Symfony Array Collection as Entity Property

From your description it seems that Household and PetType has a cardinality of m-to-one; that means that an Household record could have only a PetType while a PetType could be associated to more than one Household record.

From DB point of view that means foreign key into Household table. If you want to make possible a "multiple" connection between Household and PetType, you have to modify your relationship between entities.

Just an example (disclaimer: your entities could be named differently and I didn't test this code. I'm explaining here a concept, not working on runnable code as your example didn't came with snippet examples)

class Household 
{
  //some properties

  /**
   * @ORM\ManyToMany(targetEntity="PetType", inversedBy="households")
   * @ORM\JoinTable(name="household_pettype")
   */
  $pet_types;

  //some methods

  public function addPetType(PetType $petType)
  {
    $this->pet_types[] = $petType;

    return $this;
  }

  public function setPetTypes(ArrayCollection $petTypes)
  {
    $this->pet_types = $petTypes;

    return $this;
  }

  public function removePetType(PetType $petType)
  {
    $this->pet_types->removeElement($petType);
  }

  public function getPetTypes()
  {
    return $this->pet_types;
  }
}

class PetType
{
  //some properties

  /**
   * @ORM\ManyToMany(targetEntity="Household", mappedBy="pet_types")
   */
   $households;

  //some methods

  public function addHousehold(Household $household)
  {
    $this->households[] = $household;

    return $this;
  }

  public function setHouseholds(ArrayCollection $households)
  {
    $this->households = $households;

    return $this;
  }

  public function removeHousehold(Household $household)
  {
    $this->households->removeElement($household);
  }

  public function getHousehold()
  {
    return $this->households;
  }
}

After that you need to run again

php app/consolle doctrine:schema:update --force

This will update your DB schema and, because new cardinality is m-to-n, a relationship table named household_pettype will be created (that will hold only foreign keys from other two tables)

After that you could alternatively use two methods (from household point of view)

• ->addPetType($petType); that will append a PetType object to Household collection
• ->setPetTypes($petTypeArrayCollection); that will set in a shot all PetTypes