function nodeapi_example_uninstall

Implements hook_uninstall().

We need to clean up our variables data when uninstalling our module.

Our implementation of nodeapi_example_form_alter() automatically creates a nodeapi_example_node_type_<contentType> variable for each node type the user wants to rate.

To delete our variables we call variable_del for our variables' namespace, 'nodeapi_example_node_type_'. Note that an average module would have known variables that it had created, and it could just delete those explicitly. For example, see render_example_uninstall(). It's important not to delete variables that might be owned by other modules, so normally we would just explicitly delete a set of known variables.

hook_uninstall() will only be called when uninstalling a module, not when disabling a module. This allows our data to stay in the database if the user only disables our module without uninstalling it.

Related topics

Example: NodeAPI
Example using NodeAPI.

File

nodeapi_example/nodeapi_example.install, line 70

Code

function nodeapi_example_uninstall() {
    // Simple DB query to get the names of our variables.
    $results = db_select('variable', 'v')->fields('v', array(
        'name',
    ))
        ->condition('name', 'nodeapi_example_node_type_%', 'LIKE')
        ->execute();
    // Loop through and delete each of our variables.
    foreach ($results as $result) {
        variable_del($result->name);
    }
}