Create new content using Sonata Admin when mapped entity is an abstract class

Question

I am trying to create new content using Sonata Admin, however due the entity is an abstract class I am getting on screen a new panel with title Select object type and the content has a blue box that says No object types available.

I don't know what kind of settings I need to set-up in order to be able to select and create one of the entities that are extending my abstract class.

Any help will be more than welcomed!

AppBundle\Entity\AbstractAlert

 /**
  * @ORM\InheritanceType("SINGLE_TABLE")
  * @ORM\DiscriminatorColumn(
  *     name="dtype",
  *     type="string"
  * )
  * @ORM\DiscriminatorMap({
  *     "email" = "AppBundle\Entity\EmailAlert",
  *     "sms" = "AppBundle\Entity\SmsAlert"
  * })
  */
 abstract class AbstractAlert
 {
 }

AppBundle\Entity\EmailAlert

 class EmailAlert extends AbstractAlert
 {
 }

AppBundle\Entity\SmsAlert

 class SmsAlert extends AbstractAlert
 {
 }

SonataAdminBundle\Admin\AlertAdmin

 class MassiveAlertAdmin extends AbstractAdmin
 {
     protected function configureFormFields(FormMapper $form)
     {
         $form
             ->with('panel name')
             ->add('fieldName')
             ->end();
     }
 }

This is how it looks my Sonata Admin => Create page

If any of you can give me a clue please, I will appreciate it.

Thanks in advance for your help,

Answer 1

Ok, i was wrong and finally found a solution for you ... you have only to choose the abstract entity as you already got and set subclasses via DI as shown here in 16.3 https://sonata-project.org/bundles/admin/2-1/doc/reference/advance.html ... that works like a charm and you'll get your choices in the add button! If not, i could imagine, that every concrete entity class also must have a own admin services, my classes already does. And for me: learning never stops ... Sorry for my wrong answer in the previous post ... having this knowledge helps me also now, improving my code. Thanks for that.

Answer 2

From 11/2018, i have the same problem but i use yaml to the config of the services.

The class 'Operation' is the abstract one.

Here is a example with yaml

app.admin.operation:
  class: App\Admin\OperationAdmin
  arguments: [~, App\Entity\Operation, ~]
  tags:
    - { name: sonata.admin, manager_type: orm, group: "app.admin.group.operation", label: Operation }
  calls:
    - [ setSubClasses, [{ TeamOperation: App\Entity\TeamOperation, Staff: App\Entity\StaffOperation, PlayersOperation: App\Entity\PlayersOperation} ]]

Whit this type of configuration you can select the type of 'Operation' between that 3 entities.