Tools and tips for switching CMS

Question

I work for a university, and in the past year we finally broke away from our static HTML site of several thousand pages and moved to a Drupal site. This obviously entails massive amounts of data entry.

What if you're already using a CMS and are switching to another one that better suits your needs? How do you minimize the mountain of data entry during such a huge change? Are there tools built for this, or some best practices one should follow?

Answer 1

The Migrate module for Drupal would provide a big help. The Economist.com data migration to Drupal will give you an overview of the process.

The video from the Migration: not just for the birds presentation at Drupalcon DC 2009 is probably somewhat out-of-date, but also gives a good introduction.

Answer 2

• Expect to have to both pre-process and post-process your data manually, whatever happens. Accept early on that your data is likely to be in a worse state than you think it is: fields will be misused; record-to-record references (foreign keys) might not be implemented properly, or at all; content is likely to need weeding and occasionally to be just bad or incorrect.

• Check your database encoding. Older databases won't be in Unicode encodings, and get grumpy if you have to export data dumps and import them elsewhere. Even then, assume that there'll be some wacky nonprintable characters in your data: programs like Word seem to somehow inject them everywhere, and I've seen... codepoints... you people wouldn't believe. Consider sweeping your data before you even start (or even sweeping a database dump) for these characters. Decide whether or not to junk them or try to convert them in the case of e.g. Word "smart" punctuation characters.

• It's very difficult to create explicit data structures from implied one. If your incoming data has a separate date field, you can map that to a date field; if it has a date as part of a big lump of HTML, even if that date is in a tag with an id attribute, simple scripting won't work. You could use offline scripting with BeautifulSoup or (if your HTML's a bit nicer) the faster lxml to pre-process your data set, extract those implicit fields, and save them into an implicit format. Consider creating an intermediate database where these revisions are going to go.

• The Migrate module is excellent, but to get really good data fidelity and play more clever tricks you might need to learn about its hook system (Drupal's terminology for functions following a particular naming scheme) and the basics of writing a module to put these hooks in (a module is broadly just a PHP file where all the functions begin with the same text, the name of the module file.)

• All imported content should be flagged for at least a cursory check. You can do this by importing it with status=0 i.e. unpublished, and then create a view with the Views module to go through the content and open it in other tabs for checking. Views Bulk Operations lets you have a set of checkboxes alongside your view items, so you could approve many nodes at once.

• Expect to run and re-run and re-run the import, fixing new things every time. Check ten, or twenty items, as early as possible. If there are any problems, check ten or twenty more. Fix and repeat the import.

• Gauge how long a single import run is likely to take. Be pessimistic: we had an import we expected to take ten hours encounter exponential slowdown when we introduced the full data set; until we finally fixed some slow queries, it was projected to take two weeks.

• If in doubt, or if you think the technical aspects of the above are just going to take more time than the work itself, then just hire temps to do the data. But you still need decent quality controls, as early as possible during their work. Drupal developers are also for hire: try your country's relevant IRC channel, or post a note in a relevant groups.drupal.org group. They're more expensive than temps but they usually write better PHP...! Consider hiring an agency too: that's a shameless plug, as I work for one, but sometimes it's best to get experts in for these specific jobs.

• Really good imports are always hard, harder than you expect. Don't let it get you down!

Answer 3

Migrate + table wizard (and schema + views) is the way to go. With table wizard you can expose any table to drupal and map fields accordingly using migrate.

Look here for a detailed walktrough: http://www.lullabot.com/articles/drupal-data-imports-migrate-and-table-wizard

Answer 4

1. You'll want to have an access to existing data from django. This helps me a lot with migrating: http://docs.djangoproject.com/en/1.2/howto/legacy-databases/ . With correct model definitions you'll have full django power including the admin. In fact, I'm using django just as admin backend for several legacy php projects - django's admin can easily outachieve a lot of custom hand-written admin scripts.

2. Authorization should remain the same. Users should be able to login with their credentials but it is hard to write a migration script for auth data because password hashing schemas may be different and there is no way to convert between them without knowing plain passwords. Django provides a way to support different sources of auth so you can write Drupal auth backend: http://docs.djangoproject.com/en/1.2/topics/auth/#writing-an-authentication-backend

3. There is no need to do the full rewrite. If some parts are working fine they can still be powered by Drupal. New code can written using Django with same UI. Routing between old and new parts can be performed by web server url rewriting. Both django and drupal parts can be powered by the same DB.