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
developer/examples/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.
*/
/**
* 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.
*/
function nodeapi_example_form_alter($form_id, &$form) {
// We're only modifying node forms, if the type field isn't set we don't need
// to bother; otherwise, store it for later retrieval.
if (isset($form['type'])) {
$type = $form['type']['#value'];
}
elseif (isset($form['orig_type'])) {
$type = $form['orig_type']['#value'];
}
else {
return;
}
// The rating is enabled on a per node type basis. The variable used to store
// this information is named named using both the name of this module, to
// avoid namespace conflicts, and the node type, because we support multiple node
// types.
$enabled = variable_get('nodeapi_example_' . $type, 0);
switch ($form_id) {
// 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. The variable will
// be automatically saved by the settings form.
case 'node_type_form':
$form['workflow']['nodeapi_example_' . $type] = array(
'#type' => 'radios',
'#title' => t('NodeAPI Example Rating'),
'#default_value' => $enabled,
'#options' => array(
0 => t('Disabled'),
1 => t('Enabled'),
),
'#description' => t('Should this node have a rating attached to it?'),
);
break;
case $type . '_node_form':
// If the rating is enabled for this node type, we insert our control
// into the form.
if ($enabled) {
$options = array(
0 => t('Unrated'),
1,
2,
3,
4,
5,
);
$form['nodeapi_example_rating'] = array(
'#type' => 'select',
'#title' => t('Rating'),
'#default_value' => $form['#node']->nodeapi_example_rating,
'#options' => $options,
'#required' => TRUE,
'#weight' => 0,
);
}
break;
}
}
/**
* Implementation of hook_nodeapi().
*
* We will implement several node API operations here. This hook allows us to
* act on all major node operations, so we can manage our additional data
* appropriately.
*/
function nodeapi_example_nodeapi(&$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':
$object = db_fetch_object(db_query('SELECT rating FROM {nodeapi_example} WHERE nid = %d', $node->nid));
return array(
'nodeapi_example_rating' => $object->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':
db_query('INSERT INTO {nodeapi_example} (nid, rating) VALUES (%d, %d)', $node->nid, $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':
db_query('DELETE FROM {nodeapi_example} WHERE nid = %d', $node->nid);
db_query('INSERT INTO {nodeapi_example} (nid, rating) VALUES (%d, %d)', $node->nid, $node->nodeapi_example_rating);
break;
// Delete is called whn the node is being deleted, it gives us a chance
// to delete the rating too.
case 'delete':
db_query('DELETE FROM {nodeapi_example} WHERE nid = %d', $node->nid);
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':
$node->content['nodeapi_example'] = array(
'#value' => theme('nodeapi_example_rating', $node->nodeapi_example_rating),
'#weight' => -1,
);
break;
}
}
/**
* A custom theme function.
*
* By using this function to format our rating, themes can override this presentation
* if they wish; for example, they could provide a star graphic for the rating. We
* also wrap the default presentation in a CSS class that is prefixed by the module
* name. This way, style sheets can modify the output without requiring theme code.
*/
function theme_nodeapi_example_rating($rating) {
$output = '<div class="nodeapi_example_rating">';
$options = array(
0 => t('Unrated'),
1 => t('Poor'),
2 => t('Needs improvement'),
3 => t('Acceptable'),
4 => t('Good'),
5 => t('Excellent'),
);
$output .= t('Rating: %rating', array(
'%rating' => $options[(int) $rating],
));
$output .= '</div>';
return $output;
}
Functions
Name | Description |
---|---|
nodeapi_example_form_alter | Implementation of hook_form_alter(). |
nodeapi_example_nodeapi | Implementation of hook_nodeapi(). |
theme_nodeapi_example_rating | A custom theme function. |