function nodeapi_example_nodeapi

Implementation of hook_nodeapi().

We will implement several node API operations here. This hook allows us to act on all major node operations, so we can manage our additional data appropriately.

Related topics

File

nodeapi_example/nodeapi_example.module, line 77

Code

function nodeapi_example_nodeapi(&$node, $op, $teaser, $page) {
    switch ($op) {
        // When the content editing form is submitted, we need to validate the input
        // to make sure the user made a selection, since we are requiring the rating
        // field. We have to check that the value has been set to avoid showing an
        // error message when a new blank form is presented. Calling form_set_error()
        // when the field is set but zero ensures not only that an error message is
        // presented, but also that the user must correct the error before being able
        // to submit the node.
        case 'validate':
            if (variable_get('nodeapi_example_' . $node->type, TRUE)) {
                if (isset($node->nodeapi_example_rating) && !$node->nodeapi_example_rating) {
                    form_set_error('nodeapi_example_rating', t('You must rate this content.'));
                }
            }
            break;
        // Now we need to take care of loading one of the extended nodes from the
        // database. An array containing our extra field needs to be returned.
        case 'load':
            // we match against vid in order to keep up with the current revision
            $rating = db_result(db_query('SELECT rating FROM {nodeapi_example} WHERE vid = %d', $node->vid));
            return array(
                'nodeapi_example_rating' => $rating,
            );
            break;
        // Insert is called after the node has been validated and saved to the
        // database. It gives us a chance to create our own record in the database.
        case 'insert':
            if (variable_get('nodeapi_example_' . $node->type, 0)) {
                db_query('INSERT INTO {nodeapi_example} (nid, vid, rating) VALUES (%d, %d, %d)', $node->nid, $node->vid, $node->nodeapi_example_rating);
            }
            break;
        // Update is called when an existing node has been changed. Here, we use a
        // DELETE then an INSERT rather than an UPDATE. The reason is that a node
        // created before this module was installed won't already have a rating
        // saved so there would be nothing to update.
        case 'update':
            if (variable_get('nodeapi_example_' . $node->type, 0)) {
                db_query('DELETE FROM {nodeapi_example} WHERE vid = %d', $node->vid);
                db_query('INSERT INTO {nodeapi_example} (nid, vid, rating) VALUES (%d, %d, %d)', $node->nid, $node->vid, $node->nodeapi_example_rating);
            }
            break;
        // Delete is called when the node is being deleted, it gives us a chance
        // to delete the rating too.
        // This will delete all revisions as well.
        case 'delete':
            db_query('DELETE FROM {nodeapi_example} WHERE nid = %d', $node->nid);
            break;
        // When a node revision is deleted, we need to remove the corresponding
        // record from our table. The only way to handle revision deletion is by
        // implementing hook_nodeapi().
        case 'delete revision':
            // Notice that we're matching a single revision based on the node's vid.
            db_query('DELETE FROM {nodeapi_example} WHERE vid = %d', $node->vid);
            break;
        // Finally, we need to take care of displaying our rating when the node is
        // viewed. This operation is called after the node has already been prepared
        // into HTML and filtered as necessary, so we know we are dealing with an
        // HTML teaser and body. We will inject our additional information at the front
        // of the node copy.
        //
        // Using nodeapi('view') is more appropriate than using a filter here, because
        // filters transform user-supplied content, whereas we are extending it with
        // additional information.
        case 'view':
            if (variable_get('nodeapi_example_' . $node->type, 0)) {
                $node->content['nodeapi_example'] = array(
                    '#value' => theme('nodeapi_example_rating', $node->nodeapi_example_rating),
                    '#weight' => -1,
                );
            }
            break;
    }
}