1.
csp-10-2-1: What is the last thing (last line of text) that will be printed when the code below runs?
Exercises 15.2 Parsing XML
Look at the code below and predict what will be printed.
Here is a simple application that parses some XML and extracts some data elements from the XML:
2.
Run this to see what it prints.
import xml.etree.ElementTree as ET
data = '''
<person>
<name>Chuck</name>
<phone type="intl">
+1 734 303 4456
</phone>
<email hide="yes"/>
</person>'''
tree = ET.fromstring(data)
print('Name:', tree.find('name').text)
print('Attr:', tree.find('email').get('hide'))
The triple single quote (
'''), as well as the triple double quote ("""), allow for the creation of strings in Python that span multiple lines.Calling
fromstring converts the string representation of the XML into a “tree” of XML elements. When the XML is in a tree, we have a series of methods we can call to extract portions of data from the XML string. The find function searches through the XML tree and retrieves the element that matches the specified tag. The get gets the value of the attribute in that tag.Using an XML parser such as
ElementTree has the advantage that while the XML in this example is quite simple, it turns out there are many rules regarding valid XML, and using ElementTree allows us to extract data from XML without worrying about the rules of XML syntax.Using get to get the value of an attribute
3.
csp-10-2-3: What is the last thing (last line of text) that will be printed when the code below runs?
4.
Run this to see what it prints.
import xml.etree.ElementTree as ET
data = '''
<person>
<name>Chuck</name>
<phone type="intl">
+1 734 303 4456
</phone>
<email>csev@umich.edu</email>
</person>'''
tree = ET.fromstring(data)
print('Name:', tree.find('name').text)
print('Attr:', tree.find('email').get('hide'))
Getting Data from the First Element of a Type in XML
You can use
find to get the first element of the XML of a specified type. You can the use find on that element to get children tags of that element.5.
Run the code to see what this prints.
import xml.etree.ElementTree as ET
data = '''
<bookstore>
<book category="cooking">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year calendar="Gregorian">2005</year>
<price>30.00</price>
</book>
<book category="CHILDREN">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
</bookstore>
'''
tree = ET.fromstring(data)
book = tree.find('book')
print('Author:', book.find('author').text)
print('Lang:',book.find('title').get('lang'))
What do you think would happen if we looked for the first ‘author' in
tree rather than in book? Modify the code to see what happens.Fixing Errors in XML
If your XML has errors, what do you think will happen?
6.
The following XML has errors. Try to run the code first to see what happens and then fix the XML so that the code runs correctly.
import xml.etree.ElementTree as ET
data = '''
<bookstore>
<book category="mystery">
<title lang="en">The Personal Librarian
<author>Giada Marie Benedict<author>
<year calendar=Gregorian>2021</year>
<price>19.85</price>
<book\>
</bookstore>
'''
tree = ET.fromstring(data)
book = tree.find('book')
print('Author:', book.find('author').text)
print('Title:', book.find('title').text)
print('Lang:',book.find('title').get('lang'))
7.
The following XML has errors. Try to run the code first to see what happens and then fix the XML so that the code runs correctly.
import xml.etree.ElementTree as ET
data = '''
<messages>
<note id="p501">
<time region="EST">11:00am</time>
Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
</body>Don't forget me this weekend!</body>
</note>
<note id="p502">
<time region=EST>1:00pm</time>
<to>Jani</to>
<from>Tove
<heading>Re: Reminder</heading>
<body>I will not!<body>
</note>
</messages>
'''
tree = ET.fromstring(data)
note = tree.find('note')
print('to:', note.find('to').text)
print('body:', note.find('body').text)
print('time region:',note.find('time').get('region'))
Write Code to Process XML
8.
Write code to print the book title, category, author, and year.
import xml.etree.ElementTree as ET
data = '''
<bookstore>
<book category="Cultural Heritage Fiction">
<title lang="en">The Turner House</title>
<author>Angela Flournoy</author>
<year>2016</year>
</book>
</bookstore>
'''
9.
Write code to print the note's to, from, body, and time (with region).
import xml.etree.ElementTree as ET
data = '''
<messages>
<note id="p501">
<time region="EST">11:00am</time>
<to>Zihan</to>
<from>Xinyin</from>
<heading>Reminder</heading>
</body>Don't forget the talk!</body>
</note>
'''
