diff --git a/system/Entity.php b/system/Entity.php
index 2f4e4994fac7..c489d66df0e7 100644
--- a/system/Entity.php
+++ b/system/Entity.php
@@ -64,6 +64,15 @@ class Entity
 		'casts' => []
 	];
 
+	/**
+	 * Holds original copies of all class vars so
+	 * we can determine what's actually been changed
+	 * and not accidentally write nulls where we shouldn't.
+	 *
+	 * @var array
+	 */
+	protected $_original = [];
+
 	/**
 	 * Allows filling in Entity parameters during construction.
 	 *
@@ -71,6 +80,20 @@ class Entity
 	 */
 	public function __construct(array $data = null)
 	{
+		// Collect any original values of things
+		// so we can compare later to see what's changed
+		$properties = get_object_vars($this);
+
+		foreach ($properties as $key => $value)
+		{
+			if (substr($key, 0, 1) == '_')
+			{
+				unset($properties[$key]);
+			}
+		}
+
+		$this->_original = $properties;
+
 		if (is_array($data))
 		{
 			$this->fill($data);
@@ -108,8 +131,12 @@ public function fill(array $data)
 	 * values of this entity as an array. All values are accessed
 	 * through the __get() magic method so will have any casts, etc
 	 * applied to them.
+	 *
+	 * @param bool $onlyChanged     If true, only return values that have changed since object creation
+	 *
+	 * @return array
 	 */
-	public function toArray(): array
+	public function toArray(bool $onlyChanged = false): array
 	{
 		$return = [];
 
@@ -119,7 +146,12 @@ public function toArray(): array
 
 		foreach ($properties as $key => $value)
 		{
-			if ($key == '_options') continue;
+			if (substr($key, 0, 1) == '_') continue;
+
+			if ($onlyChanged && $this->_original[$key] === null && $value === null)
+			{
+				continue;
+			}
 
 			$return[$key] = $this->__get($key);
 		}
@@ -368,7 +400,7 @@ protected function mutateDate($value)
 	 *
 	 * @return mixed
 	 */
-	
+
 	protected function castAs($value, string $type)
 	{
 		switch($type)
@@ -422,7 +454,7 @@ protected function castAs($value, string $type)
 	 * Cast as JSON
 	 *
 	 * @param mixed $value
-	 * @param bool $asArray 
+	 * @param bool $asArray
 	 *
 	 * @return mixed
 	 */
diff --git a/system/Model.php b/system/Model.php
index aa9d0aeda22a..5b413ad79ad7 100644
--- a/system/Model.php
+++ b/system/Model.php
@@ -479,45 +479,59 @@ public function save($data)
 	 * properties as an array suitable for use in creates and updates.
 	 *
 	 * @param string|object $data
-	 * @param string $dateFormat
+	 * @param string        $dateFormat
 	 *
 	 * @return array
+	 * @throws \ReflectionException
 	 */
 	public static function classToArray($data, string $dateFormat = 'datetime'): array
 	{
-		$mirror = new \ReflectionClass($data);
-		$props = $mirror->getProperties(\ReflectionProperty::IS_PUBLIC | \ReflectionProperty::IS_PROTECTED);
-
-		$properties = [];
-
-		// Loop over each property,
-		// saving the name/value in a new array we can return.
-		foreach ($props as $prop)
+		if (method_exists($data, 'toArray'))
+		{
+			$properties = $data->toArray(true);
+		}
+		else
 		{
-			// Must make protected values accessible.
-			$prop->setAccessible(true);
-			$propName = $prop->getName();
-			$properties[$propName] = $prop->getValue($data);
+			$mirror = new \ReflectionClass($data);
+			$props  = $mirror->getProperties(\ReflectionProperty::IS_PUBLIC | \ReflectionProperty::IS_PROTECTED);
+
+			$properties = [];
 
-			// Convert any Time instances to appropriate $dateFormat
-			if ($properties[$propName] instanceof Time)
+			// Loop over each property,
+			// saving the name/value in a new array we can return.
+			foreach ($props as $prop)
 			{
-				$converted = (string)$properties[$propName];
+				// Must make protected values accessible.
+				$prop->setAccessible(true);
+				$propName              = $prop->getName();
+				$properties[$propName] = $prop->getValue($data);
+			}
+		}
 
-				switch($dateFormat)
+		// Convert any Time instances to appropriate $dateFormat
+		if (count($properties))
+		{
+			foreach ($properties as $key => $value)
+			{
+				if ($value instanceof Time)
 				{
-					case 'datetime':
-						$converted = $properties[$propName]->format('Y-m-d H:i:s');
-						break;
-					case 'date':
-						$converted = $properties[$propName]->format('Y-m-d');
-						break;
-					case 'int':
-						$converted = $properties[$propName]->getTimestamp();
-						break;
-				}
+					switch ($dateFormat)
+					{
+						case 'datetime':
+							$converted = $value->format('Y-m-d H:i:s');
+							break;
+						case 'date':
+							$converted = $value->format('Y-m-d');
+							break;
+						case 'int':
+							$converted = $value->getTimestamp();
+							break;
+						default:
+							$converted = (string)$value;
+					}
 
-				$properties[$prop->getName()] = $converted;
+					$properties[$key] = $converted;
+				}
 			}
 		}
 
@@ -1077,11 +1091,14 @@ protected function doProtectFields($data)
 			throw DataException::forInvalidAllowedFields(get_class($this));
 		}
 
-		foreach ($data as $key => $val)
+		if (is_array($data) && count($data))
 		{
-			if ( ! in_array($key, $this->allowedFields))
+			foreach ($data as $key => $val)
 			{
-				unset($data[$key]);
+				if (! in_array($key, $this->allowedFields))
+				{
+					unset($data[$key]);
+				}
 			}
 		}
 
diff --git a/tests/_support/Models/SimpleEntity.php b/tests/_support/Models/SimpleEntity.php
index 2664fb7294f1..31d29a4b99c8 100644
--- a/tests/_support/Models/SimpleEntity.php
+++ b/tests/_support/Models/SimpleEntity.php
@@ -17,4 +17,9 @@ class SimpleEntity extends Entity
     protected $description;
     protected $created_at;
 
+	protected $_options = [
+		'datamap' => [],
+		'dates' => ['created_at', 'updated_at', 'deleted_at'],
+		'casts' => []
+	];
 }
diff --git a/tests/system/Database/Live/ModelTest.php b/tests/system/Database/Live/ModelTest.php
index baa8387e8484..221911d7e777 100644
--- a/tests/system/Database/Live/ModelTest.php
+++ b/tests/system/Database/Live/ModelTest.php
@@ -712,4 +712,28 @@ public function testUpdateBatchValidationFail()
 	}
 
 	//--------------------------------------------------------------------
+
+	public function testSelectAndEntitiesSaveOnlyChangedValues()
+	{
+		$this->hasInDatabase('job', [
+			'name' => 'Rocket Scientist',
+			'description' => 'Plays guitar for Queen',
+			'created_at' => date('Y-m-d H:i:s')
+		]);
+
+		$model = new EntityModel();
+
+		$job = $model->select('id, name')->where('name', 'Rocket Scientist')->first();
+
+		$this->assertNull($job->description);
+		$this->assertEquals('Rocket Scientist', $job->name);
+
+		$model->save($job);
+
+		$this->seeInDatabase('job', [
+			'id' => $job->id,
+			'name' => 'Rocket Scientist',
+			'description' => 'Plays guitar for Queen',
+		]);
+	}
 }
diff --git a/tests/system/View/ParserTest.php b/tests/system/View/ParserTest.php
index 3ed3958aee10..24bba776d7ee 100644
--- a/tests/system/View/ParserTest.php
+++ b/tests/system/View/ParserTest.php
@@ -213,7 +213,7 @@ public function testParseLoopEntityProperties()
 		$power = new class extends \CodeIgniter\Entity {
 			public $foo = 'bar';
 			protected $bar = 'baz';
-			public function toArray(): array
+			public function toArray(bool $onlyChanged = false): array
 			{
 				return [
 					'foo' => $this->foo,