Fixed null saving for JSON and Array cols in AR

Fixes #15863

Author: SilverFire

framework/CHANGELOG.md

@@ -16,6 +16,7 @@ Yii Framework 2 Change Log
 - Bug #15839: Fixed `yii\db\mysql\JsonExpressionBuilder` to cast JSON explicitly (silverfire)
 - Bug #15840: Fixed regression on load fixture data file (leandrogehlen)
 - Bug #15858: Fixed `Undefined offset` error calling `yii\helpers\Html::errorSummary()` with the same error messages for different model attributes (FabrizioCaldarelli, silverfire)
+- Bug #15863: Fixed saving of `null` attribute value for JSON and Array columns in MySQL and PostgreSQL (silverfire)
 - Bug: Fixed encoding of empty `yii\db\ArrayExpression` for PostgreSQL (silverfire)
 - Bug: Fixed table schema retrieving for PostgreSQL when the table name was wrapped in quotes (silverfire)
 

framework/db/JsonExpression.php

@@ -83,7 +83,7 @@ public function getType()
      * @link http://php.net/manual/en/jsonserializable.jsonserialize.php
      * @return mixed data which can be serialized by <b>json_encode</b>,
      * which is a value of any type other than a resource.
-     * @since 2.0.14.1
+     * @since 2.0.14.2
      * @throws InvalidConfigException when JsonExpression contains QueryInterface object
      */
     public function jsonSerialize()

framework/db/mysql/ColumnSchema.php

@@ -34,6 +34,10 @@ class ColumnSchema extends \yii\db\ColumnSchema
      */
     public function dbTypecast($value)
     {
+        if ($value === null) {
+            return $value;
+        }
+
         if ($value instanceof ExpressionInterface) {
             return $value;
         }

framework/db/pgsql/ColumnSchema.php

@@ -56,6 +56,10 @@ class ColumnSchema extends \yii\db\ColumnSchema
      */
     public function dbTypecast($value)
     {
+        if ($value === null) {
+            return $value;
+        }
+
         if ($value instanceof ExpressionInterface) {
             return $value;
         }