Extract and Parse ODF Files with Python

import sys, zipfile
myfile = zipfile.ZipFile(sys.argv[1])
listoffiles = myfile.infolist()
for s in listoffiles:    print s.orig_filename

The import statement allows you to use the sys module for getting a command-line argument of the file, and the zipfile module loads in the functionality for reading and unzipping files. As you saw from the Python shell, the infolist() method on the zipfile archive lists the files in it. So iterating over the items from the infolist() and then calling an orig_filename member function gives you a list of all files in the archive.

For more detailed information, try something like this:

print s.orig_filename, s.date_time, s.filename,
 ↪s.file_size, s.compress_size

You will receive more information about the file, quite similar to this:

mimetype (2006, 9, 9, 7, 50, 10) mimetype 39 39
Configurations2/statusbar/ (2006, 9, 9, 7, 50, 10)
Configurations2/statusbar/ 0 0
Configurations2/accelerator/current.xml
 ↪(2006, 9, 9, 7, 50, 10)
Configurations2/accelerator/current.xml 0 2
Configurations2/floater/ (2006, 9, 9, 7, 50, 10)
Configurations2/floater/ 0 0
...SNIPPED FOR BREVITY...

A typical ODF text file (with the .odt extension) will have some of the following files when unzipped. Here's the output:

mimetype
Configurations2/statusbar/
Configurations2/accelerator/current.xml
Configurations2/floater/
Configurations2/popupmenu/
Configurations2/progressbar/
Configurations2/menubar/
Configurations2/toolbar/
Configurations2/images/Bitmaps/
layout-cache
content.xml
styles.xml
meta.xml
Thumbnails/thumbnail.png
settings.xml
META-INF/manifest.xml

The most important file in the archive is the content.xml file, because it contains the data for the document itself. I discuss this file here; however, for detailed information on each tag and so on, take a look at the specification in the 2,000+-page PDF file from the OASIS Web site (see Resources).

Basically, the content.xml file looks like a DHTML file with tags for all the contents. The tag I was concerned with most for my search operation was the <text:p> tag and its closing tag </text:p>, which wraps paragraphs in a document. I'll show you how to get this tag from a content file later in this article.

Other files of interest in the archive are the META-INF/manifest.xml, mimetype, meta.xml and styles.xml. Other files simply contain data for configurations for the word processors reading and displaying the contents file.

The manifest is simply an XML file with a listing of all the files in the zipped archive. The mimetype file is a single line containing the mimetype of the content file. The meta.xml contains information about the author, creation date and so on. The styles file contains all the formatting styles for displaying the file.

You can extract any of these files from the ODF file with the read() method on the zip object to get it as a very long string. Once read, you can modify, view and write the whole string to disk as an independent file. Listing 3 shows how to extract the manifest.xml file.

import sys, zipfile
if len(sys.argv) < 2:
    print "Usage: extract odf-filename outputfilename
    sys.exit(0)

myfile = zipfile.ZipFile(sys.argv[1])
listoffiles = myfile.infolist()
for s in listoffiles:
    if s.orig_filename == 'META-INF/manifest.xml':
            fd = open(sys.argv[2],'w')
            bh = myfile.read(s.orig_filename)
            fd.write(bh)
            fd.close()

For more than one file, you can use a list instead of the if clause:

if s.orig_filename in ['content.xml', 'styles.xml']:

This way, you can extract whatever files you need to look at simply by reading in their contents and either manipulating them or writing them off to disk.

The contents of an XML file are best suited for manipulation as a tree structure. Use the XML parsing capabilities in Python to get a tree of all the nodes within an XML file. Once you have the tree in a content file, you easily can get to the <text:p> nodes. You don't really have to extract the file to disk, because you also can run an XML parser on the string just as well as reading from a file.

There are two types of XML parsers, SAX and DOM. The SAX parser is faster but less memory-intensive, because it reads and parses an input file one tag at a time. You have only one tag at a time to work with and must track data yourself. In contrast, the DOM parser reads the entire file into memory and therefore provides better options for navigating and manipulating the XML nodes.

Let's look at examples of using both SAX and DOM, so you can see which one suits your purpose. The SAX example shows how to extract unique node names from an XML file. The DOM example illustrates how to read values from within specific nodes once the file has been read completely into memory.

First, let's use the SAX parser to see what nodes are available in the content.xml file. The code simply prints the name of each type node found in the file. Note that for different types of files you may get different node names (Listing 4).