function awpcp_extra_fields_render_field($field, $value, $category, $context, $errors = array())
 {
     $label = stripslashes_deep($field->field_label);
     $name = "awpcp-{$field->field_name}";
     $type = $field->field_input_type;
     $id = $name;
     $classes = array_filter(array('awpcp-form-spacer', 'awpcp-extra-field', "awpcp-extra-field-{$field->field_name}"));
     foreach ($field->field_category as $category_id) {
         $classes[] = "awpcp-extra-field-category-{$category_id}";
     }
     $all_categories = awpcp_get_categories_ids();
     // always show field if no category is selected or all categories are selected
     if (empty($field->field_category) || count(array_diff($all_categories, $field->field_category)) == 0) {
         $classes[] = 'awpcp-extra-field-always-visible';
         // hide fields that belong to a different category
     } else {
         if (!empty($category) && !in_array($category, $field->field_category)) {
             $classes[] = 'awpcp-extra-field-hidden';
         }
     }
     $validators = array();
     switch ($field->field_validation) {
         case 'email':
             $validators[] = 'email';
             break;
         case 'url':
             $validators[] = 'url';
             break;
         case 'currency':
             $validators[] = 'money';
             break;
         case 'missing':
             $validators[] = 'required';
             break;
         case 'numericdeci':
             $validators[] = 'number';
             break;
         case 'numericnodeci':
             $validators[] = 'integer';
             break;
     }
     if ($context != 'search' && $field->required && $field->field_validation != 'missing') {
         $validators[] = 'required';
     }
     $validator = join(' ', $validators);
     /* Range Search support */
     $has_numeric_data_type = in_array($field->field_mysql_data_type, array('INT', 'FLOAT'));
     $has_numeric_validator = in_array($field->field_validation, array('numericdeci', 'numericnodeci'));
     $is_single_valued = in_array($type, array('Input Box', 'Select', 'Radio Button'));
     // TODO: pass min and max values
     if ($context == 'search' && $is_single_valued && ($has_numeric_validator || $has_numeric_data_type)) {
         $id = "awpcp-extra-field-{$name}-min";
         $body = '<span class="awpcp-range-search">';
         $body .= '<label for="%1$s-min">' . __('Min', 'awpcp-extra-fields') . '</label>';
         $body .= '<input id="%1$s-min" class="inputbox %2$s" type="text" name="%3$s-min" value="%4$s">';
         $body .= '<label for="%1$s-max">' . __('Max', 'awpcp-extra-fields') . '</label>';
         $body .= '<input id="%1$s-max" class="inputbox %2$s" type="text" name="%3$s-max" value="%5$s">';
         $body .= '</span>';
         if (!is_array($value)) {
             $value = stripslashes_deep(array('min' => $value, 'max' => $value));
         }
         $body = sprintf($body, "awpcp-extra-field-{$name}", $validator, $name, $value['min'], $value['max']);
         /* Normal Input */
     } else {
         if ($type == 'Input Box') {
             $body = '<input id="%s" class="inputbox %s" type="text" name="%s" value="%s">';
             $body = sprintf($body, $name, $validator, $name, stripslashes($value));
         } else {
             if ($type == 'Select') {
                 $options = array(sprintf('<option value="">%s</option>', __('Select One', 'awpcp-extra-fields')));
                 foreach ($field->field_options as $option) {
                     $option = trim($option);
                     $_html = '<option %s value="%s">%s</option>';
                     $_html = sprintf($_html, $value == $option ? 'selected' : '', awpcp_esc_attr($option), stripslashes($option));
                     $options[] = $_html;
                 }
                 $body = sprintf('<select id="%s" class="%s" name="%s">%s</select>', $name, $validator, $name, join('', $options));
             } else {
                 if ($type == 'Textarea Input') {
                     $body = '<textarea id="%s" class="awpcp-textarea textareainput %s" name="%s" rows="10" cols="50">%s</textarea>';
                     $body = sprintf($body, $name, $validator, $name, awpcp_esc_textarea($value));
                 } else {
                     if ($type == 'Radio Button') {
                         $options = array();
                         foreach ($field->field_options as $option) {
                             $_html = '<label class="secondary-label"><input class="%s" type="radio" %s name="%s" value="%s">%s</label><br>';
                             $_html = sprintf($_html, $validator, $value == $option ? 'checked' : '', $name, awpcp_esc_attr($option), stripslashes($option));
                             $options[] = $_html;
                         }
                         $body = join('', $options);
                     } else {
                         if ($type == 'Select Multiple') {
                             $value = is_array($value) ? $value : explode(',', $value);
                             $options = array();
                             foreach ($field->field_options as $option) {
                                 $option = trim($option);
                                 $_html = '<option %s value="%s">%s</option>';
                                 $options[] = sprintf($_html, in_array($option, $value) ? 'selected' : '', awpcp_esc_attr($option), stripslashes($option));
                             }
                             $body = '<select id="%s" class="%s" name="%s[]" multiple style="width:25%%;height:100px">%s</select>';
                             $body = sprintf($body, $name, $validator, $name, join('', $options));
                         } else {
                             if ($type == 'Checkbox') {
                                 $value = is_array($value) ? $value : explode(',', $value);
                                 $options = array();
                                 foreach ($field->field_options as $option) {
                                     $_html = '<label class="secondary-label"><input class="%s" type="checkbox" %s name="%s[]" value="%s">%s</label><br>';
                                     $options[] = sprintf($_html, $validator, in_array($option, $value) ? 'checked' : '', $name, awpcp_esc_attr($option), stripslashes($option));
                                 }
                                 $body = join('', $options);
                             }
                         }
                     }
                 }
             }
         }
     }
     $error = awpcp_form_error($field->field_name, $errors);
     $html = '<p class="%s" data-category="%s"><label for="%s">%s</label>%s %s</p>';
     return sprintf($html, join(' ', $classes), join(',', $field->field_category), $id, $label, $body, $error);
 }
 /**
  * TODO: make dependency on the list of categories explicit
  */
 private function should_be_always_visible()
 {
     if (empty($this->extra_field->field_category)) {
         return true;
     }
     if (count(array_diff(awpcp_get_categories_ids(), $this->extra_field->field_category)) == 0) {
         return true;
     }
     return false;
 }