[9.x] Add ability to discard Eloquent Model changes (#43772)

* [9.x] Add ability to discard Eloquent Model changes.

Signed-off-by: Mior Muhammad Zaki <[email protected]>

* one line

Signed-off-by: Mior Muhammad Zaki <[email protected]>
Co-authored-by: Taylor Otwell <[email protected]>

Author: crynobone

src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php

@@ -1902,6 +1902,18 @@ public function isClean($attributes = null)
         return ! $this->isDirty(...func_get_args());
     }
 
+    /**
+     * Discard attribute changes and reset the attributes to their original state.
+     *
+     * @return $this
+     */
+    public function discardChanges()
+    {
+        [$this->attributes, $this->changes] = [$this->original, []];
+
+        return $this;
+    }
+
     /**
      * Determine if the model or any of the given attribute(s) were changed when the model was last saved.
      *

tests/Database/DatabaseEloquentModelTest.php

@@ -2423,6 +2423,23 @@ public function testUnsavedModel()
 
         $this->assertNull($user->name);
     }
+
+    public function testDiscardChanges()
+    {
+        $user = new EloquentModelStub([
+            'name' => 'Taylor Otwell',
+        ]);
+
+        $this->assertNotEmpty($user->isDirty());
+        $this->assertNull($user->getOriginal('name'));
+        $this->assertSame('Taylor Otwell', $user->getAttribute('name'));
+
+        $user->discardChanges();
+
+        $this->assertEmpty($user->isDirty());
+        $this->assertNull($user->getOriginal('name'));
+        $this->assertNull($user->getAttribute('name'));
+    }
 }
 
 class EloquentTestObserverStub

tests/Integration/Database/EloquentModelTest.php

@@ -64,6 +64,36 @@ public function testAttributeChanges()
         $this->assertTrue($user->wasChanged());
         $this->assertTrue($user->wasChanged('name'));
     }
+
+    public function testDiscardChanges()
+    {
+        $user = TestModel2::create([
+            'name' => $originalName = Str::random(), 'title' => Str::random(),
+        ]);
+
+        $this->assertEmpty($user->getDirty());
+        $this->assertEmpty($user->getChanges());
+        $this->assertFalse($user->isDirty());
+        $this->assertFalse($user->wasChanged());
+
+        $user->name = $overideName = Str::random();
+
+        $this->assertEquals(['name' => $overideName], $user->getDirty());
+        $this->assertEmpty($user->getChanges());
+        $this->assertTrue($user->isDirty());
+        $this->assertFalse($user->wasChanged());
+        $this->assertSame($originalName, $user->getOriginal('name'));
+        $this->assertSame($overideName, $user->getAttribute('name'));
+
+        $user->discardChanges();
+
+        $this->assertEmpty($user->getDirty());
+        $this->assertSame($originalName, $user->getOriginal('name'));
+        $this->assertSame($originalName, $user->getAttribute('name'));
+
+        $user->save();
+        $this->assertFalse($user->wasChanged());
+    }
 }
 
 class TestModel1 extends Model