| 5 bootstrap.inc | variable_del($name) |
| 6 bootstrap.inc | variable_del($name) |
| 7 bootstrap.inc | variable_del($name) |
| 8 bootstrap.inc | variable_del($name) |
Unsets a persistent variable.
Case-sensitivity of the variable_* functions depends on the database collation used. To avoid problems, always use lower case for persistent variable names.
Parameters
$name: The name of the variable to undefine.
See also
variable_get(), variable_set()
File
- includes/
bootstrap.inc, line 634 - Functions that need to be loaded on every Drupal request.
Code
<?php
function variable_del($name) {
global $conf;
db_query("DELETE FROM {variable} WHERE name = '%s'", $name);
cache_clear_all('variables', 'cache');
unset($conf[$name]);
}
?>
Comments
delete multiple variables with one call
It would be nice to be able to call this like unset(), passing n parameters and having them all deleted instead of making successive calls to the function for each variable.
Or even something like
<?php
function variable_contains_del($name) {
global $conf;
db_query("DELETE FROM {variable} WHERE name like '%%%s%%'", $name);
cache_clear_all('variables', 'cache');
unset($conf[$name]);
}
?>
and the same thing for variable_beginswith_del (like '%s%%') and variable_endswith_del (like '%%%s')
Not sure about the escaped percents within single quotes, but this conveys the idea.
I saw this in the AddThis
I saw this in the AddThis module. Be sure to use the hook_uninstall function and replace addthis_% with your own module variable setting.
<?php// Remove module variables.
$result = db_query("SELECT name FROM {variable} WHERE name LIKE 'addthis_%'");
while ($var_name = db_result($result)) {
variable_del($var_name);
}
?>
Hitting the database to find
Hitting the database to find all your variables isn't necessary. You can use the global
$confvariable.<?phpglobal $conf;
foreach (array_keys($conf) as $key) {
// It's important to use === instead of == with strpos()
if (strpos($key, 'addthis_') === 0) {
variable_del($key);
}
}
?>
This is an approach I've used in various modules. It's lazy, but it hasn't failed me yet.
If you're removing all the
If you're removing all the variables set by your module in the uninstall function, it's much more efficient to do the following, since it saves multiple function calls and only clears the cache at the end.
The second db_query is the same one cache_clear_all('variables', 'cache'); makes, but without the overhead of a loop or additional wrapper functions.
<?php
function addthis_uninstall() {
// ... other code ...
db_query("DELETE FROM {variable} WHERE name LIKE 'addthis\_%'");
db_query("DELETE FROM {cache} WHERE cid='variables'");
}
?>