I have this two tables (see pics below) mapped as follow:

class Brand
{
    ...
    /**
     * @var Company
     *
     * @ORM\ManyToOne(targetEntity="Company")
     * @ORM\JoinColumn(name="companies_id", referencedColumnName="id")
     */
    protected $company;
}
class Company
{
    ...  
}
I need to add support for add a new Brand from Company but I have not idea in how to achieve this. This are handled through SonataAdminBundle but I think I need to add something else to entities in order to create brands from company but I am not sure what this would be, can I get some help? I am stucked
1st attempt
After get an answer this is how I modify Company entity:
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;
class Company
{
    ...
    /**
     * @var Brand
     * @ORM\OneToMany(targetEntity="Brand", mappedBy="company", cascade={"persist"})
     **/
    protected $brands;
    public function __construct()
    {
        $this->brands = new ArrayCollection();
    }
    ...
    public function getBrands()
    {
        return $this->brands;
    }
    /**
     * Add brands
     *
     * @param Brand $brand
     * @return Brands
     */
    public function addBrand( Brand $brand)
    {
        $this->brands[] = $brand;
        return $this;
    }
    /**
     * Remove brands
     *
     * @param Brand $brand
     */
    public function removeBrand( Brand $brand)
    {
        $this->brands->removeElement($brand);
    }
}
But I am getting this error:
No entity manager defined for class Doctrine\Common\Collections\ArrayCollection
Why is that?
                        
You could try setting up your entities like this:
What we're defining here is that new
Brandscan be created from theCompanyentity withcascade={"persist"}.It's recommended you implement
addBrandandremoveBrandinCompanyfor direct interaction with theArrayCollection.A simple example of the final functionality:
EDIT
This is just an example, you may choose not to add with keys or even implement a remove function, but this is a starting point: