[development] important reminder: do not use API functions in update code

Sean Robertson seanr at ngpsoftware.com
Tue Dec 4 14:44:42 UTC 2007

So all modules should still use db_query for updates (as in 5.x) or does 
this only apply to core?

Gábor Hojtsy wrote:
> Hey,
> As more and more schema API functionality is added to Drupal, and as
> more and more database changes are made in each release, it is very
> important for you to remenber this:
>  **Avoid using API functions (ie. anything used in the Drupal runtime
> too) in your update functions**
> There were several instances of this before. Previous updates used
> node content type listing API functions, some of which were simply
> gone later, so no update-hopping (through multiple versions) was
> possible without some update code hacking. But it is just as easy to
> write bad code when in the same Drupal version. Take
> system_update_6027 for example, which we try to fix at
> http://drupal.org/node/197500 .
>  - it calls _block_rehash() (note the underscore, not even a public
> API function!)
>  - _block_rehash() uses drupal_save_record(), which uses the most up
> to date schema from system_schema()
> Now what happens if the schema is changed in a later update in Drupal
> 6? (ie. > 6027 but < 7000). Well, system_update_6027() becomes broken,
> because its _block_rehash() call tries to use the latest schema (as in
> after all Drupal 6 updates are run), but all Drupal 6 updates are not
> run yet.
> Think about this when you are doing your Drupal 6 upgrade functions
> for your modules.
> Gabor

Sean Robertson
Web Developer
NGP Software, Inc.
seanr at ngpsoftware.com
(202) 686-9330

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