Zend Framework 2 Doctrine2 leftJoin creating a separate SELECT query - php

Question

Does anyone know why the Doctrine query below creates a separate join for the StandardDedescribed entity?
As you can see below this query pulls the information from the master entity 'EquipmentUK' and two related tables: 'SchemaInfo' and 'StandardDescribed'. It works well for the SchemaInfo, but creates another query for StandardDescribed. The relations in the Entities seem to be coded extactly the same, so I don't understand why it behaves differently for StandardDescribed?
$qb->select('e')
->from('\Lookup\Entity\Fullhistory\EquipmentUK', 'e')
->leftJoin(
'\Lookup\Entity\Fullhistory\SchemaInfo',
'si',
Expr\Join::WITH,
'e.schema_id = si.schema_id AND si.parent_schema_id != si.schema_id'
)
->leftJoin(
'\Lookup\Entity\Intelligence\StandardDescribedUK',
'sd',
Expr\Join::WITH,
'e.schema_id = sd.schema_id'
)
->where($qb->expr()->eq('e.vehicle_id', '?1'))
->setParameter(1, $jatoid);
Here are the Entities:
EquipmentUK:
namespace Lookup\Entity\Fullhistory;
use Doctrine\ORM\Mapping as ORM;
/**
* EquipmentUK
*
* #ORM\Table(name="equipment",
* uniqueConstraints={
* #ORM\UniqueConstraint(name="search_idx", columns={"vehicle_id", "option_id", "record_id", "schema_id"})
* }
* )
* #ORM\Entity
*/
class EquipmentUK
{
/**
* #var integer
*
* #ORM\Id
* #ORM\Column(type="integer")
*/
private $vehicle_id;
/**
* #var integer
*
* #ORM\Id
* #ORM\Column(type="integer")
*/
private $schema_id;
/**
* #var integer
*
* #ORM\Id
* #ORM\Column(type="integer")
*/
private $option_id;
/**
* #var integer
*
* #ORM\Id
* #ORM\Column(type="integer")
*/
private $record_id;
/**
* #var string
*
* #ORM\Column(type="string")
*/
private $location;
/**
* #ORM\ManyToOne(targetEntity="Lookup\Entity\Fullhistory\SchemaInfo", cascade={"all"}, fetch="EAGER")
* #ORM\JoinColumn(name="schema_id", referencedColumnName="schema_id")
*/
private $schemaInfo;
/**
* #ORM\ManyToOne(targetEntity="Lookup\Entity\Intelligence\StandardDescribedUK", cascade={"all"}, fetch="EAGER")
* #ORM\JoinColumn(name="schema_id", referencedColumnName="schema_id")
*/
private $standardDescribed;
/**
* #var string
*
* #ORM\Column(type="string")
*/
private $data_value;
public function getVehicleId()
{
return $this->vehicle_id;
}
public function getSchemaId()
{
return $this->schema_id;
}
public function getOptionId()
{
return $this->option_id;
}
public function getRecordId()
{
return $this->record_id;
}
public function getLocation()
{
return $this->location;
}
public function getSchemaInfo()
{
return $this->schemaInfo;
}
public function getStandardDescribed()
{
return $this->standardDescribed;
}
public function getDataValue()
{
return $this->data_value;
}
}
SchemaInfo:
namespace Lookup\Entity\Fullhistory;
use Doctrine\ORM\Mapping as ORM;
/**
* SchemaInfo
*
* #ORM\Table(name="schema_info")
* #ORM\Entity
*/
class SchemaInfo
{
/**
* #var integer
*
* #ORM\Column(name="schema_id", type="integer", nullable=false)
* #ORM\Id
* #ORM\GeneratedValue(strategy="IDENTITY")
*/
private $schema_id;
/**
* #var integer
*
* #ORM\Column(name="parent_schema_id", type="integer", nullable=true)
*/
private $parent_schema_id;
/**
* #var integer
*
* #ORM\Column(name="location_schema_id", type="integer", nullable=true)
*/
private $locationSchemaId;
/**
* #var integer
*
* #ORM\Column(name="scale_of_data", type="smallint", nullable=true)
*/
private $scaleOfData;
/**
* #var integer
*
* #ORM\Column(name="data_type", type="smallint", nullable=true)
*/
private $dataType;
public function getSchemaId()
{
return $this->schema_id;
}
public function getParentSchemaId()
{
return $this->parent_schema_id;
}
}
StandardDescribedUK
namespace Lookup\Entity\Intelligence;
use Doctrine\ORM\Mapping as ORM;
/**
* StandardDescribedUK
*
* #ORM\Table(name="jato_uk_intelligence.standard_described")
* #ORM\Entity
*/
class StandardDescribedUK
{
/**
* #var integer
*
* #ORM\Id
* #ORM\Column(type="integer")
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $schema_id;
/**
* #var string
*
* #ORM\Column(name="category", type="string", nullable=true)
*/
private $category;
public function getCategory()
{
return $this->category;
}
}

Answer 1

Your joins should use Doctrine's own relational schema: your EquipmentUK has declared its relation with SchemaInfo via the property $schemaInfo, and it has also declared its relation with StandardDescribedUK via $standardDescribed. So:
$qb->select('e')
->from('\Lookup\Entity\Fullhistory\EquipmentUK', 'e')
->leftJoin(
'e.schemaInfo',
'si'
//we don't need that third param as the relation is already known
)
->leftJoin(
'e.standardDescribed',
'sd'
//same here, no need for explicit relation
)
->where($qb->expr()->eq('e.vehicle_id', ':vehicle'))
//this here is a restriction, should be in WHERE instead of ON
->andWhere($qb->expr()->neq('si.parent_schema_id', 'si.schema_id'))
->setParameter('vehicle', $jatoid);
Hope this helps!