zend.filter.writing-filters.rst

Writing Filters

Zend\Filter supplies a set of commonly needed filters, but developers will often need to write custom filters for their particular use cases. The task of writing a custom filter is facilitated by implementing Zend\Filter\FilterInterface.

Zend\Filter\FilterInterface defines a single method, filter(), that may be implemented by user classes.

Example

The following example demonstrates how to write a custom filter:

namespace Application\Filter;

use Zend\Filter\FilterInterface;

class MyFilter implements FilterInterface
{
    public function filter($value)
    {
        // perform some transformation upon $value to arrive on $valueFiltered

        return $valueFiltered;
    }
}

To attach an instance of the filter defined above to a filter chain:

$filterChain = new Zend\Filter\FilterChain();
$filterChain->attach(new Application\Filter\MyFilter());