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Reference
Zend\Hydrator\Filter
Hydrator filters allow you to manipulate the behavior of the extract()
operation. This is especially useful, if you want to omit some internals (e.g.
getServiceManager()
) from the array representation.
It comes with a helpful Composite
implementation, and several filters for
common use cases. The filters are composed in the AbstractHydrator
, so you can
start using them immediately in any custom extensions you write that extend that
class.
namespace Zend\Hydrator\Filter;
interface FilterInterface
{
/**
* Should return true, if the given filter
* does not match
*
* @param string $property The name of the property
* @return bool
*/
public function filter($property);
}
If it returns true, the key/value pairs will be in the extracted arrays - if it returns false, you'll not see them again.
Filter implementations
Zend\Hydrator\Filter\GetFilter
This filter is used in the ClassMethods
hydrator to decide which getters will
be extracted. It checks if the key to extract starts with get
or the object
contains a method beginning with get
(e.g., Zend\Foo\Bar::getFoo
).
Zend\Hydrator\Filter\HasFilter
This filter is used in the ClassMethods
hydrator to decide which has
methods
will be extracted. It checks if the key to extract begins with has
or the
object contains a method beginning with has
(e.g., Zend\Foo\Bar::hasFoo
).
Zend\Hydrator\Filter\IsFilter
This filter is used in the ClassMethods
hydrator to decide which is
methods
will be extracted. It checks if the key to extract begins with is
or the
object contains a method beginning with is
(e.g., Zend\Foo\Bar::isFoo
).
Zend\Hydrator\Filter\MethodMatchFilter
This filter allows you to omit methods during extraction that match the
condition defined in the composite. The name of the method is specified in the
constructor of this filter; the second parameter decides whether to use white or
blacklisting to decide (whitelisting retains only the matching method, blacklist
omits any matching method). The default is blacklisting - pass false
to change
the behavior.
Zend\Hydrator\Filter\NumberOfParameterFilter
This filter is used in the ClassMethods
hydrator to check the number of
parameters. By convention, the get
, has
and is
methods do not get any
parameters - but it may happen. You can add your own number of required
parameters, simply add the number to the constructor. The default value is 0. If
the method has more or fewer parameters than what the filter accepts, it will be
omitted.
Remove filters
If you want to tell e.g. the ClassMethods
hydrator, to not extract methods that start with is
,
remove the related filter:
$hydrator = new ClassMethods(false);
$hydrator->removeFilter('is');
After performing the above, the key/value pairs for is
methods will not end up
in your extracted array anymore. The filters can be used in any hydrator, but
the ClassMethods
hydrator is the only one, that has pre-registered filters:
$this->filterComposite->addFilter('is', new IsFilter());
$this->filterComposite->addFilter('has', new HasFilter());
$this->filterComposite->addFilter('get', new GetFilter());
$this->filterComposite->addFilter(
'parameter',
new NumberOfParameterFilter(),
FilterComposite::CONDITION_AND
);
If these are not appropriate for your object, you can unregister them as shown in the previous example.
Add filters
You can add filters to any hydrator that extends the AbstractHydrator
. Filters
can either implement FilterInterface
, or simply be PHP callables:
$hydrator->addFilter('len', function($property) {
if (strlen($property) !== 3) {
return false;
}
return true;
});
By default, every filter you add will be added with a conditional or
. If you
want to add it with and
(as the NumberOfParameterFilter
that is added to the
ClassMethods
hydrator by default), provide the conditon as the third argument
to addFilter
:
$hydrator->addFilter('len', function($property) {
if (strlen($property) !== 3) {
return false;
}
return true;
}, FilterComposite::CONDITION_AND);
One common use case for filters is to omit getters for values that you do not want to represent, such as a service manager instance:
$hydrator->addFilter(
'servicemanager',
new MethodMatchFilter('getServiceManager'),
FilterComposite::CONDITION_AND
);
The example above will exclude the getServiceManager()
method and the
servicemanager
key from extraction, even if the get
filter wants to add it.
Use FilterComposite for complex filters
FilterComposite
implements FilterInterface
as well, so you can add it as
a regular filter to the hydrator. One benefit of this implementation is that you
can add the filters with a condition and accomplish complex requirements using
different composites with different conditions. You can pass the following
conditions to the 3rd parameter, when you add a filter:
Zend\Hydrator\Filter\FilterComposite::CONDITION_OR
At the given level of the composite, at least one filter in that condition block has to return true to extract the value.
Zend\Hydrator\Filter\FilterComposite::CONDITION_AND
At the given level of the composite, all filters in that condition block must return true to extract the value.
FilterComposite Examples
This composition will have a similar logic as the if below:
$composite = new FilterComposite();
$composite->addFilter('one', $condition1);
$composite->addFilter('two', $condition2);
$composite->addFilter('three', $condition3);
$composite->addFilter('four', $condition4, FilterComposite::CONDITION_AND);
$composite->addFilter('five', $condition5, FilterComposite::CONDITION_AND);
// This is what's happening internally
if (
($condition1
|| $condition2
|| $condition3
) && ($condition4
&& $condition5
)
) {
//do extraction
}
If you only have one condition (e.g., only an and
or or
) block, the other
one will be completely ignored.
A bit more complex filter can look like this:
$composite = new FilterComposite();
$composite->addFilter(
'servicemanager',
new MethodMatchFilter('getServiceManager'),
FilterComposite::CONDITION_AND
);
$composite->addFilter(
'eventmanager',
new MethodMatchFilter('getEventManager'),
FilterComposite::CONDITION_AND
);
$hydrator->addFilter('excludes', $composite, FilterComposite::CONDITION_AND);
// Internal
if (( // default composite inside the hydrator
($getFilter
|| $hasFilter
|| $isFilter
) && (
$numberOfParameterFilter
)
) && ( // new composite, added to the one above
$serviceManagerFilter
&& $eventManagerFilter
)
) {
// do extraction
}
If you perform this on the ClassMethods
hydrator, all getters will get
extracted, except for getServiceManager()
and getEventManager()
.
Using the provider interface
FilterProviderInterface
allows you to configure the behavior of the hydrator
inside your objects.
namespace Zend\Hydrator\Filter;
interface FilterProviderInterface
{
/**
* Provides a filter for hydration
*
* @return FilterInterface
*/
public function getFilter();
}
(The getFilter()
method is automatically excluded from extract()
.) If the
extracted object implements the Zend\Hydrator\Filter\FilterProviderInterface
,
the returned FilterInterface
instance can also be a FilterComposite
.
For example:
Class Foo implements FilterProviderInterface
{
public function getFoo()
{
return 'foo';
}
public function hasFoo()
{
return true;
}
public function getServiceManager()
{
return 'servicemanager';
}
public function getEventManager()
{
return 'eventmanager';
}
public function getFilter()
{
$composite = new FilterComposite();
$composite->addFilter('get', new GetFilter());
$exclusionComposite = new FilterComposite();
$exclusionComposite->addFilter(
'servicemanager',
new MethodMatchFilter('getServiceManager'),
FilterComposite::CONDITION_AND
);
$exclusionComposite->addFilter(
'eventmanager',
new MethodMatchFilter('getEventManager'),
FilterComposite::CONDITION_AND
);
$composite->addFilter('excludes', $exclusionComposite, FilterComposite::CONDITION_AND);
return $composite;
}
}
$hydrator = new ClassMethods(false);
$extractedArray = $hydrator->extract(new Foo());
$extractedArray
will only have 'foo' => 'foo'; all other values are
excluded from extraction.
Note
All pre-registered filters from the
ClassMethods
hydrator are ignored when this interface is used.
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