that?

[edsu]

@nichtich Will this new documentation help clarify the current state of affairs with XML and JSON? It can always get updated if there does turn out to be progress on #73. If you have any suggestions for improving it please send them along.

[nichtich]

@edsu Thanks for the new documentation that's very helpful, I did not know about map_xml. Writing XML is possible nevertheless. The following is possibly no beautiful Python but should work:

# write XML header to file object
file.write('<?xml version="1.0" encoding="UTF-8"?>\n')
file.write('<collection xmlns="http://www.loc.gov/MARC21/slim">\n')

# write records
for record in records:
     file.write(marcxml.record_to_xml(record).decode("utf-8"))
     file.write('\n')

# write XML footer
file.write('</collection>')
file.close()

[edsu]

That would be better expressed in a separate pull request. If the documentation suffices for now I'm going to close this.