root/trunk/wp-includes/taxonomy.php

<?php
/**
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 */

//
// Taxonomy Registration
//

/**
 * Default Taxonomy Objects
 * @since 2.3
 * @global array $wp_taxonomies
 */
$wp_taxonomies = array();
$wp_taxonomies['category'] = (object) array('name' => 'category', 'object_type' => 'post', 'hierarchical' => true, 'update_count_callback' => '_update_post_term_count');
$wp_taxonomies['post_tag'] = (object) array('name' => 'post_tag', 'object_type' => 'post', 'hierarchical' => false, 'update_count_callback' => '_update_post_term_count');
$wp_taxonomies['link_category'] = (object) array('name' => 'link_category', 'object_type' => 'link', 'hierarchical' => false);

/**
 * get_object_taxonomies() - Return all of the taxonomy names that are of $object_type
 *
 * It appears that this function can be used to find all of the names inside of
 * $wp_taxonomies global variable.
 *
 * <code><?php $taxonomies = get_object_taxonomies('post'); ?></code>
 * Should result in <code>Array('category', 'post_tag')</code>
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses $wp_taxonomies
 *
 * @param array|string|object $object Name of the type of taxonomy object, or an object (row from posts)
 * @return array The names of all taxonomy of $object_type.
 */
function get_object_taxonomies($object) {
    global $wp_taxonomies;

    if ( is_object($object) ) {
        if ( $object->post_type == 'attachment' )
            return get_attachment_taxonomies($object);
        $object = $object->post_type;
    }

    $object = (array) $object;

    $taxonomies = array();
    foreach ( $wp_taxonomies as $taxonomy ) {
        if ( array_intersect($object, (array) $taxonomy->object_type) )
            $taxonomies[] = $taxonomy->name;
    }

    return $taxonomies;
}

/**
 * get_taxonomy() - Returns the taxonomy object of $taxonomy.
 *
 * The get_taxonomy function will first check that the parameter string given
 * is a taxonomy object and if it is, it will return it.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses $wp_taxonomies
 * @uses is_taxonomy() Checks whether taxonomy exists
 *
 * @param string $taxonomy Name of taxonomy object to return
 * @return object|bool The Taxonomy Object or false if $taxonomy doesn't exist
 */
function get_taxonomy( $taxonomy ) {
    global $wp_taxonomies;

    if ( ! is_taxonomy($taxonomy) )
        return false;

    return $wp_taxonomies[$taxonomy];
}

/**
 * is_taxonomy() - Checks that the taxonomy name exists
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses $wp_taxonomies
 *
 * @param string $taxonomy Name of taxonomy object
 * @return bool Whether the taxonomy exists or not.
 */
function is_taxonomy( $taxonomy ) {
    global $wp_taxonomies;

    return isset($wp_taxonomies[$taxonomy]);
}

/**
 * is_taxonomy_hierarchical() - Whether the taxonomy object is hierarchical
 *
 * Checks to make sure that the taxonomy is an object first. Then Gets the object, and finally
 * returns the hierarchical value in the object.
 *
 * A false return value might also mean that the taxonomy does not exist.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses is_taxonomy() Checks whether taxonomy exists
 * @uses get_taxonomy() Used to get the taxonomy object
 *
 * @param string $taxonomy Name of taxonomy object
 * @return bool Whether the taxonomy is hierarchical
 */
function is_taxonomy_hierarchical($taxonomy) {
    if ( ! is_taxonomy($taxonomy) )
        return false;

    $taxonomy = get_taxonomy($taxonomy);
    return $taxonomy->hierarchical;
}

/**
 * register_taxonomy() - Create or modify a taxonomy object. Do not use before init.
 *
 * A simple function for creating or modifying a taxonomy object based on the parameters given.
 * The function will accept an array (third optional parameter), along with strings for the
 * taxonomy name and another string for the object type.
 *
 * Nothing is returned, so expect error maybe or use is_taxonomy() to check whether taxonomy exists.
 *
 * Optional $args contents:
 * hierarachical - has some defined purpose at other parts of the API and is a boolean value.
 * update_count_callback - works much like a hook, in that it will be called when the count is updated.
 * rewrite - false to prevent rewrite, or array('slug'=>$slug) to customize permastruct; default will use $taxonomy as slug
 * query_var - false to prevent queries, or string to customize query var (?$query_var=$term); default will use $taxonomy as query var
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 * @uses $wp_taxonomies Inserts new taxonomy object into the list
 * @uses $wp_rewrite Adds rewrite tags and permastructs
 * @uses $wp Adds query vars
 *
 * @param string $taxonomy Name of taxonomy object
 * @param array|string $object_type Name of the object type for the taxonomy object.
 * @param array|string $args See above description for the two keys values.
 */
function register_taxonomy( $taxonomy, $object_type, $args = array() ) {
    global $wp_taxonomies, $wp_rewrite, $wp;

    $defaults = array('hierarchical' => false, 'update_count_callback' => '', 'rewrite' => true, 'query_var' => true);
    $args = wp_parse_args($args, $defaults);

    if ( false !== $args['query_var'] && !empty($wp) ) {
        if ( empty($args['query_var']) )
            $args['query_var'] = $taxonomy;
        $args['query_var'] = sanitize_title_with_dashes($args['query_var']);
        $wp->add_query_var($args['query_var']);
    }

    if ( false !== $args['rewrite'] && !empty($wp_rewrite) ) {
        if ( !is_array($args['rewrite']) )
            $args['rewrite'] = array();
        if ( !isset($args['rewrite']['slug']) )
            $args['rewrite']['slug'] = sanitize_title_with_dashes($taxonomy);
        $wp_rewrite->add_rewrite_tag("%$taxonomy%", '([^/]+)', $args['query_var'] ? "{$args['query_var']}=" : "taxonomy=$taxonomy&term=$term");
        $wp_rewrite->add_permastruct($taxonomy, "{$args['rewrite']['slug']}/%$taxonomy%");
    }

    $args['name'] = $taxonomy;
    $args['object_type'] = $object_type;
    $wp_taxonomies[$taxonomy] = (object) $args;
}

//
// Term API
//

/**
 * get_objects_in_term() - Return object_ids of valid taxonomy and term
 *
 * The strings of $taxonomies must exist before this function will continue. On failure of finding
 * a valid taxonomy, it will return an WP_Error class, kind of like Exceptions in PHP 5, except you
 * can't catch them. Even so, you can still test for the WP_Error class and get the error message.
 *
 * The $terms aren't checked the same as $taxonomies, but still need to exist for $object_ids to
 * be returned.
 *
 * It is possible to change the order that object_ids is returned by either using PHP sort family
 * functions or using the database by using $args with either ASC or DESC array. The value should
 * be in the key named 'order'.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses $wpdb
 * @uses wp_parse_args() Creates an array from string $args.
 *
 * @param string|array $terms String of term or array of string values of terms that will be used
 * @param string|array $taxonomies String of taxonomy name or Array of string values of taxonomy names
 * @param array|string $args Change the order of the object_ids, either ASC or DESC
 * @return WP_Error|array If the taxonomy does not exist, then WP_Error will be returned. On success
 *    the array can be empty meaning that there are no $object_ids found or it will return the $object_ids found.
 */
function get_objects_in_term( $terms, $taxonomies, $args = array() ) {
    global $wpdb;

    if ( !is_array( $terms) )
        $terms = array($terms);

    if ( !is_array($taxonomies) )
        $taxonomies = array($taxonomies);

    foreach ( $taxonomies as $taxonomy ) {
        if ( ! is_taxonomy($taxonomy) )
            return new WP_Error('invalid_taxonomy', __('Invalid Taxonomy'));
    }

    $defaults = array('order' => 'ASC');
    $args = wp_parse_args( $args, $defaults );
    extract($args, EXTR_SKIP);

    $order = ( 'desc' == strtolower($order) ) ? 'DESC' : 'ASC';

    $terms = array_map('intval', $terms);

    $taxonomies = "'" . implode("', '", $taxonomies) . "'";
    $terms = "'" . implode("', '", $terms) . "'";

    $object_ids = $wpdb->get_col("SELECT tr.object_id FROM $wpdb->term_relationships AS tr INNER JOIN $wpdb->term_taxonomy AS tt ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy IN ($taxonomies) AND tt.term_id IN ($terms) ORDER BY tr.object_id $order");

    if ( ! $object_ids )
        return array();

    return $object_ids;
}

/**
 * get_term() - Get all Term data from database by Term ID.
 *
 * The usage of the get_term function is to apply filters to a term object.
 * It is possible to get a term object from the database before applying the
 * filters.
 *
 * $term ID must be part of $taxonomy, to get from the database. Failure, might be
 * able to be captured by the hooks. Failure would be the same value as $wpdb returns for the
 * get_row method.
 *
 * There are two hooks, one is specifically for each term, named 'get_term', and the second is
 * for the taxonomy name, 'term_$taxonomy'. Both hooks gets the term object, and the taxonomy
 * name as parameters. Both hooks are expected to return a Term object.
 *
 * 'get_term' hook - Takes two parameters the term Object and the taxonomy name. Must return
 * term object. Used in get_term() as a catch-all filter for every $term.
 *
 * 'get_$taxonomy' hook - Takes two parameters the term Object and the taxonomy name. Must return
 * term object. $taxonomy will be the taxonomy name, so for example, if 'category', it would be
 * 'get_category' as the filter name. Useful for custom taxonomies or plugging into default taxonomies.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses $wpdb
 * @uses sanitize_term() Cleanses the term based on $filter context before returning.
 * @see sanitize_term_field() The $context param lists the available values for get_term_by() $filter param.
 *
 * @param int|object $term If integer, will get from database. If object will apply filters and return $term.
 * @param string $taxonomy Taxonomy name that $term is part of.
 * @param string $output Constant OBJECT, ARRAY_A, or ARRAY_N
 * @param string $filter Optional, default is raw or no WordPress defined filter will applied.
 * @return mixed|null|WP_Error Term Row from database. Will return null if $term is empty. If taxonomy does not
 * exist then WP_Error will be returned.
 */
function &get_term($term, $taxonomy, $output = OBJECT, $filter = 'raw') {
    global $wpdb;

    if ( empty($term) )
        return null;

    if ( ! is_taxonomy($taxonomy) )
        return new WP_Error('invalid_taxonomy', __('Invalid Taxonomy'));

    if ( is_object($term) ) {
        wp_cache_add($term->term_id, $term, $taxonomy);
        $_term = $term;
    } else {
        $term = (int) $term;
        if ( ! $_term = wp_cache_get($term, $taxonomy) ) {
            $_term = $wpdb->get_row( $wpdb->prepare( "SELECT t.*, tt.* FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id WHERE tt.taxonomy = %s AND t.term_id = %s LIMIT 1", $taxonomy, $term) );
            wp_cache_add($term, $_term, $taxonomy);
        }
    }

    $_term = apply_filters('get_term', $_term, $taxonomy);
    $_term = apply_filters("get_$taxonomy", $_term, $taxonomy);
    $_term = sanitize_term($_term, $taxonomy, $filter);

    if ( $output == OBJECT ) {
        return $_term;
    } elseif ( $output == ARRAY_A ) {
        return get_object_vars($_term);
    } elseif ( $output == ARRAY_N ) {
        return array_values(get_object_vars($_term));
    } else {
        return $_term;
    }
}

/**
 * get_term_by() - Get all Term data from database by Term field and data.
 *
 * Warning: $value is not escaped for 'name' $field. You must do it yourself, if required.
 *
 * The default $field is 'id', therefore it is possible to also use null for field, but not
 * recommended that you do so.
 *
 * If $value does not exist, the return value will be false. If $taxonomy exists and $field
 * and $value combinations exist, the Term will be returned.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses $wpdb
 * @uses sanitize_term() Cleanses the term based on $filter context before returning.
 * @see sanitize_term_field() The $context param lists the available values for get_term_by() $filter param.
 *
 * @param string $field Either 'slug', 'name', or 'id'
 * @param string|int $value Search for this term value
 * @param string $taxonomy Taxonomy Name
 * @param string $output Constant OBJECT, ARRAY_A, or ARRAY_N
 * @param string $filter Optional, default is raw or no WordPress defined filter will applied.
 * @return mixed Term Row from database. Will return false if $taxonomy does not exist or $term was not found.
 */
function get_term_by($field, $value, $taxonomy, $output = OBJECT, $filter = 'raw') {
    global $wpdb;

    if ( ! is_taxonomy($taxonomy) )
        return false;

    if ( 'slug' == $field ) {
        $field = 't.slug';
        $value = sanitize_title($value);
        if ( empty($value) )
            return false;
    } else if ( 'name' == $field ) {
        // Assume already escaped
        $field = 't.name';
    } else {
        $field = 't.term_id';
        $value = (int) $value;
    }

    $term = $wpdb->get_row( $wpdb->prepare( "SELECT t.*, tt.* FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id WHERE tt.taxonomy = %s AND $field = %s LIMIT 1", $taxonomy, $value) );
    if ( !$term )
        return false;

    wp_cache_add($term->term_id, $term, $taxonomy);

    $term = sanitize_term($term, $taxonomy, $filter);

    if ( $output == OBJECT ) {
        return $term;
    } elseif ( $output == ARRAY_A ) {
        return get_object_vars($term);
    } elseif ( $output == ARRAY_N ) {
        return array_values(get_object_vars($term));
    } else {
        return $term;
    }
}

/**
 * get_term_children() - Merge all term children into a single array.
 *
 * This recursive function will merge all of the children of $term into
 * the same array. Only useful for taxonomies which are hierarchical.
 *
 * Will return an empty array if $term does not exist in $taxonomy.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses $wpdb
 * @uses _get_term_hierarchy()
 * @uses get_term_children() Used to get the children of both $taxonomy and the parent $term
 *
 * @param string $term Name of Term to get children
 * @param string $taxonomy Taxonomy Name
 * @return array|WP_Error List of Term Objects. WP_Error returned if $taxonomy does not exist
 */
function get_term_children( $term, $taxonomy ) {
    if ( ! is_taxonomy($taxonomy) )
        return new WP_Error('invalid_taxonomy', __('Invalid Taxonomy'));

    $terms = _get_term_hierarchy($taxonomy);

    if ( ! isset($terms[$term]) )
        return array();

    $children = $terms[$term];

    foreach ( $terms[$term] as $child ) {
        if ( isset($terms[$child]) )
            $children = array_merge($children, get_term_children($child, $taxonomy));
    }

    return $children;
}

/**
 * get_term_field() - Get sanitized Term field
 *
 * Does checks for $term, based on the $taxonomy. The function is for
 * contextual reasons and for simplicity of usage. See sanitize_term_field() for
 * more information.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses sanitize_term_field() Passes the return value in sanitize_term_field on success.
 *
 * @param string $field Term field to fetch
 * @param int $term Term ID
 * @param string $taxonomy Taxonomy Name
 * @param string $context Optional, default is display. Look at sanitize_term_field() for available options.
 * @return mixed Will return an empty string if $term is not an object or if $field is not set in $term.
 */
function get_term_field( $field, $term, $taxonomy, $context = 'display' ) {
    $term = (int) $term;
    $term = get_term( $term, $taxonomy );
    if ( is_wp_error($term) )
        return $term;

    if ( !is_object($term) )
        return '';

    if ( !isset($term->$field) )
        return '';

    return sanitize_term_field($field, $term->$field, $term->term_id, $taxonomy, $context);
}

/**
 * get_term_to_edit() - Sanitizes Term for editing
 *
 * Return value is sanitize_term() and usage is for sanitizing the term
 * for editing. Function is for contextual and simplicity.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses sanitize_term() Passes the return value on success
 *
 * @param int|object $id Term ID or Object
 * @param string $taxonomy Taxonomy Name
 * @return mixed|null|WP_Error Will return empty string if $term is not an object.
 */
function get_term_to_edit( $id, $taxonomy ) {
    $term = get_term( $id, $taxonomy );

    if ( is_wp_error($term) )
        return $term;

    if ( !is_object($term) )
        return '';

    return sanitize_term($term, $taxonomy, 'edit');
}

/**
 * get_terms() - Retrieve the terms in taxonomy or list of taxonomies.
 *
 * You can fully inject any customizations to the query before it is sent, as well as control
 * the output with a filter.
 *
 * The 'get_terms' filter will be called when the cache has the term and will pass the found
 * term along with the array of $taxonomies and array of $args. This filter is also called
 * before the array of terms is passed and will pass the array of terms, along with the $taxonomies
 * and $args.
 *
 * The 'list_terms_exclusions' filter passes the compiled exclusions along with the $args.
 *
 * The list that $args can contain, which will overwrite the defaults.
 * orderby - Default is 'name'. Can be name, count, or nothing (will use term_id).
 * order - Default is ASC. Can use DESC.
 * hide_empty - Default is true. Will not return empty $terms.
 * fields - Default is all.
 * slug - Any terms that has this value. Default is empty string.
 * hierarchical - Whether to return hierarchical taxonomy. Default is true.
 * name__like - Default is empty string.
 *
 * The argument 'pad_counts' will count all of the children along with the $terms.
 *
 * The 'get' argument allows for overwriting 'hide_empty' and 'child_of', which can be done by
 * setting the value to 'all', instead of its default empty string value.
 *
 * The 'child_of' argument will be used if you use multiple taxonomy or the first $taxonomy
 * isn't hierarchical or 'parent' isn't used. The default is 0, which will be translated to
 * a false value. If 'child_of' is set, then 'child_of' value will be tested against
 * $taxonomy to see if 'child_of' is contained within. Will return an empty array if test
 * fails.
 *
 * If 'parent' is set, then it will be used to test against the first taxonomy. Much like
 * 'child_of'. Will return an empty array if the test fails.
 *
 * @package WordPress
 * @subpackage Taxonomy
 * @since 2.3
 *
 * @uses $wpdb
 * @uses wp_parse_args() Merges the defaults with those defined by $args and allows for strings.
 *
 *
 * @param string|array Taxonomy name or list of Taxonomy names
 * @param string|array $args The values of what to search for when returning terms
 * @return array|WP_Error List of Term Objects and their children. Will return WP_Error, if any of $taxonomies do not exist.
 */
function &get_terms($taxonomies, $args = '') {
    global $wpdb;
    $empty_array = array();

    $single_taxonomy = false;
    if ( !is_array($taxonomies) ) {
        $single_taxonomy = true;
        $taxonomies = array($taxonomies);
    }

    foreach ( $taxonomies as $taxonomy ) {
        if ( ! is_taxonomy($taxonomy) )
            return new WP_Error('invalid_taxonomy', __('Invalid Taxonomy'));
    }

    $in_taxonomies = "'" . implode("', '", $taxonomies) . "'";

    $defaults = array('orderby' => 'name', 'order' => 'ASC',
        'hide_empty' => true, 'exclude' => '', 'include' => '',
        'number' => '', 'fields' => 'all', 'slug' => '', 'parent' => '',
        'hierarchical' => true, 'child_of' => 0, 'get' => '', 'name__like' => '',
        'pad_counts' => false, 'offset' => '', 'search' => '');
    $args = wp_parse_args( $args, $defaults );
    $args['number'] = absint( $args['number'] );
    $args['offset'] = absint( $args['offset'] );
    if ( !$single_taxonomy || !is_taxonomy_hierarchical($taxonomies[0]) ||
        '' != $args['parent'] ) {
        $args['child_of'] = 0;
        $args['hierarchical'] = false;
        $args['pad_counts'] = false;
    }

    if ( 'all' == $args['get'] ) {
        $args['child_of'] = 0;
        $args['hide_empty'] = 0;
        $args['hierarchical'] = false;
        $args['pad_counts'] = false;
    }
    extract($args, EXTR_SKIP);

    if ( $child_of ) {
        $hierarchy = _get_term_hierarchy($taxonomies[0]);
        if ( !isset($hierarchy[$child_of]) )
            return $empty_array;
    }

    if ( $parent ) {
        $hierarchy = _get_term_hierarchy($taxonomies[0]);
        if ( !isset($hierarchy[$parent]) )
            return $empty_array;
    }

    // $args can be whatever, only use the args defined in defaults to compute the key
    $key = md5( serialize( compact(array_keys($defaults)) ) . serialize( $taxonomies ) );

    if ( $cache = wp_cache_get( 'get_terms', 'terms' ) ) {
        if ( isset( $cache[ $key ] ) )
            return apply_filters('get_terms', $cache[$key], $taxonomies, $args);
    }

    if ( 'count' == $orderby )
        $orderby = 'tt.count';
    else if ( 'name' == $orderby )
        $orderby = 't.name';
    else if ( 'slug' == $orderby )
        $orderby = 't.slug';
    else if ( 'term_group' == $orderby )
        $orderby = 't.term_group';
    else
        $orderby = 't.term_id';

    $where = '';
    $inclusions = '';
    if ( !empty($include) ) {
        $exclude = '';
        $interms = preg_split('/[\s,]+/',$include);
        if ( count($interms) ) {
            foreach ( $interms as $interm ) {
                if (empty($inclusions))
                    $inclusions = ' AND ( t.term_id = ' . intval($interm) . ' ';
                else
                    $inclusions .= ' OR t.term_id = ' . intval($interm) . ' ';
            }
        }
    }

    if ( !empty($inclusions) )
        $inclusions .= ')';
    $where .=