Fixes #10422, #9574: New proposal fix for ColumnSchemaBuilder not null column

* Added ability to explicitly set column nullability #10422

* Removed isNull property.

* add since tag.

framework/CHANGELOG.md

@@ -5,6 +5,7 @@ Yii Framework 2 Change Log
 2.0.9 under development
 -----------------------
 
+- Enh #10422: Added `null` method on `yii\db\ColumnSchemaBuilder` to explicitly set column nullability (nevermnd)
 - Enh #8795: Refactored `yii\web\User::loginByCookie()` in order to make it easier to override (maine-mike, silverfire)
 - Enh #9948: `yii\rbac\PhpManager` now invalidates script file cache performed by 'OPCache' or 'APC' on file saving (klimov-paul)
 - Enh #11195: Added ability to append custom string to schema builder column definition (df2, samdark)

framework/db/ColumnSchemaBuilder.php

@@ -40,9 +40,10 @@ class ColumnSchemaBuilder extends Object
      */
     protected $length;
     /**
-     * @var boolean whether the column is not nullable. If this is `true`, a `NOT NULL` constraint will be added.
+     * @var boolean|null whether the column is or not nullable. If this is `true`, a `NOT NULL` constraint will be added.
+     * If this is `false`, a `NULL` constraint will be added.
      */
-    protected $isNotNull = false;
+    protected $isNotNull = null;
     /**
      * @var boolean whether the column values should be unique. If this is `true`, a `UNIQUE` constraint will be added.
      */
@@ -76,7 +77,6 @@ class ColumnSchemaBuilder extends Object
      */
     protected $isFirst;
 
-
     /**
      * @var array mapping of abstract column types (keys) to type categories (values).
      * @since 2.0.8
@@ -141,6 +141,17 @@ class ColumnSchemaBuilder extends Object
         return $this;
     }
 
+    /**
+     * Adds a `NULL` constraint to the column
+     * @return $this
+     * @since 2.0.9
+     */
+    public function null()
+    {
+        $this->isNotNull = false;
+        return $this;
+    }
+
     /**
      * Adds a `UNIQUE` constraint to the column.
      * @return $this
@@ -286,11 +297,18 @@ class ColumnSchemaBuilder extends Object
 
     /**
      * Builds the not null constraint for the column.
-     * @return string returns 'NOT NULL' if [[isNotNull]] is true, otherwise it returns an empty string.
+     * @return string returns 'NOT NULL' if [[isNotNull]] is true, 
+     * 'NULL' if [[isNotNull]] is false or an empty string otherwise.
      */
     protected function buildNotNullString()
     {
-        return $this->isNotNull ? ' NOT NULL' : '';
+        if ($this->isNotNull === true) {
+            return ' NOT NULL';
+        } elseif ($this->isNotNull === false) {
+            return ' NULL';
+        } else {
+            return '';
+        }
     }
 
     /**

tests/framework/db/ColumnSchemaBuilderTest.php

@@ -9,7 +9,6 @@ namespace yiiunit\framework\db;
 
 
 use yii\db\ColumnSchemaBuilder;
-use yii\db\Exception;
 use yii\db\Expression;
 use yii\db\Schema;
 use yiiunit\TestCase;
@@ -35,8 +34,8 @@ class ColumnSchemaBuilderTest extends TestCase
     public function typesProvider()
     {
         return [
-            ['integer', Schema::TYPE_INTEGER, null, [
-                ['unsigned'],
+            ['integer NULL', Schema::TYPE_INTEGER, null, [
+                ['unsigned'], ['null'],
             ]],
             ['integer(10)', Schema::TYPE_INTEGER, 10, [
                 ['unsigned'],