I am creating a custom module with its own schema of a few tables. These tables need to have some values pre-populated into them for the module to work (default locations, select options, etc).
What's the best practices way to insert default values into these tables during hook_install?
Since drupal_write_record is not available, I can use db_query, but I just want to make sure that I'm not breaking any cardinal rules by doing so.
The better way is to do it inside hook_enable(); at the time the hook is invoked, the module is already installed, and the schema of its database is available to Drupal, and to drupal_write_record(). As the hook is invoked all times a module is enabled, and not just when the module is installed, the hook implementation should check if it didn't added those database rows already (e.g., it should use a Drupal variable containing a boolean value).
As example of module that uses hook_enable() for a similar purpose, you can check forum_enable(), or php_enable() (which adds the "PHP code" input format).
function php_enable() {
$format_exists = (bool) db_query_range('SELECT 1 FROM {filter_format} WHERE name = :name', 0, 1, array(':name' => 'PHP code'))->fetchField();
// Add a PHP code text format, if it does not exist. Do this only for the
// first install (or if the format has been manually deleted) as there is no
// reliable method to identify the format in an uninstall hook or in
// subsequent clean installs.
if (!$format_exists) {
$php_format = array(
'format' => 'php_code',
'name' => 'PHP code',
// 'Plain text' format is installed with a weight of 10 by default. Use a
// higher weight here to ensure that this format will not be the default
// format for anyone.
'weight' => 11,
'filters' => array(
// Enable the PHP evaluator filter.
'php_code' => array(
'weight' => 0,
'status' => 1,
),
),
);
$php_format = (object) $php_format;
filter_format_save($php_format);
drupal_set_message(t('A <a href="@php-code">PHP code</a> text format has been created.', array('@php-code' => url('admin/config/content/formats/' . $php_format->format))));
}
}
As shown from those hook implementations, the code could necessarily need to be executed all times the hook is executed; it could also be the code needs to just executed once, as in the case the default values added to the database cannot be altered from the user, who doesn't have a user interface to alter/delete those values.
variable_set(), which are not deleted with variable_del(), are loaded in memory when Drupal bootstraps, and saved in a global variable; this means that they are in memory whatever the module is using those values, or not. Using a custom database table, you can be sure those values are only loaded when the module really needs it. You should not use variable_set() if the Drupal variable contains an array to which you keep adding a new array index all times, for example.
I'd go with db_query / db_insert (D6 / D7) in hook_install().
It's not considered bad practice (and nobody is ever forcing you to use drupal_write_record()).
It is not uncommon for people to disable and re-enable modules, and in that case your code in hook_enable() would fire each time. which is not nice.
