render_example.module in Examples for Developers 7

Demonstrates render arrays.

File

render_example/render_example.module

<?php

/**
 * @file
 * Demonstrates render arrays.
 */

/**
 * @defgroup render_example Example: Render
 * @ingroup examples
 * @{
 * Demonstrate how render arrays are arranged and how they can be altered.
 * This alters blocks and the page to show the actual render array
 * that is being used to create each item.
 *
 * @see drupal_render()
 */

// This allows drupal_var_export() to work.
require_once 'includes/utility.inc';

/**
 * Implements hook_menu().
 */
function render_example_menu() {
  $items['examples/render_example'] = array(
    'title' => 'Render Example',
    'page callback' => 'render_example_info',
    'access callback' => TRUE,
  );
  $items['examples/render_example/altering'] = array(
    'title' => 'Alter pages and blocks',
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'render_example_demo_form',
    ),
    'access arguments' => array(
      'access devel information',
    ),
  );
  $items['examples/render_example/arrays'] = array(
    'title' => 'Render array examples',
    'page callback' => 'render_example_arrays',
    'access callback' => TRUE,
  );
  return $items;
}

/**
 * Simple basic information about the module; an entry point.
 */
function render_example_info() {
  return t('The render example provides a <ul><li><a href="!arrays">demonstration of of render array usage</a></li><li><a href="!alter">using hook_page_alter()</a> to make various changes on a page.</li></ul>', array(
    '!arrays' => url('examples/render_example/arrays'),
    '!alter' => url('examples/render_example/altering'),
  ));
}

/**
 * Provides a number of render arrays and show what they do.
 *
 * Each array is keyed by a description; it's returned for rendering at page
 * render time. It's easy to add new examples to this.
 *
 * The array items in $demos are intended to be raw, normal render arrays
 * that can be experimented with to end up with different outcomes.
 */
function render_example_arrays() {

  // Interval in seconds for cache update with #cache.
  $interval = 60;
  $demos = array(
    // Demonstrate the simplest markup, a #markup element.
    t('Super simple #markup') => array(
      '#markup' => t('Some basic text in a #markup (shows basic markup and how it is rendered)'),
    ),
    // Shows how #prefix and #suffix can add markup into an array.
    t('Using #prefix and #suffix') => array(
      '#markup' => t('This one adds a prefix and suffix, which put a div around the item'),
      '#prefix' => '<div><br/>(prefix)<br/>',
      '#suffix' => '<br/>(suffix)</div>',
    ),
    // When #theme is provided, it is the #theme function's job to figure out
    // the meaning of the render array. The #theme function receives the entire
    // element in $variables and must return it, where it will be the content
    // of '#children'. When a #theme or other function is provided, custom
    // properties can be invented and used as needed, as the #separator
    // property provided here.
    //
    // If #theme is not provided, either explicitly or by the underlying
    // element, then the children are rendered using their own properties and
    // the results go into #children.
    t('theme for an element') => array(
      'child' => array(
        t('This is some text that should be put together'),
        t('This is some more text that we need'),
      ),
      // An element we've created which will be used by our theming function.
      '#separator' => ' | ',
      '#theme' => 'render_example_aggregate',
    ),
    // #theme_wrappers provides an array of theme functions which theme the
    // envelope or "wrapper" of a set of child elements. The theme function
    // finds its element children (the sub-arrays) already rendered in
    // '#children'.
    t('theme_wrappers demonstration') => array(
      'child1' => array(
        '#markup' => t('Markup for child1'),
      ),
      'child2' => array(
        '#markup' => t('Markup for child2'),
      ),
      '#theme_wrappers' => array(
        'render_example_add_div',
        'render_example_add_notes',
      ),
    ),
    // Add '#pre_render' and '#post_render' handlers.
    // - '#pre_render' functions get access to the array before it is rendered
    //   and can change it. This is similar to a theme function, but it is a
    //   specific fixed function and changes the array in place rather than
    //   rendering it..
    // - '#post_render' functions get access to the rendered content, but also
    //   have the original array available.
    t('pre_render and post_render') => array(
      '#markup' => '<div style="color:green">' . t('markup for pre_render and post_render example') . '</div>',
      '#pre_render' => array(
        'render_example_add_suffix',
      ),
      '#post_render' => array(
        'render_example_add_prefix',
      ),
    ),
    // Cache an element for $interval seconds using #cache.
    // The assumption here is that this is an expensive item to render, perhaps
    // large or otherwise expensive. Of course here it's just a piece of markup,
    // so we don't get the value.
    //
    // #cache allows us to set
    // - 'keys', an array of strings that will create the string cache key.
    // - 'bin', the cache bin
    // - 'expire', the expire timestamp. Note that this is actually limited
    //   to the granularity of a cron run.
    // - 'granularity', a bitmask determining at what level the caching is done
    //   (user, role, page).
    t('cache demonstration') => array(
      // If your expensive function were to be executed here it would happen
      // on every page load regardless of the cache. The actual markup is
      // added via the #pre_render function, so that drupal_render() will only
      // execute the expensive function if this array has not been cached.
      '#markup' => '',
      '#pre_render' => array(
        'render_example_cache_pre_render',
      ),
      '#cache' => array(
        'keys' => array(
          'render_example',
          'cache',
          'demonstration',
        ),
        'bin' => 'cache',
        'expire' => time() + $interval,
        'granularity' => DRUPAL_CACHE_PER_PAGE | DRUPAL_CACHE_PER_ROLE,
      ),
    ),
  );

  // The rest of this function just places the above arrays in a context where
  // they can be rendered (hopefully attractively and usefully) on the page.
  $page_array = array();
  foreach ($demos as $key => $item) {
    $page_array[$key]['#theme_wrappers'] = array(
      'render_array',
    );
    $page_array[$key]['#description'] = $key;
    $page_array[$key]['unrendered'] = array(
      '#prefix' => '<div class="unrendered-label">' . t('Unrendered array (as plain text and with a krumo version)') . ':</div>',
      '#type' => 'markup',
      '#markup' => htmlentities(drupal_var_export($item)),
    );
    $page_array[$key]['kpr'] = array(
      // The kpr() function is from devel module and is here only allow us
      // to output the array in a way that's easy to explore.
      '#markup' => kpr($item, TRUE),
    );
    $page_array[$key]['hr'] = array(
      '#markup' => '<hr/>',
    );
    $page_array[$key]['rendered'] = array(
      $item,
    );
    $page_array[$key]['rendered']['#prefix'] = '<p><em>Rendered version (light blue)</em>:</p>' . '<div class="rendered">';
    $page_array[$key]['rendered']['#suffix'] = '</div>';
  }
  return $page_array;
}

/**
 * A '#pre_render' function.
 *
 * @param array $element
 *   The element which will be rendered.
 *
 * @return array
 *   The altered element. In this case we add the #markup.
 */
function render_example_cache_pre_render($element) {
  $element['#markup'] = render_example_cache_expensive();

  // The following line is due to the bug described in
  // http://drupal.org/node/914792. A #markup element's #pre_render must set
  // #children because it replaces the default #markup pre_render, which is
  // drupal_pre_render_markup().
  $element['#children'] = $element['#markup'];
  return $element;
}

/**
 * A potentially expensive function.
 *
 * @return string
 *   Some demo text.
 */
function render_example_cache_expensive() {
  $interval = 60;
  $time_message = t('The current time was %time when this was cached. Updated every %interval seconds', array(
    '%time' => date('r'),
    '%interval' => $interval,
  ));

  // Uncomment the following line to demonstrate that this function is not
  // being run when the rendered array is cached.
  // drupal_set_message($time_message);
  return $time_message;
}

/**
 * A '#pre_render' function.
 *
 * @param array $element
 *   The element which will be rendered.
 *
 * @return array
 *   The altered element. In this case we add a #prefix to it.
 */
function render_example_add_suffix($element) {
  $element['#suffix'] = '<div style="color:red">' . t('This #suffix was added by a #pre_render') . '</div>';

  // The following line is due to the bug described in
  // http://drupal.org/node/914792. A #markup element's #pre_render must set
  // #children because it replaces the default #markup pre_render, which is
  // drupal_pre_render_markup().
  $element['#children'] = $element['#markup'];
  return $element;
}

/**
 * A '#post_render' function to add a little markup onto the end markup.
 *
 * @param string $markup
 *   The rendered element.
 * @param array $element
 *   The element which was rendered (for reference)
 *
 * @return string
 *   Markup altered as necessary. In this case we add a little postscript to it.
 */
function render_example_add_prefix($markup, $element) {
  $markup = '<div style="color:blue">This markup was added after rendering by a #post_render</div>' . $markup;
  return $markup;
}

/**
 * A #theme function.
 *
 * This #theme function has the responsibility of consolidating/rendering the
 * children's markup and returning it, where it will be placed in the
 * element's #children property.
 */
function theme_render_example_aggregate($variables) {
  $output = '';
  foreach (element_children($variables['element']['child']) as $item) {
    $output .= $variables['element']['child'][$item] . $variables['element']['#separator'];
  }
  return $output;
}

/*************** Altering Section **************************
 * The following section of the example builds and arranges the altering
 * example.
 */

/**
 * Builds the form that offers options of what items to show.
 */
function render_example_demo_form($form, &$form_state) {
  $form['description'] = array(
    '#type' => 'markup',
    '#markup' => t('This example shows what render arrays look like in the building of a page. It will not work unless the user running it has the "access devel information" privilege. It shows both the actual arrays used to build a page or block and also the capabilities of altering the page late in its lifecycle.'),
  );
  $form['show_arrays'] = array(
    '#type' => 'fieldset',
    '#title' => t('Show render arrays'),
  );
  foreach (array(
    'block',
    'page',
  ) as $type) {
    $form['show_arrays']['render_example_show_' . $type] = array(
      '#type' => 'checkbox',
      '#title' => t('Show @type render arrays', array(
        '@type' => $type,
      )),
      '#default_value' => variable_get('render_example_show_' . $type, FALSE),
    );
  }
  $form['page_fiddling'] = array(
    '#type' => 'fieldset',
    '#title' => t('Make changes on page via hook_page_alter()'),
  );
  $form['page_fiddling']['render_example_note_about_render_arrays'] = array(
    '#title' => t('Add a note about render arrays to top of sidebar_first (if it exists)'),
    '#description' => t('Creates a simple render array that displays the use of #pre_render, #post_render, #theme, and #theme_wrappers.'),
    '#type' => 'checkbox',
    '#default_value' => variable_get('render_example_note_about_render_arrays', FALSE),
  );
  $form['page_fiddling']['render_example_move_navigation_menu'] = array(
    '#title' => t('Move the navigation menu to the top of the content area'),
    '#description' => t('Uses hook_page_alter() to move the navigation menu into another region.'),
    '#type' => 'checkbox',
    '#default_value' => variable_get('render_example_move_navigation_menu', FALSE),
  );
  $form['page_fiddling']['render_example_reverse_sidebar'] = array(
    '#title' => t('Reverse ordering of sidebar_first elements (if it exists) - will affect the above'),
    '#description' => t('Uses hook_page_alter() to reverse the ordering of items in sidebar_first'),
    '#type' => 'checkbox',
    '#default_value' => variable_get('render_example_reverse_sidebar', FALSE),
  );
  $form['page_fiddling']['render_example_prefix'] = array(
    '#title' => t('Use #prefix and #suffix to wrap a div around every block'),
    '#description' => t('Uses hook_page_alter to wrap all blocks with a div using #prefix and #suffix'),
    '#type' => 'checkbox',
    '#default_value' => variable_get('render_example_prefix'),
  );
  return system_settings_form($form);
}

/**
 * Implements hook_page_alter().
 *
 * Alters the page in several different ways based on how the form has been
 * configured.
 */
function render_example_page_alter(&$page) {

  // Re-sort the sidebar in reverse order.
  if (variable_get('render_example_reverse_sidebar', FALSE) && !empty($page['sidebar_first'])) {
    $page['sidebar_first'] = array_reverse($page['sidebar_first']);
    foreach (element_children($page['sidebar_first']) as $element) {

      // Reverse the weights if they exist.
      if (!empty($page['sidebar_first'][$element]['#weight'])) {
        $page['sidebar_first'][$element]['#weight'] *= -1;
      }
    }
    $page['sidebar_first']['#sorted'] = FALSE;
  }

  // Add a list of items to the top of sidebar_first.
  // This shows how #theme and #theme_wrappers work.
  if (variable_get('render_example_note_about_render_arrays', FALSE) && !empty($page['sidebar_first'])) {
    $items = array(
      t('Render arrays are everywhere in D7'),
      t('Leave content unrendered as much as possible'),
      t('This allows rearrangement and alteration very late in page cycle'),
    );
    $note = array(
      '#title' => t('Render Array Example'),
      '#items' => $items,
      // The functions in #pre_render get to alter the actual data before it
      // gets rendered by the various theme functions.
      '#pre_render' => array(
        'render_example_change_to_ol',
      ),
      // The functions in #post_render get both the element and the rendered
      // data and can add to the rendered data.
      '#post_render' => array(
        'render_example_add_hr',
      ),
      // The #theme theme operation gets the first chance at rendering the
      // element and its children.
      '#theme' => 'item_list',
      // Then the theme operations in #theme_wrappers can wrap more around
      // what #theme left in #chilren.
      '#theme_wrappers' => array(
        'render_example_add_div',
        'render_example_add_notes',
      ),
      '#weight' => -9999,
    );
    $page['sidebar_first']['render_array_note'] = $note;
    $page['sidebar_first']['#sorted'] = FALSE;
  }

  // Move the navigation menu into the content area.
  if (variable_get('render_example_move_navigation_menu', FALSE) && !empty($page['sidebar_first']['system_navigation']) && !empty($page['content'])) {
    $page['content']['system_navigation'] = $page['sidebar_first']['system_navigation'];
    $page['content']['system_navigation']['#weight'] = -99999;
    unset($page['content']['#sorted']);
    unset($page['sidebar_first']['system_navigation']);
  }

  // Show the render array used to build the page render array display.
  if (variable_get('render_example_show_page', FALSE)) {
    $form['render_example_page_fieldset'] = array(
      '#type' => 'fieldset',
      '#title' => t('Page render array'),
      '#collapsible' => TRUE,
      '#collapsed' => TRUE,
    );
    $form['render_example_page_fieldset']['markup'] = array(
      // The kpr() function is from devel module and is here only allow us
      // to output the array in a way that's easy to explore.
      '#markup' => kpr($page, TRUE),
    );
    $page['content']['page_render_array'] = drupal_get_form('render_example_embedded_form', $form);
    $page['content']['page_render_array']['#weight'] = -999999;
    $page['content']['#sorted'] = FALSE;
  }

  // Add render array to the bottom of each block.
  if (variable_get('render_example_show_block', FALSE)) {
    foreach (element_children($page) as $region_name) {
      foreach (element_children($page[$region_name]) as $block_name) {

        // Push the block down a level so we can add another block after it.
        $old_block = $page[$region_name][$block_name];
        $page[$region_name][$block_name] = array(
          $block_name => $old_block,
        );
        $form = array();
        $form['render_example_block_fieldset'] = array(
          '#type' => 'fieldset',
          '#title' => t('Block render array'),
          '#collapsible' => TRUE,
          '#collapsed' => TRUE,
        );
        $form['render_example_block_fieldset']['markup'] = array(
          '#type' => 'item',
          '#title' => t('%blockname block render array', array(
            '%blockname' => $block_name,
          )),
          // The kpr() function is from devel module and is here only allow us
          // to output the array in a way that's easy to explore.
          '#markup' => kpr($old_block, TRUE),
        );

        // Add the new block that contains the render array.
        $page[$region_name][$block_name]['render_example_block_render_array'] = drupal_get_form('render_example_embedded_form', $form);
        $page[$region_name][$block_name]['render_example_block_render_array']['#weight'] = 999;
      }
    }
  }

  // Add #prefix and #suffix to a block to wrap a div around it.
  if (variable_get('render_example_prefix', FALSE)) {
    foreach (element_children($page) as $region_name) {
      foreach (element_children($page[$region_name]) as $block_name) {
        $block =& $page[$region_name][$block_name];
        $block['#prefix'] = '<div class="block-prefix"><p>Prefixed</p>';
        $block['#suffix'] = '<span class="block-suffix">Block suffix</span></div>';
      }
    }
  }
}

/**
 * Utility function to build a named form given a set of form elements.
 *
 * This is a standard form builder function that takes an additional array,
 * which is itself a form.
 *
 * @param array $form
 *   Form API form array.
 * @param array $form_state
 *   Form API form state array.
 * @param array $form_items
 *   The form items to be included in this form.
 */
function render_example_embedded_form($form, &$form_state, $form_items) {
  return $form_items;
}

/**
 * Implements hook_theme().
 */
function render_example_theme() {
  $items = array(
    'render_example_add_div' => array(
      'render element' => 'element',
    ),
    'render_example_add_notes' => array(
      'render element' => 'element',
    ),
    'render_array' => array(
      'render element' => 'element',
    ),
    'render_example_aggregate' => array(
      'render element' => 'element',
    ),
  );
  return $items;
}

/**
 * Wraps a div around the already-rendered #children.
 */
function theme_render_example_add_div($variables) {
  $element = $variables['element'];
  $output = '<div class="render-example-wrapper-div">';
  $output .= $element['#children'];
  $output .= '</div>';
  return $output;
}

/**
 * Wraps a div and add a little text after the rendered #children.
 */
function theme_render_example_add_notes($variables) {
  $element = $variables['element'];
  $output = '<div class="render-example-notes-wrapper-div">';
  $output .= $element['#children'];
  $output .= '<em>' . t('This is a note added by a #theme_wrapper') . '</em>';
  $output .= '</div>';
  return $output;
}

/**
 * Themes the render array (from the demonstration page).
 */
function theme_render_array($variables) {
  $heading = '<div class="render-header">' . $variables['element']['#description'] . '</div>';
  $rendered = '<div class="render-array">' . $heading . $variables['element']['#children'] . '</div>';
  return $rendered;
}

/**
 * Adds a #type to the element before it gets rendered.
 *
 * In this case, changes from the default 'ul' to 'ol'.
 *
 * @param array $element
 *   The element to be altered, in this case a list, ready for theme_item_list.
 *
 * @return array
 *   The altered list (with '#type')
 */
function render_example_change_to_ol($element) {
  $element['#type'] = 'ol';
  return $element;
}

/**
 * Alter the rendered output after all other theming.
 *
 * This #post_render function gets to alter the rendered output after all
 * theme functions have acted on it, and it receives the original data, so
 * can make decisions based on that. In this example, no use is made of the
 * passed-in $element.
 *
 * @param string $markup
 *   The already-rendered data
 * @param array $element
 *   The data element that was rendered
 *
 * @return string
 *   The altered data.
 */
function render_example_add_hr($markup, $element) {
  $output = $markup . '<hr />';
  return $output;
}

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

Functions

Name	Description
render_example_add_hr	Alter the rendered output after all other theming.
render_example_add_prefix	A '#post_render' function to add a little markup onto the end markup.
render_example_add_suffix	A '#pre_render' function.
render_example_arrays	Provides a number of render arrays and show what they do.
render_example_cache_expensive	A potentially expensive function.
render_example_cache_pre_render	A '#pre_render' function.
render_example_change_to_ol	Adds a #type to the element before it gets rendered.
render_example_demo_form	Builds the form that offers options of what items to show.
render_example_embedded_form	Utility function to build a named form given a set of form elements.
render_example_info	Simple basic information about the module; an entry point.
render_example_menu	Implements hook_menu().
render_example_page_alter	Implements hook_page_alter().
render_example_theme	Implements hook_theme().
theme_render_array	Themes the render array (from the demonstration page).
theme_render_example_add_div	Wraps a div around the already-rendered #children.
theme_render_example_add_notes	Wraps a div and add a little text after the rendered #children.
theme_render_example_aggregate	A #theme function.