add virtual columns array

src/VirtualColumn.php

@@ -45,7 +45,10 @@ trait VirtualColumn
         }
 
         foreach ($model->getAttributes() as $key => $value) {
-            if (! in_array($key, static::getCustomColumns())) {
+
+            if ((static::getVirtualColumns() && in_array($key, static::getVirtualColumns(), true))
+                || ! in_array($key, static::getCustomColumns())
+            ) {
                 $current = $model->getAttribute(static::getDataColumn()) ?? [];
 
                 $model->setAttribute(static::getDataColumn(), array_merge($current, [
@@ -133,6 +136,13 @@ trait VirtualColumn
         return 'data';
     }
 
+    public static function getVirtualColumns(): array
+    {
+        return [
+            //
+        ];
+    }
+
     public static function getCustomColumns(): array
     {
         return [

tests/VirtualColumnTest.php

@@ -57,6 +57,49 @@ class VirtualColumnTest extends TestCase
         $this->assertSame(null, $model->data);
     }
 
+    /** @test */
+    public function keys_defined_in_the_virtual_columns_function_go_into_data_json_column()
+    {
+        $model = VirtualModel::create([
+            'id' => 1,
+            'foo' => 'bar',
+        ]);
+
+        // Test that model works correctly
+        $this->assertSame(1, $model->id);
+        $this->assertSame('bar', $model->foo);
+        $this->assertSame(null, $model->data);
+
+        // Low level test to assert database structure
+        $this->assertSame(['foo' => 'bar'], json_decode(DB::table('virtual_models')->where('id', $model->id)->first()->data, true));
+        $this->assertSame(null, DB::table('virtual_models')->where('id', $model->id)->first()->foo ?? null);
+
+        // Model has the correct structure when retrieved
+        $model = VirtualModel::first();
+        $this->assertSame('bar', $model->foo);
+        $this->assertSame('bar', $model->getOriginal('foo'));
+        $this->assertSame(null, $model->data);
+
+        // Model can be updated
+        $model->update([
+            'foo' => 'baz',
+            'abc' => 'xyz',
+        ]);
+
+        $this->assertSame('baz', $model->foo);
+        $this->assertSame('baz', $model->getOriginal('foo'));
+        $this->assertSame('xyz', $model->abc);
+        $this->assertSame('xyz', $model->getOriginal('abc'));
+        $this->assertSame(null, $model->data);
+
+        // Model can be retrieved after update & is structure correctly
+        $model = VirtualModel::first();
+
+        $this->assertSame('baz', $model->foo);
+        $this->assertSame('xyz', $model->abc);
+        $this->assertSame(null, $model->data);
+    }
+
     /** @test */
     public function model_is_always_decoded_when_accessed_by_user_event()
     {
@@ -125,6 +168,24 @@ class MyModel extends Model
     }
 }
 
+class VirtualModel extends Model
+{
+    use VirtualColumn;
+
+    protected $guarded = [];
+    public $timestamps = false;
+
+    public static function getVirtualColumns(): array
+    {
+        return [
+            'foo',
+            'abc',
+            'baz',
+            'xyz',
+        ];
+    }
+}
+
 class FooModel extends Model
 {
     use VirtualColumn;

tests/etc/migrations/2022_10_24_000001_create_virtual_models_table.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class CreateVirtualModelsTable extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::create('virtual_models', function (Blueprint $table) {
+            $table->increments('id');
+
+            $table->json('data');
+        });
+    }
+
+    public function down()
+    {
+        Schema::dropIfExists('foo_models');
+    }
+}