class views_handler_relationship

class views_handler_relationship extends views_handler {
    
    /**
     * Init handler to let relationships live on tables other than
     * the table they operate on.
     */
    function init(&$view, $options) {
        parent::init($view, $options);
        if (isset($this->definition['relationship table'])) {
            $this->table = $this->definition['relationship table'];
        }
        if (isset($this->definition['relationship field'])) {
            // Set both real_field and field so custom handler
            // can rely on the old field value.
            $this->real_field = $this->field = $this->definition['relationship field'];
        }
    }
    
    /**
     * Get this field's label.
     */
    function label() {
        if (!isset($this->options['label'])) {
            return $this->ui_name();
        }
        return $this->options['label'];
    }
    function option_definition() {
        $options = parent::option_definition();
        // Relationships definitions should define a default label, but if they aren't get another default value.
        if (!empty($this->definition['label'])) {
            $label = $this->definition['label'];
        }
        else {
            $label = !empty($this->definition['field']) ? $this->definition['field'] : $this->definition['base field'];
        }
        $options['label'] = array(
            'default' => $label,
            'translatable' => TRUE,
        );
        $options['required'] = array(
            'default' => FALSE,
        );
        return $options;
    }
    
    /**
     * Default options form that provides the label widget that all fields
     * should have.
     */
    function options_form(&$form, &$form_state) {
        parent::options_form($form, $form_state);
        $form['label'] = array(
            '#type' => 'textfield',
            '#title' => t('Label'),
            '#default_value' => isset($this->options['label']) ? $this->options['label'] : '',
            '#description' => t('The label for this relationship that will be displayed only administratively.'),
            '#required' => TRUE,
        );
        $form['required'] = array(
            '#type' => 'checkbox',
            '#title' => t('Require this relationship'),
            '#description' => t('If required, items that do not contain this relationship will not appear.'),
            '#default_value' => !empty($this->options['required']),
        );
    }
    
    /**
     * Called to implement a relationship in a query.
     */
    function query() {
        // Figure out what base table this relationship brings to the party.
        $table_data = views_fetch_data($this->definition['base']);
        $base_field = empty($this->definition['base field']) ? $table_data['table']['base']['field'] : $this->definition['base field'];
        $this->ensure_my_table();
        $def = $this->definition;
        $def['table'] = $this->definition['base'];
        $def['field'] = $base_field;
        $def['left_table'] = $this->table_alias;
        $def['left_field'] = $this->real_field;
        if (!empty($this->options['required'])) {
            $def['type'] = 'INNER';
        }
        if (!empty($this->definition['extra'])) {
            $def['extra'] = $this->definition['extra'];
        }
        if (!empty($def['join_handler']) && class_exists($def['join_handler'], FALSE)) {
            $join = new $def['join_handler']();
        }
        else {
            $join = new views_join();
        }
        $join->definition = $def;
        $join->options = $this->options;
        $join->construct();
        $join->adjusted = TRUE;
        // use a short alias for this:
        $alias = $def['table'] . '_' . $this->table;
        $this->alias = $this->query
            ->add_relationship($alias, $join, $this->definition['base'], $this->relationship);
    }
    
    /**
     * You can't groupby a relationship.
     */
    function use_group_by() {
        return FALSE;
    }

}