ikiwiki/doc/tips/convert_mediawiki_to_ikiwiki.mdwn

[[!toc levels=2]]

Mediawiki is a dynamically-generated wiki which stores it's data in a
relational database. Pages are marked up using a proprietary markup. It is
possible to import the contents of a Mediawiki site into an ikiwiki,
converting some of the Mediawiki conventions into Ikiwiki ones.

The following instructions describe ways of obtaining the current version of
the wiki. We do not yet cover importing the history of edits.

Another set of instructions and conversion tools (which imports the full history)
can be found at <http://github.com/mithro/media2iki>

## Step 1: Getting a list of pages

The first bit of information you require is a list of pages in the Mediawiki.
There are several different ways of obtaining these.

### Parsing the output of `Special:Allpages`

Mediawikis have a special page called `Special:Allpages` which list all the
pages for a given namespace on the wiki.

If you fetch the output of this page to a local file with something like

    wget -q -O tmpfile 'http://your-mediawiki/wiki/Special:Allpages'

You can extract the list of page names using the following python script. Note
that this script is sensitive to the specific markup used on the page, so if
you have tweaked your mediawiki theme a lot from the original, you will need
to adjust this script too:

    import sys
    from xml.dom.minidom import parse, parseString
    
    dom = parse(sys.argv[1])
    tables = dom.getElementsByTagName("table")
    pagetable = tables[-1]
    anchors = pagetable.getElementsByTagName("a")
    for a in anchors:
        print a.firstChild.toxml().\
            replace('&amp;','&').\
            replace('&lt;','<').\
            replace('&gt;','>')

Also, if you have pages with titles that need to be encoded to be represented
in HTML, you may need to add further processing to the last line.

Note that by default, `Special:Allpages` will only list pages in the main
namespace. You need to add a `&namespace=XX` argument to get pages in a
different namespace. (See below for the default list of namespaces)

Note that the page names obtained this way will not include any namespace
specific prefix: e.g. `Category:` will be stripped off.

### Querying the database

If you have access to the relational database in which your mediawiki data is
stored, it is possible to derive a list of page names from this. With mediawiki's
MySQL backend, the page table is, appropriately enough, called `table`:

    SELECT page_namespace, page_title FROM page;

As with the previous method, you will need to do some filtering based on the
namespace.

### namespaces

The list of default namespaces in mediawiki is available from <http://www.mediawiki.org/wiki/Manual:Namespace#Built-in_namespaces>. Here are reproduced the ones you are most likely to encounter if you are running a small mediawiki install for your own purposes:

[[!table data="""
Index   | Name         | Example
0       | Main         | Foo
1       | Talk         | Talk:Foo
2       | User         | User:Jon
3       | User talk    | User_talk:Jon
6       | File         | File:Barack_Obama_signature.svg
10      | Template     | Template:Prettytable
14      | Category     | Category:Pages_needing_review
"""]]

## Step 2: fetching the page data

Once you have a list of page names, you can fetch the data for each page.

### Method 1: via HTTP and `action=raw`

You need to create two derived strings from the page titles: the
destination path for the page and the source URL. Assuming `$pagename` 
contains a pagename obtained above, and `$wiki` contains the URL to your
mediawiki's `index.php` file:

    src=`echo "$pagename" | tr ' ' _ | sed 's,&,&amp;,g'`
    dest=`"$pagename" | tr ' ' _ | sed 's,&,__38__,g'`
    
    mkdir -p `dirname "$dest"`
    wget -q "$wiki?title=$src&action=raw" -O "$dest"

You may need to add more conversions here depending on the precise page titles
used in your wiki.

If you are trying to fetch pages from a different namespace to the default,
you will need to prefix the page title with the relevant prefix, e.g.
`Category:` for category pages. You probably don't want to prefix it to the
output page, but you may want to vary the destination path (i.e. insert an
extra directory component corresponding to your ikiwiki's `tagbase`).

### Method 2: via HTTP and `Special:Export`

Mediawiki also has a special page `Special:Export` which can be used to obtain
the source of the page and other metadata such as the last contributor, or the
full history, etc.

You need to send a `POST` request to the `Special:Export` page. See the source
of the page fetched via `GET` to determine the correct arguments.

You will then need to write an XML parser to extract the data you need from
the result.

### Method 3: via the database

It is possible to extract the page data from the database with some
well-crafted queries.

## Step 3: format conversion

The next step is to convert Mediawiki conventions into Ikiwiki ones.

### categories

Mediawiki uses a special page name prefix to define "Categories", which
otherwise behave like ikiwiki tags. You can convert every Mediawiki category
into an ikiwiki tag name using a script such as

    import sys, re
    pattern =  r'\[\[Category:([^\]]+)\]\]'
    
    def manglecat(mo):
            return '\[[!tag %s]]' % mo.group(1).strip().replace(' ','_')
            
    for line in sys.stdin.readlines():
            res = re.match(pattern, line)
            if res:
                    sys.stdout.write(re.sub(pattern, manglecat, line))
            else: sys.stdout.write(line)

## Step 4: Mediawiki plugin

The [[plugins/contrib/mediawiki]] plugin can be used by ikiwiki to interpret
most of the Mediawiki syntax.

## External links

[[sabr]] used to explain how to [import MediaWiki content into
git](http://u32.net/Mediawiki_Conversion/index.html?updated), including full
edit history, but as of 2009/10/16 that site is not available. A copy of the 
information found on this website is stored at <http://github.com/mithro/media2iki>