nodeapi_example.module in Examples for Developers 6
Same filename and directory in other branches
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.
File
nodeapi_example/nodeapi_example.moduleView source
<?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".
*/Functions
Name |
Description |
|---|---|
| nodeapi_example_form_alter | Implementation of hook_form_alter(). |
| nodeapi_example_nodeapi | Implementation of hook_nodeapi(). |
| nodeapi_example_theme | Implementation of hook_theme(). |
| theme_nodeapi_example_rating | A custom theme function. |