Implementing a Custom Pattern

For many implementations, you can use the default pattern objects supplied by this library. If your notifications have additional requirements, such as service-specific validation rules or additional required/optional fields, you can create your own pattern classes by subclassing the base pattern classes.

Adding a Simple Field

Suppose we want to add a field to an AnnounceEndorsement pattern to indicate a "time to live" (TTL) for the endorsement. This could represent the number of days for which the endorsement record is guaranteed to be available at the given identifier.

We would extend the AnnounceEndorsement class like this:

<?php
 
namespace coarnotify\patterns\announce_endorsement;
 
class AnnounceEndorsementWithTTL extends AnnounceEndorsement
{
    public function getTtl(): ?int
    {
        return $this->getProperty('ttl');
    }
 
    public function setTtl(int $value): void
    {
        $this->setProperty('ttl', $value);
    }
}

Now any AnnounceEndorsement notification containing a ttl field can be read and written using this object.

Extending the Validation

To validate the ttl field to ensure it contains a positive integer, we can hard-code the validation:

<?php
 
namespace coarnotify\patterns\announce_endorsement;
 
use coarnotify\exceptions\ValidationError;
 
class AnnounceEndorsementWithTTL extends AnnounceEndorsement
{
    public function getTtl(): ?int
    {
        return $this->getProperty('ttl');
    }
 
    public function setTtl(int $value): void
    {
        if ($value < 0) {
            throw new \InvalidArgumentException('ttl must be a positive integer');
        }
        $this->setProperty('ttl', $value);
    }
 
    public function validate(): bool
    {
        $ve = new ValidationError();
 
        try {
            parent::validate();
        } catch (ValidationError $superve) {
            $ve = $superve;
        }
 
        if ($this->getTtl() < 0) {
            $ve->addError('ttl', 'ttl must be a positive integer');
        }
 
        if ($ve->hasErrors()) {
            throw $ve;
        }
 
        return true;
    }
}

Alternatively, you can create a custom validator and add it to the validation ruleset:

<?php
 
namespace coarnotify\patterns;
 
use coarnotify\validate\Validator;
use coarnotify\exceptions\ValidationError;
 
class AnnounceEndorsementWithTTL extends AnnounceEndorsement
{
    private static function positiveInteger($value): bool
    {
        if (is_int($value) && $value > 0) {
            return true;
        }
        throw new \InvalidArgumentException('Value must be a positive integer');
    }
 
    public function __construct(array $properties = [], Validator $validator = null)
    {
        $rules = $validator ? $validator->getRules() : [];
        $rules['ttl'] = ['default' => [self::class, 'positiveInteger']];
        $customValidator = new Validator($rules);
 
        parent::__construct($properties, $customValidator);
    }
 
    public function getTtl(): ?int
    {
        return $this->getProperty('ttl');
    }
 
    public function setTtl(int $value): void
    {
        $this->setProperty('ttl', $value);
    }
 
    public function validate(): bool
    {
        $ve = new ValidationError();
 
        try {
            parent::validate();
        } catch (ValidationError $superve) {
            $ve = $superve;
        }
 
        $this->requiredAndValidate($ve, 'ttl', $this->getTtl());
 
        if ($ve->hasErrors()) {
            throw $ve;
        }
 
        return true;
    }
}

Adding a Complex/Nested Field

To customize fields nested in one of the pattern parts, override the pattern part with a custom implementation and wire it to the appropriate accessor on the pattern object.

For example, to add a custom object to the AnnounceEndorsement pattern:

namespace coarnotify\patterns\announce_endorsement;
 
use coarnotify\core\notify\NotifyObject;
use coarnotify\core\notify\NotifyProperties;
 
class AnnounceEndorsementObject extends NotifyObject
{
    public function getCustomField(): ?string
    {
        return $this->getProperty('custom_field');
    }
 
    public function setCustomField(string $value): void
    {
        $this->setProperty('custom_field', $value);
    }
}
 
class AnnounceEndorsementWithCustomObject extends AnnounceEndorsement
{
    public function getObject(): ?AnnounceEndorsementObject
    {
        $obj = $this->getProperty(NotifyProperties::OBJECT);
        if ($obj !== null) {
            return new AnnounceEndorsementObject($obj, false, $this->validateProperties, $this->validators, NotifyProperties::OBJECT);
        }
        return null;
    }
}

Now, when accessing the object property on an AnnounceEndorsementWithCustomObject instance, you get an instance of AnnounceEndorsementObject.