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Result Sets
Laminas\Db\ResultSet
is a sub-component of laminas-db for abstracting the iteration
of results returned from queries producing rowsets. While data sources for this
can be anything that is iterable, generally these will be populated from
Laminas\Db\Adapter\Driver\ResultInterface
instances.
Result sets must implement the Laminas\Db\ResultSet\ResultSetInterface
, and all
sub-components of laminas-db that return a result set as part of their API will
assume an instance of a ResultSetInterface
should be returned. In most cases,
the prototype pattern will be used by consuming object to clone a prototype of
a ResultSet
and return a specialized ResultSet
with a specific data source
injected. ResultSetInterface
is defined as follows:
use Countable;
use Traversable;
interface ResultSetInterface extends Traversable, Countable
{
public function initialize(mixed $dataSource) : void;
public function getFieldCount() : int;
}
Quick start
Laminas\Db\ResultSet\ResultSet
is the most basic form of a ResultSet
object
that will expose each row as either an ArrayObject
-like object or an array of
row data. By default, Laminas\Db\Adapter\Adapter
will use a prototypical
Laminas\Db\ResultSet\ResultSet
object for iterating when using the
Laminas\Db\Adapter\Adapter::query()
method.
The following is an example workflow similar to what one might find inside
Laminas\Db\Adapter\Adapter::query()
:
use Laminas\Db\Adapter\Driver\ResultInterface;
use Laminas\Db\ResultSet\ResultSet;
$statement = $driver->createStatement('SELECT * FROM users');
$statement->prepare();
$result = $statement->execute($parameters);
if ($result instanceof ResultInterface && $result->isQueryResult()) {
$resultSet = new ResultSet;
$resultSet->initialize($result);
foreach ($resultSet as $row) {
echo $row->my_column . PHP_EOL;
}
}
Laminas\Db\ResultSet\ResultSet and Laminas\Db\ResultSet\AbstractResultSet
For most purposes, either an instance of Laminas\Db\ResultSet\ResultSet
or a
derivative of Laminas\Db\ResultSet\AbstractResultSet
will be used. The
implementation of the AbstractResultSet
offers the following core
functionality:
namespace Laminas\Db\ResultSet;
use Iterator;
abstract class AbstractResultSet implements Iterator, ResultSetInterface
{
public function initialize(array|Iterator|IteratorAggregate|ResultInterface $dataSource) : self;
public function getDataSource() : Iterator|IteratorAggregate|ResultInterface;
public function getFieldCount() : int;
/** Iterator */
public function next() : mixed;
public function key() : string|int;
public function current() : mixed;
public function valid() : bool;
public function rewind() : void;
/** countable */
public function count() : int;
/** get rows as array */
public function toArray() : array;
}
Laminas\Db\ResultSet\HydratingResultSet
Laminas\Db\ResultSet\HydratingResultSet
is a more flexible ResultSet
object
that allows the developer to choose an appropriate "hydration strategy" for
getting row data into a target object. While iterating over results,
HydratingResultSet
will take a prototype of a target object and clone it once
for each row. The HydratingResultSet
will then hydrate that clone with the
row data.
The HydratingResultSet
depends on
laminas-hydrator, which you will
need to install:
$ composer require laminas/laminas-hydrator
In the example below, rows from the database will be iterated, and during
iteration, HydratingResultSet
will use the Reflection
based hydrator to
inject the row data directly into the protected members of the cloned
UserEntity
object:
use Laminas\Db\Adapter\Driver\ResultInterface;
use Laminas\Db\ResultSet\HydratingResultSet;
use Laminas\Hydrator\Reflection as ReflectionHydrator;
class UserEntity
{
protected $first_name;
protected $last_name;
public function getFirstName()
{
return $this->first_name;
}
public function getLastName()
{
return $this->last_name;
}
public function setFirstName($firstName)
{
$this->first_name = $firstName;
}
public function setLastName($lastName)
{
$this->last_name = $lastName;
}
}
$statement = $driver->createStatement($sql);
$statement->prepare($parameters);
$result = $statement->execute();
if ($result instanceof ResultInterface && $result->isQueryResult()) {
$resultSet = new HydratingResultSet(new ReflectionHydrator, new UserEntity);
$resultSet->initialize($result);
foreach ($resultSet as $user) {
echo $user->getFirstName() . ' ' . $user->getLastName() . PHP_EOL;
}
}
For more information, see the laminas-hydrator documentation to get a better sense of the different strategies that can be employed in order to populate a target object.