DateTimeFormatterStrategy passes special characters used by date_create_from_format to date_format

[boesing]

Hey guys,

I would like to use special chars for the date format, e.g. to ensure that if I pass a MySQL date string to the hydrator, an object with time reset to 0 is being returned.

Therefore, I had to strip un-escaped special chars (*, !, | and +) (documentation) from the format being passed to the DateTimeInterface::format method.

[weierophinney]

I guess I just don't quite understand the purpose of this. Why would the format you provide to the DateTimeFormatterStrategy contain these characters?

Additionally, this feels very much like a project-specific requirement which could be handled by either:

• Decoration (likely by decorating the constructor to filter the format before assignment)
• Domain-level code that triggers before creating the strategy instance.

I need more background to assess whether this is something we want to support.

[weierophinney]

For those reviewing the issue later to understand what it does, the above matches an of the characters +|!* NOT preceded by a \\.

[malukenho]

Why we don't accept DateTimeInterface @weierophinney?

[weierophinney]

@malukenho We do as of #70. ;-)

[boesing]

@weierophinney Well, the thing is, if you use the Strategies to e.g. transport data via JSON by an API, the clients hydrate that value back into a datetime object and always uses the the current time if neither "!" at the beginning or "|" at the end is specified. This actually is pretty annoying if you want to use a date for comparison reasons.

Lets assume the following example with the current time (10:14 pm):

$data = [
    'birthdate' => (new DateTime('-18 years'))->format('Y-m-d'),
];

$user = new class
{

    /**
     * @var DateTime
     */
    public $birthdate;

    public function isEighteen(): bool
    {
        $today = new DateTime();
        $diff = $this->birthdate->diff($today, true);

        return $diff->y >= 18;
    }

    public function wasEighteen(DateTime $specificDate): bool
    {
        $diff = $this->birthdate->diff($specificDate, true);

        return $diff->y >= 18;
    }
};

$hydrator = new Zend\Hydrator\Reflection;
$hydrator->addStrategy('birthdate', new Zend\Hydrator\Strategy\DateTimeFormatterStrategy('Y-m-d'));
$hydrator->hydrate($data, $user);

var_dump($user->isEighteen());
var_dump($user->wasEighteen(new DateTime('-5 minutes')));

bool(true)
bool(false)

Ofcourse, the user was already 18 even 5 minutes ago.
If I would use DateTimeFormatterStrategy('Y-m-d|'), the strategy would hydrate the birthdate without the current time set to that object. Yes, I could change the business logic and force that user::birthdate->setTime(0,0) by myself, but I actually dont see any disadvantages of parsing the format during extraction.

[boesing]

So, is there any possibility that this change is being merged? If not, please feel free to either close this PR or give me a short feedback.
I am still struggling with that problem and probably need to replace all zend-hydrator DateTimeFormatterStrategy usages within our code if this aint going forward.

Thanks in advance.

[weierophinney]

Thanks for the explanation, @boesing !

The only change I'd ask for now is a note in the documentation detailing that you can do this when you need to be concerned about comparisons.