src/Illuminate/Database/Eloquent/Relations/BelongsTo.php
<?php
namespace Illuminate\Database\Eloquent\Relations;
use BackedEnum;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Database\Eloquent\Collection;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\Concerns\ComparesRelatedModels;
use Illuminate\Database\Eloquent\Relations\Concerns\InteractsWithDictionary;
use Illuminate\Database\Eloquent\Relations\Concerns\SupportsDefaultModels;
class BelongsTo extends Relation
{
use ComparesRelatedModels,
InteractsWithDictionary,
SupportsDefaultModels;
/**
* The child model instance of the relation.
*
* @var \Illuminate\Database\Eloquent\Model
*/
protected $child;
/**
* The foreign key of the parent model.
*
* @var string
*/
protected $foreignKey;
/**
* The associated key on the parent model.
*
* @var string
*/
protected $ownerKey;
/**
* The name of the relationship.
*
* @var string
*/
protected $relationName;
/**
* Create a new belongs to relationship instance.
*
* @param \Illuminate\Database\Eloquent\Builder $query
* @param \Illuminate\Database\Eloquent\Model $child
* @param string $foreignKey
* @param string $ownerKey
* @param string $relationName
* @return void
*/
public function __construct(Builder $query, Model $child, $foreignKey, $ownerKey, $relationName)
{
$this->ownerKey = $ownerKey;
$this->relationName = $relationName;
$this->foreignKey = $foreignKey;
// In the underlying base relationship class, this variable is referred to as
// the "parent" since most relationships are not inversed. But, since this
// one is we will create a "child" variable for much better readability.
$this->child = $child;
parent::__construct($query, $child);
}
/**
* Get the results of the relationship.
*
* @return mixed
*/
public function getResults()
{
if (is_null($this->getForeignKeyFrom($this->child))) {
return $this->getDefaultFor($this->parent);
}
return $this->query->first() ?: $this->getDefaultFor($this->parent);
}
/**
* Set the base constraints on the relation query.
*
* @return void
*/
public function addConstraints()
{
if (static::$constraints) {
// For belongs to relationships, which are essentially the inverse of has one
// or has many relationships, we need to actually query on the primary key
// of the related models matching on the foreign key that's on a parent.
$table = $this->related->getTable();
$this->query->where($table.'.'.$this->ownerKey, '=', $this->getForeignKeyFrom($this->child));
}
}
/**
* Set the constraints for an eager load of the relation.
*
* @param array $models
* @return void
*/
public function addEagerConstraints(array $models)
{
// We'll grab the primary key name of the related models since it could be set to
// a non-standard name and not "id". We will then construct the constraint for
// our eagerly loading query so it returns the proper models from execution.
$key = $this->related->getTable().'.'.$this->ownerKey;
$whereIn = $this->whereInMethod($this->related, $this->ownerKey);
$this->whereInEager($whereIn, $key, $this->getEagerModelKeys($models));
}
/**
* Gather the keys from an array of related models.
*
* @param array $models
* @return array
*/
protected function getEagerModelKeys(array $models)
{
$keys = [];
// First we need to gather all of the keys from the parent models so we know what
// to query for via the eager loading query. We will add them to an array then
// execute a "where in" statement to gather up all of those related records.
foreach ($models as $model) {
if (! is_null($value = $this->getForeignKeyFrom($model))) {
$keys[] = $value;
}
}
sort($keys);
return array_values(array_unique($keys));
}
/**
* Initialize the relation on a set of models.
*
* @param array $models
* @param string $relation
* @return array
*/
public function initRelation(array $models, $relation)
{
foreach ($models as $model) {
$model->setRelation($relation, $this->getDefaultFor($model));
}
return $models;
}
/**
* Match the eagerly loaded results to their parents.
*
* @param array $models
* @param \Illuminate\Database\Eloquent\Collection $results
* @param string $relation
* @return array
*/
public function match(array $models, Collection $results, $relation)
{
// First we will get to build a dictionary of the child models by their primary
// key of the relationship, then we can easily match the children back onto
// the parents using that dictionary and the primary key of the children.
$dictionary = [];
foreach ($results as $result) {
$attribute = $this->getDictionaryKey($this->getRelatedKeyFrom($result));
$dictionary[$attribute] = $result;
}
// Once we have the dictionary constructed, we can loop through all the parents
// and match back onto their children using these keys of the dictionary and
// the primary key of the children to map them onto the correct instances.
foreach ($models as $model) {
$attribute = $this->getDictionaryKey($this->getForeignKeyFrom($model));
if (isset($dictionary[$attribute])) {
$model->setRelation($relation, $dictionary[$attribute]);
}
}
return $models;
}
/**
* Associate the model instance to the given parent.
*
* @param \Illuminate\Database\Eloquent\Model|int|string|null $model
* @return \Illuminate\Database\Eloquent\Model
*/
public function associate($model)
{
$ownerKey = $model instanceof Model ? $model->getAttribute($this->ownerKey) : $model;
$this->child->setAttribute($this->foreignKey, $ownerKey);
if ($model instanceof Model) {
$this->child->setRelation($this->relationName, $model);
} else {
$this->child->unsetRelation($this->relationName);
}
return $this->child;
}
/**
* Dissociate previously associated model from the given parent.
*
* @return \Illuminate\Database\Eloquent\Model
*/
public function dissociate()
{
$this->child->setAttribute($this->foreignKey, null);
return $this->child->setRelation($this->relationName, null);
}
/**
* Alias of "dissociate" method.
*
* @return \Illuminate\Database\Eloquent\Model
*/
public function disassociate()
{
return $this->dissociate();
}
/**
* Add the constraints for a relationship query.
*
* @param \Illuminate\Database\Eloquent\Builder $query
* @param \Illuminate\Database\Eloquent\Builder $parentQuery
* @param array|mixed $columns
* @return \Illuminate\Database\Eloquent\Builder
*/
public function getRelationExistenceQuery(Builder $query, Builder $parentQuery, $columns = ['*'])
{
if ($parentQuery->getQuery()->from == $query->getQuery()->from) {
return $this->getRelationExistenceQueryForSelfRelation($query, $parentQuery, $columns);
}
return $query->select($columns)->whereColumn(
$this->getQualifiedForeignKeyName(), '=', $query->qualifyColumn($this->ownerKey)
);
}
/**
* Add the constraints for a relationship query on the same table.
*
* @param \Illuminate\Database\Eloquent\Builder $query
* @param \Illuminate\Database\Eloquent\Builder $parentQuery
* @param array|mixed $columns
* @return \Illuminate\Database\Eloquent\Builder
*/
public function getRelationExistenceQueryForSelfRelation(Builder $query, Builder $parentQuery, $columns = ['*'])
{
$query->select($columns)->from(
$query->getModel()->getTable().' as '.$hash = $this->getRelationCountHash()
);
$query->getModel()->setTable($hash);
return $query->whereColumn(
$hash.'.'.$this->ownerKey, '=', $this->getQualifiedForeignKeyName()
);
}
/**
* Determine if the related model has an auto-incrementing ID.
*
* @return bool
*/
protected function relationHasIncrementingId()
{
return $this->related->getIncrementing() &&
in_array($this->related->getKeyType(), ['int', 'integer']);
}
/**
* Make a new related instance for the given model.
*
* @param \Illuminate\Database\Eloquent\Model $parent
* @return \Illuminate\Database\Eloquent\Model
*/
protected function newRelatedInstanceFor(Model $parent)
{
return $this->related->newInstance();
}
/**
* Get the child of the relationship.
*
* @return \Illuminate\Database\Eloquent\Model
*/
public function getChild()
{
return $this->child;
}
/**
* Get the foreign key of the relationship.
*
* @return string
*/
public function getForeignKeyName()
{
return $this->foreignKey;
}
/**
* Get the fully qualified foreign key of the relationship.
*
* @return string
*/
public function getQualifiedForeignKeyName()
{
return $this->child->qualifyColumn($this->foreignKey);
}
/**
* Get the key value of the child's foreign key.
*
* @return mixed
*/
public function getParentKey()
{
return $this->getForeignKeyFrom($this->child);
}
/**
* Get the associated key of the relationship.
*
* @return string
*/
public function getOwnerKeyName()
{
return $this->ownerKey;
}
/**
* Get the fully qualified associated key of the relationship.
*
* @return string
*/
public function getQualifiedOwnerKeyName()
{
return $this->related->qualifyColumn($this->ownerKey);
}
/**
* Get the value of the model's associated key.
*
* @param \Illuminate\Database\Eloquent\Model $model
* @return mixed
*/
protected function getRelatedKeyFrom(Model $model)
{
return $model->{$this->ownerKey};
}
/**
* Get the value of the model's foreign key.
*
* @param \Illuminate\Database\Eloquent\Model $model
* @return mixed
*/
protected function getForeignKeyFrom(Model $model)
{
$foreignKey = $model->{$this->foreignKey};
return $foreignKey instanceof BackedEnum ? $foreignKey->value : $foreignKey;
}
/**
* Get the name of the relationship.
*
* @return string
*/
public function getRelationName()
{
return $this->relationName;
}
}