It also has the 'objectify' API, where you can access XML nodes via regular object access (i.e. `access.nodes[0].like.this`). http://lxml.de/objectify.html
1) you have to build libxml to use lxml
2) lxml has a large, powerful, complicated API
For 1), A friend of mine had to do an annoying workaround to use lxml on his box, due to its limited memory preventing him from being able to build libxml. Because xmltodict is Expat[1]-based, you don't have to build libxml in your environment to use it.
For 2), When I went to write a simple rss-reader project this past weekend, I dreaded going back to lxml. I knew that I'd have to go peruse its huge documentation to answer questions about whether to use lxml.XML or lxml.fromstring, whether methods I wanted were on Elements or ElementTrees, xpath syntax, custom parsers, etc. If I'd ever seen the objectify API I'd forgotten about it, because there's just so much _other_ stuff in lxml.
I happen to have found xmltodict in a brief search for lxml alternatives. It's in PyPI, so pip grabbed it with no complaints. It installed without building anything. And in less than a minute of glancing at the README, I grokked the API as "pydict = xmltodict.parse(xml_string)". I don't know if there are other things. I never had to find out.
Less than 10 minutes from finding it to forgetting I was reading XML as a source -- really a wonderful project. But if I were doing something 'serious', I'd absolutely use lxml. That large API and those byzantine docs exist for a good reason: they're dealing with XML properly. But sometimes coders just wanna have fun, or build a quick prototype or hack.
E.g. for extracting URLs from a sitemap:
from lxml import etree
root = etree.XML(data)
urls = root.xpath(
'.//sitemap:loc/text()',
namespaces={
'sitemap': 'http://www.sitemaps.org/schemas/sitemap/0.9',
}
)
import urllib2
from lxml import etree
data = urllib2.urlopen('https://news.ycombinator.com/rss').read()
root = etree.XML(data)
for i, item in enumerate(root.xpath('.//item')):
print i, item.xpath('title/text()')[0]
print item.xpath('description/text()')[0]
print item.xpath('link/text()')[0]
print
But usually, yes, LXML is "good" meaning it's the least worse way of dealing with XML
Also, it has some idiosyncrasies, like insisting on adding the namespace on tag names, so you end with something like {http://example.com/your.xlsd}.index (I don't remember it exactly and I don't have an example here with me)
I haven't used LXML in a while, but ElementTree, for example, forces you to use the QName in XPath expressions, which is technically correct but a huge pain; it would be nice if there was a ScrewNamespace option that would allow "simple" searches, although this might blow up in your face one day (when two namespaces define the same element name, and your xpath search brings up elements you didn't really want).
It's not as much as dodging the requirements but rather an inconsistency in the API.
However, while LXML can do this, and makes it easy, the documentation does not stress this way of using LXML. I like this project's emphasis on simplicity and doing one thing. It's the difference between "You can use LXML to get a dict" vs "Here is how to use xmltodict to get a dict". And it's right there in the name. Emphasis and naming are important when getting started.