How to zip a WordprocessingML folder into readable docx

Question

I have been trying to write a simple Markdown -> docx parser/writer, but am completely stuck with the last part, which should be the easiest: i.e. compressing the folder into a .docx that Word, or any other .docx reader, will recognize.

My parser-writer is irrelevant really: I have this problem if I simply unzip any old Word-produced *.docx and then try to recompress it with the usual compression utilities, giving it the file-ending docx. Is there some mysterious header I should be adding, or do I need a special OPC compression utility, or what?

I don't so much want a tool that will do this, as to figure out what is supposed to be there. It seems to be independent of the WordprocessingML specification.

Needless to say I don't know anything about compression. Everything I can find via Google has to do with fancy utilities you can use in business, but I'm making a little executable that would be GPLd or something, and should work on anything.

Eric White is exactly right in inferring that I experienced "the most common problem around manually zipping an Open XML document". The error is already visible in the title of the question: I was compressing a folder containing the material, rather than joining the materials severally into a zip file. It occurs to me I might have guessed this, since of course if you unzip a .docx file, you emphatically don't get a little directory, but files all over the directory you're acting in. Thanks! --Of course, this means I should get back to the project I mention above ... :) — applicative, Apr 24 '11 at 22:21

Eric White · Answer 1 · 2011-04-24T21:36:04.487

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The most common problem around manually zipping together Open XML documents is that it will not work if you zip the directory instead of the contents. In other words, the[content_types].xml file, and the word, docProps, and _rels directories need to reside at the root level of the zip file.

edited Apr 24 '11 at 21:36

answered Apr 22 '11 at 02:19

Eric White

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Hi, I am the original poster, but I lost this S.O. account, else I would mark this as the 'right answer'. You are right that my mistake was to zip the directory that included all the material, thinking I needed the right incantation, form of compression ... some subtlety. MSWord is quite willing to open the file if I accumulate all relevant files (including wholesale addition of subdirectories like `word` that are themselves at the root level.) to a single zip file. So far I have tried this on OS X without incident. I will study things more. – applicative Apr 24 '11 at 22:13
Truly open, self-made docx by WinZip and WinRAR are all readable! – Lei Yang Nov 15 '13 at 09:45

score 23 · Answer 2 · answered Apr 19 '13 at 13:28

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Here are steps to unzip my.docx and re-zip:

% mkdir unzipped
% cd unzipped/
% unzip ../my.docx    
% zip -r ../rezipped.docx *
% open ../rezipped.docx

answered Apr 19 '13 at 13:28

Sam Barnum

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score 3 · Answer 3 · answered Oct 06 '09 at 00:34

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The compression algorithm used is "Zip" (Base 64) compression.

7zip seems to offer this, though i have no tested it.

answered Oct 06 '09 at 00:34

Mica

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score 3 · Answer 4 · answered May 11 '10 at 09:15

Further to what Mica said, the contents of the ZIP file are organised according to the Open Packaging Convention; cf. Microsoft's Essentials of the Open Packaging Convention.

You can use the .NET System.IO.Packaging to make and manipulate .docx files; this class is implemented in the Mono project.

How to zip a WordprocessingML folder into readable docx

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