[7.x] Add setNullOnDelete in ForeignKeyDefinition (#33551)

* [7.x] Add setNullOnDelete in ForeignKeyDefinition

Signed-off-by: Lloric Mayuga Garcia <[email protected]>

* Update ForeignKeyDefinition.php

Co-authored-by: Taylor Otwell <[email protected]>

Author: lloricode

src/Illuminate/Database/Schema/ForeignKeyDefinition.php

@@ -33,4 +33,14 @@ public function cascadeOnDelete()
     {
         return $this->onDelete('cascade');
     }
+
+    /**
+     * Indicate that deletes should set the foreign key value to null.
+     *
+     * @return $this
+     */
+    public function nullOnDelete()
+    {
+        return $this->onDelete('set null');
+    }
 }