Lesson 2: XML Parsing

Scenario

Suppose you want to write a code that parse any arbitery RSS feeds. Generally, the developers should have no problem with DOM iteration or XPath. However, it may become frustration for someone who just comes straight from web front-end development.

Solution

You can use yotsuba.lib.kotoba.Kotoba to help you with that. Suppose you have a variable called rss_data containing an XML data.

First, parse the data.:

from yotsuba.lib.kotoba import Kotoba
rss_xml = Kotoba(rss_data)

Then, find element item.:

raw_items = rss_xml.get("item")

Note

Now, raw_items is an instance of yotsuba.lib.kotoba.DOMElements as a result of calling the method get of yotsuba.lib.kotoba.Kotoba

Then, find elements title, link, description, comments and pubDate under each block of element item.:

for item in raw_items:
    title = item.get('title').data()
    link = item.get('link').data()
    description = item.get('description').data()
    comments = item.get('comments').data()
    publishedDate = item.get('pubDate').data()

Note

If the specified elements are not found, the method data will return an empty string.

If you want the title of the first item, you can do:

first_title = rss_xml.get("item title")
if first_title: first_title = first_title[0]

Limitation

While other libraries can parse arbitery document, even HTML 4, yotsuba.lib.kotoba.Kotoba is limited by xml.dom.minidom. So, it cannot read anything other than XML.

Additionally, yotsuba.lib.kotoba.Kotoba understands only two pseudo classes, :root and :empty.

Next, Lesson 3: Web Development

See also

Module yotsuba.lib.kotoba

XML Parser with CSS selectors

Module yotsuba.lib.aria

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