nodeapi_example.module

<?php


/**
 * @file
 * This is an example outlining how a module can be used to extend existing
 * content types.
 *
 * We will add the ability for each node to have a "rating," which will be a
 * number from one to five.
 */

/**
 * @defgroup nodeapi_example Example: NodeAPI
 * @ingroup examples
 * @{
 * Modifying a node during its life-cycle. (drupal 6)
 *
 * This example demostrates 'piggy-backing' some data on the
 * node in another database table.
 *
 * This example is part of the Examples for Developers Project which you can download
 * and experiment with here: http://drupal.org/project/examples
 */

/**
 * Implementation of hook_form_alter().
 *
 * By implementing this hook, we're able to modify any form. We'll only make
 * changes to two types: a node's content type configuration and edit forms.
 *
 * We need to have a way for administrators to indicate which content types
 * should have our rating field added. This is done by inserting a checkbox in
 * the node's content type configuration page, in the 'Workflow' group.
 */
function nodeapi_example_form_alter(&$form, $form_state, $form_id) {
    if ($form_id == 'node_type_form' && isset($form['identity']['type'])) {
        // Alter the node type's configuration form to add our setting. We don't
        // need to worry about saving this value back to the variable, the form
        // we're altering will do it for us.
        $form['workflow']['nodeapi_example'] = array(
            '#type' => 'radios',
            '#title' => t('NodeAPI Example Rating'),
            '#default_value' => variable_get('nodeapi_example_' . $form['#node_type']->type, 0),
            '#options' => array(
                0 => t('Disabled'),
                1 => t('Enabled'),
            ),
            '#description' => t('Should this node have a rating attached to it?'),
        );
    }
    elseif (isset($form['type']) && isset($form['#node']) && $form['type']['#value'] . '_node_form' == $form_id) {
        // If the rating is enabled for this node type, we insert our control
        // into the form.
        $node = $form['#node'];
        if (variable_get('nodeapi_example_' . $form['type']['#value'], 0)) {
            // Note that $form['nodeapi_example_rating'] will become
            // $node->nodeapi_example_rating in hook_nodeapi validate op
            // This also means that if there is a fieldgroup defined,
            // $form['group']['field'], that it will become $node->field.
            $form['nodeapi_example_rating'] = array(
                '#type' => 'select',
                '#title' => t('Rating'),
                '#default_value' => isset($node->nodeapi_example_rating) ? $node->nodeapi_example_rating : '',
                '#options' => array(
                    0 => t('Unrated'),
                    1,
                    2,
                    3,
                    4,
                    5,
                ),
                '#required' => TRUE,
                '#weight' => 0,
            );
        }
    }
}

/**
 * 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.
 */
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;
    }
}

/**
 * Implementation of hook_theme().
 *
 * This lets us tell Drupal about our theme functions and their arguments.
 */
function nodeapi_example_theme() {
    return array(
        'nodeapi_example_rating' => array(
            'arguments' => array(
                'rating',
            ),
        ),
    );
}

/**
 * A custom theme function.
 *
 * By using this function to format our rating, themes can override this presentation
 * if they wish; for example, they could provide a star graphic for the rating. We
 * also wrap the default presentation in a CSS class that is prefixed by the module
 * name. This way, style sheets can modify the output without requiring theme code.
 */
function theme_nodeapi_example_rating($rating) {
    $options = array(
        0 => t('Unrated'),
        1 => t('Poor'),
        2 => t('Needs improvement'),
        3 => t('Acceptable'),
        4 => t('Good'),
        5 => t('Excellent'),
    );
    $output = '<div class="nodeapi_example_rating">';
    $output .= t('Rating: %rating', array(
        '%rating' => $options[(int) $rating],
    ));
    $output .= '</div>';
    return $output;
}

/**
 * @} End of "defgroup nodeapi_example".
 */