Doctrine：双向OneToOne关系，两个实体都被删除

Hey guys so I have 2 entities with a bidirectional OneToOne relationship:

Sale.php

/**
 * @var TransportInvoice
 *
 * @ORM\OneToOne(targetEntity="WKDA\Common\Entity\Car\TransportInvoice\TransportInvoice",  mappedBy="sale")
 * @ORM\JoinColumn(name="transport_invoice", referencedColumnName="id", nullable=true, onDelete="SET NULL")
 */
protected $transportInvoice;

TransportInvoice.php

/**
 * @var Sale
 * @ORM\OneToOne(targetEntity="WKDA\Common\Entity\Car\Sale", inversedBy="transportInvoice", cascade={"persist"}, orphanRemoval=true)
 * @ORM\JoinColumn(name="sale", referencedColumnName="id", nullable=false)
 */
protected $sale;

In my controller, to delete a transport invoice from the sale, the following is done:

$transportInvoice = $car->getSale()->getTransportInvoice();
            $em = $this->getEntityManager();

            $em->remove($transportInvoice);
            $em->flush();

This deletes the TransportInvoice, but it deletes the Sale object as well. I don't want the Sale object to be deleted, I just want the TransportInvoice parameter within sale to be null. What am I not understanding?

If this is not clear let me know, thanks for your help!

I think that the problem is the relation design. In your example Sale is the main entity, so the transport_invoice reference is not needed. The "sale" reference in TransportInvoice.php is all that doctrine need, so edit Sale as follow an try again.

/**
 * @var TransportInvoice
 *
 * @ORM\OneToOne(targetEntity="WKDA\Common\Entity\Car\TransportInvoice\TransportInvoice",  mappedBy="sale")
 */
protected $transportInvoice;

I hope it help you.