I get the "Column 'member_received' cannot be null"  error when I use the react() method. the query has the reaction parameter and the $item is an object which not null.
 

$item->react(\IPS\Content\Reaction::load( \IPS\Request::i()->reaction ));

 

Does the item have an author? Is it probably some guest content or was the author deleted?

Thank You , I got it