ZF2 Forms in Beta5

Forms are a nightmare for web development. They break the concept of separation of concerns:

  • They have a display aspect (the actual HTML form)
  • They have a validation aspect
  • And the two mix, as you need to display validation error messages.

On top of that, the submitted data is often directly related to your domain models, causing more issues:

  • Not all elements will have a 1:1 mapping to the domain model -- buttons, CSRF protection, CAPTCHAs, etc. usually are application-level concerns, but not domain issues.
  • Names valid for your domain model may not be valid names for HTML entities.

Add to this that the validation logic may be re-usable outside of a forms context, and you've got a rather complex problem.

Forms in ZF2

Starting in 2.0.0beta4, we offerred a completely rewritten Form component. In fact, it's not just a Form component -- a new component, InputFilter, was also added. InputFilter is a component that provides re-usable validation and normalization logic, and can be used with forms or your domain model. The Form component is basically a bridge between domain models/validation and the view layer.

However, this means a bit more complexity for the end-user. You now must:

  • Create your form, which consists of elements and fieldsets.
  • Create an input filter, consisting of inputs.
  • Inform the form of the input filter.

It's a bit of work. And there's more: we wanted to simplify the process of getting your validated values into your domain objects. For this, we added a concept of hydrators, which map the validated form values to an object you bind to the form. Now you have three pieces to keep track of -- form (and its elements), input filter (and its inputs), and a hydrator.

So, a few developers had an idea: use annotations on the domain model objects to define these items, letting you keep it all in one place.

While I'm not normally a fan of annotations, I immediately saw the appeal in this particular situation.

An Example

Let's consider a very simple example. The following domain object represents data for a user, and includes a variety of elements we'd represent in a form.

namespace MyVendor\Model;

use Zend\Form\Annotation;

 * @Annotation\Hydrator("Zend\Stdlib\Hydrator\ObjectProperty")
 * @Annotation\Name("user")
class User
     * @Annotation\Attributes({"type":"text" })
     * @Annotation\Validator({"type":"Regex","options":{"regex":"/^[a-zA-Z][a-zA-Z0-9_-]{1,19}/"}})
     * @Annotation\Options({"label":"Username:"})
    public $username;

     * @Annotation\Required(false)
     * @Annotation\Attributes({"type":"text" })
     * @Annotation\Options({"label":"Your full name:"})
    public $fullname;

     * @Annotation\Type("Zend\Form\Element\Email")
     * @Annotation\Options({"label":"Your email address:"})
    public $email;

     * @Annotation\Type("Zend\Form\Element\Url")
     * @Annotation\Options({"label":"Your home page:"})
    public $uri;

So, what does the above do?

  • The "name" annotation gives a form or element a specific name.
  • The "attributes" annotation indicates what attributes to compose into the form or element.
  • Similarly, the "options" annotation specifies options to compose into an element. These typically include the label, but may include other configuration that doesn't have an exact analog in the HTML attributes.
  • The "validator" annotation indicates a validator to compose for the input for a given element. We also ship a "filter" annotation.
  • The "type" annotation indicates a class to use for that particular form or element. In the specific cases used above, the elements actually provide default filters and validators, simplifying setup further!
  • Last, but not least, the "hydrator" annotation indicates a Zend\Stdlib\Hydrator implementation to use to relay data between the form and the object. I'll cover this more shortly.

So, let's now turn to creating a form and consuming it.

use MyVendor\Model\User;
use Zend\Form\Annotation\AnnotationBuilder;

$user    = new User();
$builder = new AnnotationBuilder();
$form    = $builder->createForm($user);

if ($form->isValid()) {
    // $user is now populated!
    echo $form->username;
} else {
    // probably need to render the form now.

You're not quite done, really -- most likely, you'll need to include a submit button of some sort, and it's always good practice to include a token to prevent CSRF injections. But with the above, you've accomplished the major headaches of setting up a form -- and using the data -- with minimal fuss.

Much more!

The form support in ZF2 offers a ton of other features, some of which are not specific to forms even.

  • ZF2 supports a variety of hydration strategies, which allow you to pass data to and from objects. The example above uses one that suggests a 1:1 mapping between the inputs and the object properties; other strategies include using ArrayObject, using class mutator methods, and more.

    At this point, you can hydrate an entire form, as well as individual fieldsets!

  • You can provide custom annotations. While this feature is not documented yet, you can tell the AnnotationBuilder about additional annotation classes, as well as provide listeners for those annotations so that they can interact with the form construction process. As an example, one contributor has already used these features to utilize Doctrine annotations to inform the builder about the name of a property, as well as indicate validators. (Side note: ZF2 now uses Doctrine's annotation syntax and parser by default.)

  • There are a number of features targetting collections, so that your client-side code can return arbitrary numbers of a specific fieldset type (e.g., collecting addresses for an applicant), and the form will be able to validate each. You can read more about those features from the author himself.

These features are all now available starting with the newly released 2.0.0beta5 version, which you can grab from the ZF2 packages site.

I'm really excited with the solutions we've created in ZF2, and even more excited to see people put them to use!

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