php - Sonata admin "sonata_type_collection" tries to remove entity -

i have 2 entities , 2 admin classes(stripepage , stripe) them. form looks good, has fields , button add new subforms. when "add new" button clicked, new subform form admin class rendered, if click second time on button or try save entity error appears:

catchable fatal error: argument 1 passed fred\corebundle\entity\stripepage::removestripe() must instance of fred\corebundle\entity\stripe, null given in c:\users\lubimov\openserver\domains\tappic.dev\src\fred\corebundle\entity\stripepage.php

so symfony tries remove entity instead of adding it.

stripepageadmin class:

class stripepageadmin extends admin {     protected function configurelistfields(listmapper $listmapper)     {         $listmapper             ->addidentifier('id', null, array('label' => 'id'))             ->add('name', null, array('label' => 'page name'));     }      protected function configureformfields(formmapper $formmapper)     {         $formmapper             ->add('name', 'text', array('label' => 'page name'))             ->add('stripes', 'sonata_type_collection',                 array('label' => 'stripes', 'required' => false, 'by_reference' => false),                 array('edit' => 'inline', 'inline' => 'table', 'sortable' => 'pos')             )             ->end();     } } 

stripeadmin class:

class stripeadmin extends admin {     protected function configurelistfields(listmapper $listmapper)     {         $listmapper             ->addidentifier('id')             ->add('picture', null, array('sortable' => true))             ->add('text', null, array('sortable' => true))             ->add('deep_link', null, array('sortable' => true));     }      protected function configureformfields(formmapper $formmapper)     {         $formmapper             ->add('file', 'file', array('label' => 'picture'))             ->add('text', null, array('label' => 'text'))             ->add('deep_link', 'choice', array(                 'choices'  => array('test1' => 'test1', 'test' => 'test2'),                 'label' => 'deep link',             ))             ->end();     } } 

what problem? stripe form in admin class must configured other way?

well, solution use set 'by_reference' => true in 'sonata_type_collection' settings.

protected function configureformfields(formmapper $formmapper) {     $formmapper         ->add('name', 'text', array('label' => 'page name'))         ->add('stripes', 'sonata_type_collection',             array('label' => 'stripes', 'required' => false, 'by_reference' => true),             array('edit' => 'inline', 'inline' => 'table', 'sortable' => 'pos')         )         ->end(); } 

after need declare setstripes() method in entity.

public function setstripes(\doctrine\common\collections\arraycollection $stripes) {     $this->stripes = $stripes; } 

if finds how solve using addstripe() type of methods, please share here.