.. include:: /Includes.rst.txt

.. _validating-domain-objects:

Validating domain objects
=========================

We have discussed both Extbase and Fluid in some detail, but have spent
very little time discussing the domain and how we go about ensuring its consistency. We often assume that
domain objects are consistent and adhere to our rules at all times.
Unfortunately, this is not achieved automatically. So it is important to define these
rules explicitly. In the blog example for example we can create the following
rules:

* The field ``username`` and ``password`` of the
  user object must have at least 5 characters. Furthermore the username
  must not contain special characters.
* The field ``email`` of the user object must contain a valid email address.

These rules must apply at all times for the user object. A user object is only valid if
it complies to these validation rules.
These rules are called *invariants* because they must be
valid during the entire lifetime of the object.

At the beginning of your project, it is important to consider which invariants your domain
objects will consist of. The next stage is to add these invariants to Extbase
in an appropriate way. Extbase provides *validators* for
checking the invariants - these are PHP classes in which the invariants are
implemented in code.

We will show you in the following example how you can use a validator for the
checking of invariants and how you can give the user the ability to
correct an error if and when it occurs.


Validators for checking of Invariants
-------------------------------------

A validator is a PHP class that has to check a certain invariant. All
validators that are used in Extbase extensions have to implement the interface
:php:`\TYPO3\CMS\Extbase\Validation\Validator\ValidatorInterface`.
The interface requires validators to implement two methods:

- :php:`validate($value)`
- :php:`getOptions()`

The main method is `validate`, which is called by the framework.
The value which is to be validated is passed along to said method and it's the
validator's job to check if that value is valid.

.. note::

    Although the interface states, that the method `validate` should return
    a :php:`\TYPO3\CMS\Extbase\Error\Result` object, it's not common practice to do
    so because most people who create custom validators extend the class
    :php:`\TYPO3\CMS\Extbase\Validation\Validator\AbstractValidator`.

    This enables you to call the addError()` method and let the abstract
    validator take care of returning a proper result object to the validation
    framework.

If the logic of your validator allows for loose/variable validation checks,
validator options might come in handy. Extbase ships with a :php:`StringLength`
validator which offers the options `minimum` and `maximum` that
let you define the string length the validator should use to check the incoming
value against.

.. tip::

    You will find the complete reference of the
    :php:`ValidatorInterface` in the :ref:`validation-api`.

For example, a validator which checks whether the passed string is
an email address looks like this:

::

    public function validate($value)
    {
        if (!is_string($value) || !$this->validEmail($value)) {
            $this->addError(
                $this->translateErrorMessage(
                    'validator.emailaddress.notvalid',
                    'extbase'
                ), 1221559976);
        }
    }

    protected function validEmail($emailAddress)
    {
        return \TYPO3\CMS\Core\Utility\GeneralUtility::validEmail($emailAddress);
    }

If ``$value`` is neither a string nor a valid email address, the validator
adds an error by calling `$this->addError()`.

.. tip::

    The method ``addError()`` expects an error message and an
    error code. The latter should be unique, therefore we recommend to use
    the UNIX timestamp of the creation time of the source code. With the
    help of the error code the error can be definitely identified, for
    example in bug reports.

By default, Extbase will not call your validator if the value to validate is
empty. This is configured through the property ``$acceptsEmptyValues`` which is
set to ``true`` by default.

In the package
:php:`\TYPO3\CMS\Extbase\Validation\Validator\*` Extbase offers
many validators for default requirements like the validation of emails,
numbers and strings.



When does validation take place?
--------------------------------

Domain objects in Extbase are validated only at one point in time:
When they get inserted into a controller action. With the help of figure
9-1 we can show what happens before the action is called.

.. figure:: /Images/9-CrosscuttingConcerns/figure-9-1.png
    :align: center

    Figure 9-1: Data flow of a request before the action is called

When a user sends a request, Extbase first determines which action
within the controller is responsible for this request. As Extbase knows
the names and types of the arguments of the action it can create objects
from the incoming data. This operation will be described in detail in the
section "Argument mapping" later on. Now the main step for us is as
follows: The created objects are to be validated. That is the invariants
must be checked. If all arguments are successfully validated, the
requested action of the extension is called and it can continue processing
the given objects. For example, it might pass it to the view ready for displaying.

.. tip::

    Certainly it would be helpful if the validation is also be done
    during the persisting of the objects to the database. At the moment it
    is not done since the data is stored in the database after sending the
    answer back to the browser. Therefore the user could not be informed in
    case of validating errors. In the meantime a second validating when
    persisting the objects is built into FLOW, so this will be expected in
    Extbase in the medium term.

When an error occurs during validation, the method
`errorAction()` of the current controller is
called. The default ``errorAction()`` redirects the user
to the last used form when possible, in order to give them a chance to
correct the errors.

.. tip::

    You may ask how the `errorAction()` knows
    which form was the last displayed one. This information is created by
    the ``form`` ViewHelper. He adds automatically the property
    ``__referrer`` to every generated form, which contains
    information about the current extension, controller and action
    combination. This data can be used by the
    `errorAction()` to display the erroneous form
    again.

Registering validators
----------------------

Now we know how validators are working and when they are called.
However we have to connect our domain model with the validators to define
which part of the model is has to be checked by which validator. Therefore
there are three possibilities which we define in the following:

* validating in the domain model with annotations
* validating in the domain model with our own validator class
* validating of controller arguments

Validating in the domain model with annotations
-----------------------------------------------
In most cases it is sufficient to validate the properties of a
domain object separately. When all properties are validated with success
the complete domain object is also successfully validated. When a property
can not be validated, the overall validation of the domain object
fails.

To define how a property of our domain object should be validated
we use *annotations* inside our source code.
Annotations are machine readable "annotations" in the source code that
are placed in comment blocks and start with the character
``@``.

For the validation the ``@TYPO3\CMS\Extbase\Annotation\Validate`` annotation is
available. With it we can specify which validator is to be used for
checking the annotated property. Let us take a look at this using part
of the domain model ``Post`` inside the blog example::

    <?php
    namespace MyVendor\BlogExample\Domain\Model;

    class Post extends \TYPO3\CMS\Extbase\DomainObject\AbstractEntity
    {
        /**
         * @var string
         * @TYPO3\CMS\Extbase\Annotation\Validate("StringLength", options={"minimum": 3, "maximum": 50})
         */
        protected $title;

        /**
         * @var string
         */
        protected $content;
    }

With the line ``@TYPO3\CMS\Extbase\Annotation\Validate("StringLength", options={"minimum": 3, "maximum": 50})``
the validator for the property ``$title`` is
specified. In parenthesis the parameters for the validator are also specified.
In our case we make sure that a title of a blog post is never shorter
than three characters and will never be longer than 50 characters.

Which validator class is to be used? Extbase looks for a validator
class using
``\TYPO3\CMS\Extbase\Validation\Validator\*ValidatorName*Validator``.
Using the above given annotation ``@TYPO3\CMS\Extbase\Annotation\Validate("StringLength")`` the
validator
:php:`\TYPO3\CMS\Extbase\Validation\Validator\StringLengthValidator`
is used.

When you have created your own validator to check the invariants
you can use it in the ``@TYPO3\CMS\Extbase\Annotation\Validate`` annotation using the full
class name.

Example::

    <?php
    namespace MyVendor\BlogExample\Domain\Model;

    class Post extends \TYPO3\CMS\Extbase\DomainObject\AbstractEntity
    {
        /**
         * @var string
         * @TYPO3\CMS\Extbase\Annotation\Validate("MyVendor\BlogExample\Domain\Validator\TitleValidator")
         */
        protected $title;

        /**
         * @var string
         */
        protected $content;
    }

Here we validate the property ``$title`` with the
:php:`\MyVendor\BlogExample\Domain\Validator\TitleValidator`.
This validator class now can check any invariants. For example, the
validator shown in the following listing checks whether the title of a
blog post is always built using the convention *Maintopic: Title*:

.. code-block:: php

   <?php

   namespace MyVendor\BlogExample\Domain\Validator;

   use TYPO3\CMS\Extbase\Validation\Validator\AbstractValidator;

   class TitleValidator extends AbstractValidator
   {
      protected function isValid($value)
      {
         // $value is the title string
         if (count(explode(':', $value)) >= 2) {
            return;
         }
         $this->addError('The title was not of the type [Topic]:[Title].', 1221563773);
      }
   }

Now you have seen how you can validate particular properties of
the domain model. The next section shows how complex domain
objects are validated.


Validating in the domain model with your own validator class
------------------------------------------------------------

The ability to register validators in the
model are especially useful when individual properties of the model
need to be validated. However, sometimes it is necessary to validate the
relationship between two or more properties of a model class. For
example for a user registration it is reasonable that in the user object
the property ``$password`` and ``$passwordConfirmed``
exists which should be identical. Therefore the individual validators
for ``$password`` respectively
``$passwordConfirmation`` can not help, because they have no
access to each other. You need an option to validate a domain object
*as a whole*.

For this you can create your own validator class for every object
in the domain model which validates the object as a whole and with it
has access to all object properties where possible.

Equipped with this knowledge we can implement a
``UserValidator`` which compares ``$password`` with
``$passwordConfirmation``. At first we must check if the given
object is of the type ``user`` - after all the validator can be
called with any object and has to add an error in such
case::

    <?php
    namespace MyVendor\ExtbaseExample\Domain\Validator;

    class UserValidator extends \TYPO3\CMS\Extbase\Validation\Validator\AbstractValidator
    {
        protected function isValid($user)
        {
            if (! $user instanceof \MyVendor\ExtbaseExample\Domain\Model\User) {
                $this->addError('The given Object is not a User.', 1262341470);
            }
        }
    }

If ``$user`` is not an instance of the user object an
error message is directly created with ``addError()``. The
validator does not validate the object any further.

.. tip::

    The method ``addError()`` gets two parameters - the
    first is an error message string while the second is an error number.
    The Extbase developers always uses the current UNIX timestamp when
    calling ``addError()``. By this it is secured that the
    validation errors can be unique identified.

Now we have created the foundation of our validator and can start
with the proper implementation of it - the check for equality between the
passwords. This is made quickly::

    <?php
    namespace MyVendor\ExtbaseExample\Domain\Validator;

    class UserValidator extends \TYPO3\CMS\Extbase\Validation\Validator\AbstractValidator
    {
        protected function isValid($user)
        {
            if (! $user instanceof \MyVendor\ExtbaseExample\Domain\Model\User) {
                $this->addError('The given Object is not a User.', 1262341470);
                return;
            }
            if ($user->getPassword() !== $user->getPasswordConfirmation()) {
                $this->addError('The passwords do not match.', 1262341707);
            }
        }
    }

Because we have access to the complete object the checking
for equality of ``$password`` and
``$passwordConfirmation`` is very straightforward.

Use the newly created validator by annotating the corresponding controller,
for example:

::

   <?php
   namespace MyVendor\ExtbaseExample\Controller;

   use MyVendor\ExtbaseExample\Domain\Model\User;
   use TYPO3\CMS\Extbase\Annotation as Extbase;
   use TYPO3\CMS\Extbase\Mvc\Controller\ActionController;

   class UserController extends ActionController
   {
      /**
       * @Extbase\Validate(param="user", validator="MyVendor\ExtbaseExample\Domain\Validator\UserValidator")
       */
      public function showAction(User $user)
      {
         // ...
      }
   }

Now we have got to know two possibilities how validators can be
registered for our domain objects: directly in the model via
``@TYPO3\CMS\Extbase\Annotation\Validate`` annotation for single properties and for complete
domain objects with an own validator class.

.. important::

   Up until version 10, extbase "magically" applied validators based on a naming
   convention. Starting with TYPO3 v10 all validators need to be explicitly registered.


The illustrated validators until now are always executed when a
domain model is given as parameter to a controller action - that is for
all actions. Sometimes it is desired to initiate the validation only
when calling special actions. How this can be done we will see in the
next section.



Validating of controller arguments
----------------------------------

If you want to validate a domain object only when calling a
special action you have to define validators for individual arguments.
Therefore a slightly modified form of the ``@TYPO3\CMS\Extbase\Annotation\Validate``
annotation can be used which is set in the comment block of the
controller action. It has the format ``@TYPO3\CMS\Extbase\Annotation\Validate
*[variablename] [validators]*``, in the example
below it is ``$pageName`` :php:`\MyVendor\MyExtension\Domain\Validator\PagenameValidator`::

    /**
     * Creates a new page with a given name.
     *
     * @param string $pageName THe name of the page which should be created.
     * @TYPO3\CMS\Extbase\Annotation\Validate("MyVendor\MyExtension\Domain\Validator\PageNameValidator", param="pageName")
     */
    public function createPageAction($pageName)
    {
        // ...
    }

Here the parameter ``$pageName`` is checked with its own
validator.


Interaction of validators
-------------------------

Now you know the possibilities how validators are to be
registered. For an argument of an action the following validators are
called:

* All ``@TYPO3\CMS\Extbase\Annotation\Validate`` annotations of the domain model are evaluated.
* Validators defined in the action with ``@TYPO3\CMS\Extbase\Annotation\Validate`` are called.

Lets have a look at the interaction once more with an
example::

    /**
     * Creates a website user for the given page name.
     *
     * @param string $pageName The name of the page where the user should be created.
     * @param \MyVendor\ExtbaseExample\Domain\Model\User $user The user which should be created.
     * @TYPO3\CMS\Extbase\Annotation\Validate(param="pageName", validator="TYPO3\CMS\Extbase\Validation\Validator\StringValidator")
     * @TYPO3\CMS\Extbase\Annotation\Validate("MyVendor\BlogExample\Domain\Validator\CustomUserValidator", param="user")
     */
    public function createUserAction($pageName, \MyVendor\ExtbaseExample\Domain\Model\User $user)
    {
        // ...
    }

For ``$user`` all ``@TYPO3\CMS\Extbase\Annotation\Validate`` annotations of the model are validated. Beyond that the validator
``\MyVendor\BlogExample\Domain\Validator\CustomUserValidator`` is used
to validate ``$user``.

In some use cases it is reasonable that *incomplete
domain objects* are given as arguments. That can be the case
for multi page forms, because after filling the first page the domain
object is not complete. In this case you can use the annotation
:php:`@TYPO3\CMS\Extbase\Annotation\IgnoreValidation("parameter")`. This
prevents the processing of the ``@TYPO3\CMS\Extbase\Annotation\Validate`` annotations in the
domain model and calling the validator class of the domain
object.

.. _case_study-edit_an_existing_object:

Case study: Edit an existing object
-----------------------------------

Now you know all the building blocks you need to edit a blog object with
a form. As of now, the edit form should be displayed again in case of a
validation error. Two actions are involved at editing the blog: The
``editAction`` shows the form with the blog to be edited and the
``updateAction`` saves the changes.

.. tip::

    If you want to implement edit forms for the domain objects of your
    extension you should implement it according to the schema displayed
    here.

The ``editAction`` for the blog looks like this::

    public function editAction(\MyVendor\BlogExample\Domain\Model\Blog $blog)
    {
        $this->view->assign('blog', $blog);
    }

The blog object that we want to edit is passed and given to the
view. The Fluid template than looks like this (slightly shortened and
reduced to the important)::

    <f:form name="blog" object="{blog}" action="update">
        <f:form.textfield property="title" />
        <f:form.textarea property="description" />
        <f:form.submit />
    </f:form>

Note that the ``blog`` object to be edited is bound to the
form with ``object="{blog}"``. With this you can reference a
property of the linked object with help of the ``property``
attribute of the form elements.

Also the name of the form (name="blog") is important because it is
used as a variable name for the object to be sent. When submitting the form
the ``updateAction`` is called with the ``blog`` object
as parameter.

::

    public function updateAction(\MyVendor\BlogExample\Domain\Model\Blog $blog)
    {
        $this->blogRepository->update($blog);
    }


So the name of the argument is ``$blog`` because the form
has the name blog. When no validation errors occur, the blog object will
be persisted with its changes.

Now have a look what happens when the user inserts erroneous data
into the form. In this case an error occurs when validating the
``$blog`` arguments. Therefore instead of the
`updateAction`, the
`errorAction` is called. This action routes the
request with ``forward()`` to the last used action because in
case of an error the form should be displayed again. Additionally, an error
message is generated and given to the controller. Ergo: In case of a
validation error the `editAction` is displayed
again.

As we want to display the erroneous object again it is important
that the ``updateAction`` and ``editAction`` use the
same argument names. In our example the argument is called
``$blog`` in both cases, so we are on the safe side.

Now we have another problem: The ``editAction``
validates all parameters, but our blog object is not valid - we are
trapped in an endless loop. Therefore we have to suppress the argument
validation for the ``editAction``. For this we need the annotation
:php:`@TYPO3\CMS\Extbase\Annotation\IgnoreValidation` – the comment block
of the ``editAction`` must be changed like this:

::

   <?php
   declare(strict_types = 1);

   namespace MyVendor\BlogExample\Controller;

   use TYPO3\CMS\Extbase\Annotation as Extbase;
   use TYPO3\CMS\Extbase\Mvc\Controller\ActionController;

   class BlogController extends ActionController
   {
       /**
        * @param \MyVendor\BlogExample\Domain\Model\Blog $blog The blog object
        * @Extbase\IgnoreValidation("blog")
        */
       public function editAction(\MyVendor\BlogExample\Domain\Model\Blog $blog)
       {
           $this->view->assign('blog', $blog);
       }
   }

Now the ``blog`` object is not validated in the
``editAction``. So also a non valid ``blog`` object is
displayed correct.

.. tip::

    If Extbase throws the exception
    \TYPO3\CMS\Extbase\Mvc\Exception\InfiniteLoopException it signs that the
    :php:`@TYPO3\CMS\Extbase\Annotation\IgnoreValidation` annotation is missing.

Fluid automatically adds the CSS class ``f3-form-error``
to all erroneous fields - so you can frame them in red for example using
CSS. There is also a ``flashMessages`` ViewHelper which outputs
the error messages of the validation.



Case study: Create an object
----------------------------

In the last section you have seen how to edit a blog object with a
form. Now we will show you how to create a new blog object with a form.
Also for creating a blog object two actions are involved. The
`newAction` shows a form for creating an object and
the `createAction` finally stores the
object.

The only difference to the editing of an object is that the
`newAction` is not always given an argument: when
first displaying the form it is logical that there is no object available
to be displayed. Therefore the argument must be marked as optional.

Here you will see all that we need. At first the controller
code:

::

   <?php
   declare(strict_types = 1);

   use TYPO3\CMS\Extbase\Annotation as Extbase;
   use TYPO3\CMS\Extbase\Mvc\Controller\ActionController;

   class BlogController extends ActionController
   {
       /**
        * This action shows the 'new' form for the blog.
        *
        * @param \MyVendor\BlogExample\Domain\Model\Blog $newBlog The optional default values
        * @Extbase\IgnoreValidation("newBlog")
        */
       public function newAction(\MyVendor\BlogExample\Domain\Model\Blog $newBlog = NULL)
       {
           $this->view->assign('newBlog', $newBlog);
       }

       /**
        * This action creates the blog and stores it.
        *
        * @param \MyVendor\BlogExample\Domain\Model\Blog $newBlog
        */
       public function createAction(\MyVendor\BlogExample\Domain\Model\Blog $newBlog)
       {
           $this->blogRepository->add($newBlog);
       }
   }

The Fluid template for the `newAction` looks
like this (in short form)::

    <f:flashMessages />
    <f:form name="newBlog" object="{newBlog}" action="create">
        <f:form.textfield property="title" />
        <f:form.textarea property="description" />
        <f:form.submit />
    </f:form>

What is the summary of what we have done? Again it is important
that the `newAction` and the
`createAction` have the same argument name. This
also has to conform with the name of the Fluid template
(``newBlog`` in the example). Also the parameter for the
`newAction` must be marked as optional and the
validation of the parameter must be suppressed with
:php:`@TYPO3\CMS\Extbase\Annotation\IgnoreValidation`. Finally you can
output validation errors in the template using the ``flashMessages``
ViewHelper when saving the data.

In figure 9-2 you can find an overview of the behavior of Extbase when
displaying, editing respectively creating of domain objects in the
frontend.

.. figure:: /Images/9-CrosscuttingConcerns/figure-9-2.png
    :align: center

    Figure 9-2: Data flow of the form display and saving. When a validating
    error occurs it is displayed again.

.. _mapping-arguments:

Mapping arguments
-----------------

In this section we will describe in detail what happens during a
request before the respective action is called, especially when sending a form.
Because the HTTP protocol (and PHP) can only transfer arrays and strings, a large array with data is transferred when
sending a form. In the action, domain objects are often expected as input
parameter, so somehow the array must become an object. That is done by
Extbase during the *Argument Mappings*. It
makes it possible that as a user of Extbase you not only work with
arrays, but you can change objects in forms or give over a complete object
as *parameter* in links.

Lets have a look at all of this in a concrete example: We pick up
the blog example extension and edit a blog object, like you got to know in
the last section ("Case study: Edit an existing object"). When you edit a
blog you see a form in which you can change the properties of the blog, in
our case ``title`` and ``description``.

The Fluid form looks like this (shortened to the essential)::

    <f:form method="post" action="update" name="blog" object="{blog}">
        <f:form.textfield property="title" />
        <f:form.textarea property="description" />
    </f:form>

If the form is submitted the data will be sent in the following
manner to the server::

    tx_blogexample_pi1[blog][__identity] = 5
    tx_blogexample_pi1[blog][title] = My title
    tx_blogexample_pi1[blog][description] = Description

First of all the data is tagged with a prefix that contains the name
of the extension and the plugin (``tx_blogexample_pi1``). This
makes sure that two extensions have no impact on each other. Furthermore
all changed properties of the blog object are transferred in an array, in
our case ``title`` and ``description``. As we want to
change a blog object, we also need the identity of the blog object. In
order to do this, Fluid automatically adds the ``__identity``
property for the ``blog`` object and fills it with the UID of the
blog.

Now on the server side a ``blog`` object must be created
out of this information. This is the job of the property mapper. Its
operation method is shown in figure 9-3.

For every argument it must be decided first whether a new object has
to be created or if the work is based on an existing object. This will be
decided based on the identity property ``__identity``. If this is
not in the input data a new object is created. Otherwise the framework
knows the object identity and can continue working with it.

.. tip::

    When you take a look at what is transferred to the server by the
    new action of the blog example, you will find that no identity
    properties are transferred - in this case a new object is created as
    intended.

In the blog example from above the __identity property is available,
therefore the object with the corresponding UID is fetched from the
repository and used for further modification.

When no properties should be changed the object is given as argument
to the action. So that is always persistent, that is changes to this
object are saved automatically. <remark>!!!Sentence not
clear</remark>

.. figure:: /Images/9-CrosscuttingConcerns/figure-9-3.png
    :align: center

    Figure 9-3: The internal control flow of the property mapper.

In our case not only is the ``__identity`` property sent,
but also a new ``title`` and ``description`` for our
blog. For safety reasons a *copy* of the persistent
object is applied. The properties of the copy are changed as given in the
request, in our case ``title`` and ``description`` are
set new. The generated copy is yet a transient object (see section "live
cycle of objects" in chapter 2), that is changes on the object are
*not* automatically persisted. The changed copy is
given to the action as argument.

Now we have to explicitly tell our controller that we want to
replace the existing persistent ``blog`` object with our modified
``blog`` object. For this, the repository provides the method
update()::

    $this->blogRepository->update($blog);

With this the changed object will be made into the persistent
object: The changes are now permanently stored.

.. sidebar:: Copies of objects

    Why a copy of an object is created when it is to be changed? Lets
    assume that the persistent object would be directly changed. In
    this case an empty controller would be updating persistent
    objects::

        public function updateAction(\MyVendor\BlogExample\Domain\Model\Blog $blog)
        {
            // object will be automatically persisted
        }

    This is not transparent and difficult to understand.
    Besides that, this procedure introduces a big safety issue: When the
    original object is changed it would be impossible to cancel the
    persisting of the changes. For this reason a copy of the object is
    returned for changed objects, so the developer of the extension has to
    decide explicit whether or not the changes are to be made
    persistent.

We want to assume a refinement of the argument mapping: When a link
to an action is generated and the link contains an object as parameter the
identity of the object is transferred automatically. In the following
example the UID is transferred instead of the ``blog``
object::

    <f:link.action action='show' arguments='{blog: blog}'>Show Blog</f:link.action>

The generated URL contains the identity of the blog object:
``tx_blogexample_pi1[blog]=47``. That is a short form of
``tx_blogexample_pi1[blog][__Identity]=47``. Therefore the
property mapper gets the blog object with the identity 47 from the
repository and returns it directly without copying before.

Now that you know about argument mapping in greater detail an can begin to use
it in your own projects.

After you have learned how you can make sure any invariants of
domain objects, the focus will be directed to the secure programming of
the complete extension.