diff --git a/public/customfield/classes/data.php b/public/customfield/classes/data.php
index 99d5a205fac..da1fabf9e5a 100644
--- a/public/customfield/classes/data.php
+++ b/public/customfield/classes/data.php
@@ -14,24 +14,14 @@
 // You should have received a copy of the GNU General Public License
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
-/**
- * Data persistent class
- *
- * @package   core_customfield
- * @copyright 2018 Toni Barbera <toni@moodle.com>
- * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
- */
-
 namespace core_customfield;
 
 use core\persistent;
 
-defined('MOODLE_INTERNAL') || die;
-
 /**
- * Class data
+ * Data persistent class
  *
- * @package core_customfield
+ * @package   core_customfield
  * @copyright 2018 Toni Barbera <toni@moodle.com>
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
@@ -121,4 +111,35 @@ class data extends persistent {
         );
     }
 
+    /**
+     * For integer data field, persistent won't allow empty string, swap for null
+     *
+     * @param string|null $value
+     * @return self
+     */
+    protected function set_intvalue(?string $value): self {
+        $value = (string) $value === '' ? null : (int) $value;
+        return $this->raw_set('intvalue', $value);
+    }
+
+    /**
+     * For decimal data field, persistent won't allow empty string, swap for null
+     *
+     * @param string|null $value
+     * @return self
+     */
+    protected function set_decvalue(?string $value): self {
+        $value = (string) $value === '' ? null : (float) $value;
+        return $this->raw_set('decvalue', $value);
+    }
+
+    /**
+     * Ensure value field observes non-nullability
+     *
+     * @param string|null $value
+     * @return self
+     */
+    protected function set_value(?string $value): self {
+        return $this->raw_set('value', (string) $value);
+    }
 }
diff --git a/public/customfield/classes/data_controller.php b/public/customfield/classes/data_controller.php
index ead81c30ff8..77d4b01015d 100644
--- a/public/customfield/classes/data_controller.php
+++ b/public/customfield/classes/data_controller.php
@@ -14,21 +14,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
-/**
- * Customfield component data controller abstract class
- *
- * @package   core_customfield
- * @copyright 2018 Toni Barbera <toni@moodle.com>
- * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
- */
-
 namespace core_customfield;
 
 use backup_nested_element;
 use core_customfield\output\field_data;
 
-defined('MOODLE_INTERNAL') || die;
-
 /**
  * Base class for custom fields data controllers
  *
@@ -38,7 +28,7 @@ defined('MOODLE_INTERNAL') || die;
  * Custom field plugins must define a class
  * \{pluginname}\data_controller extends \core_customfield\data_controller
  *
- * @package core_customfield
+ * @package   core_customfield
  * @copyright 2018 Toni Barbera <toni@moodle.com>
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
@@ -212,15 +202,11 @@ abstract class data_controller {
         if (!property_exists($datanew, $elementname)) {
             return;
         }
-        $datafieldvalue = $value = $datanew->{$elementname};
 
-        // For numeric datafields, persistent won't allow empty string, swap for null.
         $datafield = $this->datafield();
-        if ($datafield === 'intvalue' || $datafield === 'decvalue') {
-            $datafieldvalue = $datafieldvalue === '' ? null : $datafieldvalue;
-        }
+        $value = $datanew->{$elementname};
 
-        $this->data->set($datafield, $datafieldvalue);
+        $this->data->set($datafield, $value);
         $this->data->set('value', $value);
 
         // Set component, area and itemid from the handler.
diff --git a/public/lib/classes/persistent.php b/public/lib/classes/persistent.php
index 8308cd7988a..5ebe0076055 100644
--- a/public/lib/classes/persistent.php
+++ b/public/lib/classes/persistent.php
@@ -95,7 +95,7 @@ abstract class persistent {
      * Data setter.
      *
      * This is the main setter for all the properties. Developers can implement their own setters (set_propertyname)
-     * and they will be called by this function. Custom setters should call internal_set() to finally set the value.
+     * and they will be called by this function. Custom setters should call {@see raw_set} to finally set the value.
      * Internally this is not used {@link self::to_record()} or
      * {@link self::from_record()} because the data is not expected to be validated or changed when reading/writing
      * raw records from the DB.