Extract and Parse ODF Files with Python

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Use Python to demystify Open Document Format files.

The Open Document Format (ODF) Alliance is designed for sharing information between different word processing applications. This article highlights the basic structure of ODF files, some internals of the underlying XML files and shows how to use Python to read the contents to perform a simple search for keywords. The code also can be the basis for more-advanced operations. In the spirit of openness, we use open-source software to read the ODF files, which in this case are Python and the OpenOffice.org package.

If you are running a recent version of Linux or OS X, you already should have Python and OpenOffice.org installed on your machine. If you need the latest versions, Python is available for free from www.python.org for both the Windows and Linux platforms. The OpenOffice.org package also is available for free from www.openoffice.org. Installing OpenOffice.org on an XP desktop is relatively painless. Download the packages from their respective sites and run the installer. Once installed, simply run the application from the desktop with a click on the installed icons.

Once you have confirmed that you have the prerequisites, you can create an ODF file. Open up the Writer, type some text in a document and save it. You can read in a file and save it as an .odt file.

A quick look at extensions in the Save dialog reveals a lot. An ODF file can have many extensions, which provide a clue as to the type of information stored in it and the application that stored it. See Table 1.

Table 1. ODF File Types and Their Extensions

Document FormatFile Extension
OpenDocument Text *.odt
OpenDocument Text Template*.ott
OpenDocument Master Document*.odm
HTML Document*.html
HTML Document Template*.oth
OpenDocument Spreadsheet*.ods
OpenDocument Spreadsheet Template*.ots
OpenDocument Drawing*.odg
OpenDocument Drawing Template*.otg
OpenDocument Presentation*.odp
OpenDocument Presentation Template*.otp
OpenDocument Formula*.odf
OpenDocument Database*.odb

So, what's in an ODF file? An ODF file is basically a zipped archive with several XML files. The actual files and directories in a file will vary depending on the type of information and the system on which the document was created.

The first step in picking out the names of the files in an ODF file requires unzipping the file itself. Fortunately, Python has built-in support for dealing with this endeavor with the zipfile module. Type python on the command line to run an interactive shell. Running a shell allows you to examine the contents of objects returned from the modules. Because you'll probably be doing this only once per type of data, there is really no need to write and execute a script at this time. If you want to preserve the work for future use, it's better to write a script in a text editor or use the IDLE editor that comes with Python and save the script. See Listing 1 on how to show the member functions in a class or module.

The infolist() command from the Python documentation returns a list the objects of a zipped archive. Run the dir() command on the first object from this list to get more information stored for each zipped file (Listing 2). This nice feature of looking at members in an object is called introspection.

An iteration on the list of objects displays relevant information about each file, such as when it was created, its extracted size, its compressed size and so on. It's better at this point to write a Python script and run it rather than work at the command line of an interactive Python shell. This way, you can preserve the script for later use. So, open up a text editor and type in the script.

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File is not a zip file

hypertex's picture

I am trying to run listing 5. Am I the only one receiving this error?


File "./odt.py", line 13, in __init__
self.m_odf = zipfile.ZipFile(filename)
File "/usr/lib/python2.6/zipfile.py", line 693, in __init__
self._GetContents()
File "/usr/lib/python2.6/zipfile.py", line 713, in _GetContents
self._RealGetContents()
File "/usr/lib/python2.6/zipfile.py", line 725, in _RealGetContents
raise BadZipfile, "File is not a zip file"
zipfile.BadZipfile: File is not a zip file

and yet . . .

>>> odfname = ('bill_of_rights.odt')
>>> zipfile.is_zipfile(odfname)
True

I'm confused is_zipfile() returns true, but I get a BadZipfile exception. Same result with several different files, so I don't think it is a bad file. Running python 2.6.4 on fedora 13.

D'OH!

hypertex's picture

the __main__ block should have:

filename = sys.argv[1]
phrase = sys.argv[2]

I keep forgetting that sys.argv[0] is a reference to the script, not the first argument to the script.

LPOD Project

Anonymous's picture

lpod is an ODF library that allow to easily manipulate ODF documents.

Fail? What fail?

Anonymous's picture

To the first commenter, win32 doesn't mean windows 3.2. It means 32-bit windows.
(Windows NT/2000/XP/Vista/7)

FAIL!

Anonymous's picture

Python 2.4.1 (#65, Mar 30 2005, 09:13:57)
[MSC v.1310 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()"
for more information.

however, very good tutorial doh! ;)

greets
Royma

Nice

Nichoals's picture

Nice tutorials.. You'r the only one in the net that write something aboute odt and python clearly.
Do you have a tutorials to pick pictures from the odt file too?

uçak bileti

uçak bileti's picture

Have read all of the posts. Very interesting and much better disciplined than most sessions. and thank you for information.

Plug-in For MS Office

W^L+'s picture

Instead of the ODF-Converter project on SourceForge, with its well-known flaws (cannot set ODF formats as default formats for MS Office, poor fidelity between original file and the imported/exported version, ODF placed in separate submenu instead of the usual file->save as, and intermediate saves still require long export process), I'd recommend Sun's plugin for MS Office. It features much better integration with MS Office and better fidelity import/export.

Either one will trigger warnings about the format not being fully compatible, but for most purposes, ODF is fully-capable of representing MS Office data.

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