教义复合键

Question

I have these 3 table

"Business" with these fields: Id, Name, etc.. "City" with these fields: Id, Name, etc..

And then I have a table called BusinessCity (given that a bussines can be related to many cities). This table has the fields "BusinessId" and "CityId".

Im trying to relate the CityId to the City entity, and BusinessId to the business entity, on the class BusinessCity. I've been googling this for the past 3 days and couldnt find an answer, if this has been asked before im sorry i didnt see it. Could anyone help me or give me some pointers on how to get this done. Thanks in advance

Answer 1

What you are trying to achieve is a bi-directional many-to-many relation with a joinTable.

Many businesses can reside in multiple cities and in one city there can be multiple businesses.

In a many-to-many relationship either side can be the owning side. JoinTable definition can be left out and has sensible defaults but if you want to specify it concretely i included it in the example.

Business (in this example: owning side = inversedBy = JoinTable definition)

/**
 * @ORM\ManyToMany(targetEntity="Your/Bundle/City", inversedBy="businesses",cascade="{persist,merge}" fetch="EAGER")
 * @ORM\JoinTable(name="BusinessCity",
 *    joinColumns={@JoinColumn(name="business_id", referencedColumnName="id")},
 *    inverseJoinColumns={@JoinColumn(name="city_id", referencedColumnName="id")}
 *  )
 */
protected $cities;

public function __construct()
{
   $this->cities = new ArrayCollection();
}

public function getCities()
{
   return $this->cities;
}

public function setCities(Collection $cities)
{
   // using map with closure to have dublicate/type-checking provided by addCity
   $this->cities->map(function($city) {
       $this->addCity($city);
   });

   return $this;
}

public function addCity(CityInterface $city)
{
    // ... you don't want dublicates in your collection
    if (!$this->cities->contains($city)) {
       $this->cities->add($city);
    }

   return $this;
}

public function removeCity(CityInterface $city)
{
    $this->cities->removeElement($city);

    return $this;
}
// other properties and methods ..

City (inverse side = mappedBy)

/**
 * @ORM\ManyToMany(targetEntity="Your/Bundle/Business", mappedBy="cities")
 */
protected $businesses;

// getters & setters ...
// other properties and methods ...