How to list categories in a container using views module

Thanks for the quick reply!
I first tried with a single '=' as operator and it let me save the filter field value.

Also, the argument for category ID was picked up by category_views inmediately.
It wasn't working for me because category legacy was missing during category creation
(taxonomy terms still shows 'uncategorized' in the test site).

Edit:
I don't know if these codes are enough for a patch.
The next step would be a container ID argument.

thank you Somebody for sharing this code ;)

I am actually using a couple of "tricks" that let me do what we need:

1. the first one is to create a list of *all* my categories (Filters: Node: Type is one of Category), then filter down only the categories promoted to front page (Filters: Node: Front Page equals Yes) and of course set the publishing status of all the categories i want to output to "Promoted to front page".

2. the other method (probably more usefull if you want to create various lists of categories from different containers) is to create a CCK content-type (can be empty also) and assign it to a particular container with the category_transform.module that you find in the Category package (needed in order to make the trick work!). Then you can simply filter by that "categorized" content type, and all your corresponding categories will be listed.

Of course these are "trickeries" more than solutions, so the code above should be proposed as a patch to core Category so to make it list categories in Views out of the box. Maybe you already did?

Cheers!

pardon my doubt, but:

a. how do you put togheter the two pieces of code above and the patch that can be found in the Category issue queue at http://drupal.org/project/comments/add/57821 ?

b. will this let me set a "Argument: Category Hierarchy: Distant Parent" for dynamically outputting nodes listed under distant children categories?

I'm actually looking for someone with enough Category+Views skills to do this, if interested please drop me a line. Of course the results will be available to the community.

thanks!

using the code in the comment below and setting category id as argument.

http://drupal.org/node/85984#comment-178189

Thanks to SomebodySysop for his excellent code! Since we are using both Taxonomy and Categories on our site for some reasons, we're unable to install the "taxonomy wrapper", and so I really needed the patch.

I had some minor problems, probably caused by my inaccurate work while editing the files, but finally it works. But however, I consulted the Views API documentation, and made my own revision, which I believe is better for our site: For the sake of keeping things tidy and scripts short I removed the advanced "category-and container-relations stuff", which is unnecessary at our site (as well as many others I believe), and I also added the link-functionality to the category-description field, so that your views may really link to full lists of the categories, instead of just showing the names.

Emdedded views on category-pages step-by-step (on Drupal 4.7.3. with Category 1.118 - don't know about other versions, but it might work also):

--- Add the category-functionality to Views, by placing a brand new file "views_category.inc" into the "(your_site)/modules/views/modules", which I believe is easier and safer than editing any existing files. The content of this new file is:

<?php
//
// Here is where we expose category table to views
//
function category_views_tables() {

  return array(
    'category_node' => array(
      'name' => 'category_node',
      'join' => array(
        'type' => 'inner',
        'left' => array(
          'table' => 'node',
          'field' => 'nid',
        ),
        'right' => array(
          'field' => 'nid',
        ), // end right array
      ), // end join array

      'fields' => array(
        'cid' => array(
          'name' => t('Category ID'),
          'sortable' => true
         ), // end cid array
       ), // end fields array

      'filters' => array(
        'cid' => array(
          'name' => t('Category ID'),
          'operator' => 'category_handler_operator_eqto',
          'help' => t('This filter allows to filter by category IDs.'),
          'value' => 'integer'
        ), // end cid array
  ), // end filters
    ), // end category_node array
    
    'category' => array(
      'name' => 'category',
      'join' => array(
        'type' => 'inner',
        'left' => array(
          'table' => 'category_node',
          'field' => 'cid',
        ),
        'right' => array(
          'field' => 'cid',
        ), // end right array
      ), // end join array

      'fields' => array(
        'description' => array(
          'name' => t('Category: Description'),
          'handler' => array(
            'category_hand_fld_desc_lnk'   => t('With link'),
            'category_hand_fld_desc_nolnk' => t('Not a link')
           ),
          'addlfields' => array('cid'),
          'sortable' => true
         ) // end description array
       ), // end fields array

      'filters' => array(
        'cnid' => array(
          'name' => t('Container: ID'),
          'operator' => 'category_handler_operator_eqto',
          'help' => t('This filter allows to filter by container-ID.'),
          'value' => 'integer'
        ), // end cnid array
  ), // end filters

      'sorts' => array(
       'description' => array(
       'name' => 'Category: Description',
       'help' => t('Sorts by category description.')
) // end description array
      ) // end sorts array

), // end category

  ); // end return array
}



function category_views_arguments() {
  $args = array(
    'cid' => array(
      'name' => t("Category ID"),
      'handler' => 'category_handler_arg_cid',
      'help' => t('This argument filters for a given Category ID'),
      )
    );
  return $args;
}


function category_handler_arg_cid($op, &$query, $argtype, $arg = '') {
  switch($op) {
    case 'summary':
      $query->ensure_table('category');
      $query->add_field('description', 'category');
      $query->add_field('cid', 'category');
      $fieldinfo['field'] = "category.description";
      return $fieldinfo;
    case 'sort':
      $query->add_orderby('category', 'description', $argtype);
      break;
    case 'filter':
      $query->ensure_table('category_node');
      $query->add_where('category_node.cid = '.$arg);
      $query->set_distinct();
      break;
    case 'link':
      return l($query->description, "$arg/" . intval($query->cid));
    case 'title':
      $result = db_query("SELECT description FROM {category} WHERE cid = %d", $query);
      $voc = db_fetch_object($result);
      return check_plain($voc->description);
  }
}

/**
*  Category-description as link (or not) handlers
*/

function category_hand_fld_desc_lnk($fieldinfo, $fielddata, $value, $data) {
  return l($value, "node/$data->category_cid");
}

function category_hand_fld_desc_nolnk($fieldinfo, $fielddata, $value, $data) {
  return check_plain($value);
}


/**
* A list of options to be used in equal to queries
*/
function category_handler_operator_eqto() {
  return array('=' => t('Is Equal To'), 'not' => t('Is NOT Equal To'));
}

?>

--- Empty your cache by deleting all the content from table named "drup_cache" (or something like that depending on your installation), executing the MySQL query along the lines "DELETE FROM `drup_cache` WHERE 1", from the PhpMyAdmin for example. Only then the new functionality will show up.

--- Go to "administer views" and create a new view, providing a page-view with all the fields, filters and sorts as you like, the way your category-pages should look like. In the "Arguments" field, add argument called "Category ID" - otherwise your category pages will display all nodes, and not only chosen category! The default field may be left as is ("return page not found") since this never happens and is most safe option. Save your new view.

--- Go to the edit-page on container, where you are going to emded the view onto all category-pages. Under "category view settings" select your new view, and save the container. You might also want to turn off the display of "prev/up/next" links, if you don't like them on the top of your view.

--- If you like to use some Exposed filters on this embedded view (to allow users custom filtering of nodes, like we did on our site here), you'll probably encounter the problem, that after changing and submitting the filters your users end up on the view's page only, without being embedded in the category and limited to its nodes (or even a "page not found"). That's a bug in the views module, which may be corrected by this small patch (sorry, I didn't have time to search if there is another patch for this around this massive forum, so I wrote my own). In "(your_site)/modules/views", in the file "views.module", under the function "views_filters_form" I changed the last bit this way:

  $form['#method'] = 'get';
  $oldurl = $_GET['q'];

  $form['#action'] = url($oldurl, NULL, NULL, true);

  $form['#process'] = array('views_filters_process' => array());

  $form['view'] = array('#type' => 'value', '#value' => $view);

  $form['submit'] = array('#type' => 'button', '#name' => '', '#value' => t('Use filter'));

    // clean URL get forms breaks if we don't give it a 'q'.

    if (!(bool)variable_get('clean_url', '0')) {

      $form['q'] = array(

        '#type' => 'hidden',

        '#value' => $oldurl,

        '#name' => 'q',

      );

    }



  return $form;

}

This patch ensures, that the form-submit URL is always a mirror of the actual page the view is embedded on, so the Exposed filters don't drop off from Categories. Note that we don't use Clean URLs on our site, so I can't check if the patch is okay also in that case! Also note that I changed the text on Submit button, to be different from submitting articles - I just needed to have different labels in the Czech locale for "submitting content" and "searching", which was impossible with identical English originals.

--- Another problem with exposed filters is, that the selectors are always styled as a table, which means they always stay in one horizontal line. That makes your page extremely wide (when there is a lot of exposed fileters, that is), forcing your users to scroll horizontally to find the submit-button. If you like to style the selectors as floats (to reflect variable widths of a resizable browser-window, like I did), you might like to include another patch into the views.module file - pretty close below the previous patch, replace this function:

function theme_views_filters($form) {

  $view = $form['view']['#value'];



  foreach ($view->exposed_filter as $count => $expose) {
    $veci[] = '<div class="xf-label">' . $expose['label'] . '</div>' .
          form_render($form["op$count"]) . form_render($form["filter$count"]);

  }

  $veci[] = form_render($form['submit']);



  // make the 'q' come first

  return form_render($form['q']) . theme('item_list', $veci) . form_render($form) .
    '<br style="clear:left"/>';

}

Now the selectors are not a table, but a simple item-list, allowing you to do whatever you like (in your theme's CSS). You might like to add some DIV with a CSS-class around the "theme('item_list', $veci)" if necessary, or change the final "clear:left", which I needed just to tune my graphics more than my theme can do.

--- You can also add a new field "Category description" to any of your views, to show categories your nodes belong to. But beware, that this field shows just ONE of the categories possibly assigned to a node, plus maybe (unless the filter "Node: distinct" is used) you'll get multiple occurences of the same node where more categories are assingned. You can also choose whether or not the category-description field links to the actual category - this is a brand new functionality, as compared to the SomebodySysop's code above. Another thing to keep in mind is, that for the sake of reducing the MySQL load, this is NOT the actual category title! So you should insert some sensible names of your categories also into the "description" field under "category information" (on the category's edit-page), and this one will be shown in your views.

Hope that this post might help someone to get the whole thing working without extensive searchs in this forum.

had numerous issues with 5.x-1.1, so I had to re-install 5.x-1.0 - and this code works fine.