View Model

About MVC Interactions

In most MVC practices, there is no direct communication between View and Model. We called it Passive View. But there are many variants of MVC like: MVVM, MVP etc.

Windwalker uses a pattern which is similar to Supervising Controller, MVVM or MVP , View can not communicate to Model or Repository, but Controller can binding Repository to View, then View is able to get data from Repository.

The benefit of this pattern is that View can decide what data is necessary for this page or layout and call Repository to get data. And controller's responsibility is just binding repositories to view. There is a ViewModel between View and Repository to handle request from View and get data from Repository.

Schematic Diagram

ViewModel

View is not directly communicate to Repository, there is a ViewModel object between them. You can consider ViewModel as a Repository manager.

Use ViewModel Pattern in Windwalker

This is a traditional MVC usage in controller:

// doExecute()

$repo = new FlowerRepository();
$view = new SakurasHtmlView();

$item = $repo->getItem();

$view['created'] = $item;

return $view->render();

Change some code, we can push Repository into View:

// doExecute()

$repo = new FlowerRepository();
$view = new SakurasHtmlView();

$view->setRepository($repo);

// Or set with prepare repo state
$view->setRepository($repository, function (FlowerRepository $repo)
{
    $repo->set('item.id', $this->input->get('id'));
});

return $view->render();

Get data in View:

class SakurasHtmlView extends HtmlView
{
    protected function prepareData($data)
    {
        $data->item = $this->repository->getItem();
    }
}

The $view->repository property is ViewModel object, if we call any method, ViewModel will pass this method to default Model by magic method. If Repository does not have this method, it will only return null.

We can also get data by pipe() or applyData() with a callback and class hint:

// In View

protected function prepareData($data)
{
    // Use pipe()
    $this->pipe(function (FlowerRepository $repo, $view) use ($data)
    {
        $data->item = $repo->getItem();
    });

    // Use applyData
    $this->applyData(function (FlowerRepository $repository, $data)
    {
        $data->item = $repository->getItem();
    });

    // ...

You must make sure Repository named with XXXRepository, the Repository will guess their own name. you can also set name property when declaring Repository class. There is some ways to define Repository's name:

// Set by config
$repository->config->set('name', 'foo');

// Use class name
class FooRepository extends Repository {}

// Use property
class SomeRepository extends Repository
{
    protected $name = 'foo';
}

Set Multiple Repositories

We can get many repositories and push them into one view.

// In Controller::doExecute()

$repository = $this->getRepository();
$roseRepo = $this->getRepository('Rose');
$oliveRepo = $this->getRepository('Olive');

$view->setRepository($repository, true); // Second argument TRUE as default
$view->setRepository($roseRepo);
$view->setRepository($oliveRepo [, custom name]);

return $view->render();

Set sub models with custom name alias:

$view->setRepository($repository, true); // Second argument TRUE as default
$view->addRepository('rose', $roseRepo);
$view->addRepository('olive', $oliveRepo);

If you want to set state when setting repositories, use callback:

$view->addRepository('rose', $this->getRepository('Rose'), function (RoseRepository $repository) {
    $repository->set('list.page', 5);
});

Use configureRepository() or pipe() to configure models after set in View:

$view->configureRepository('rose', function (RoseRepository $repository, $view) {
    $repository->set('list.limit', 15);
});

// pipe() will return value:
$list = $view->pipe('rose', function (RoseRepository $repository, $view) {
    $repository->set('list.limit', 15);
    return $repository->getList();
});

Get Sub Repositories in View

Use array access to get different repositories and call methods in View.

// In View::prepareData()

$data->items = $this->repository->getItems();
$data->roses = $this->repository['rose']->getRoses();
$data->olives = $this->repository['olive']->getOlives();

If a model not set, and the method name start with get* or load*, it will return null.

$data->foo = $this->repository['foo']->getFoo();

You can also use $this->pipe() or $this->applyData(), remember send string as first argument to find repository by name alias.

// In view

protected function prepareData($data)
{
    $this->applyData('rose', function (RoseRepository $repository, Data $data) {
        $data->roses = $repository->getList();
    });

    // Inject dat to cllback
    $this->pipe('rose', function (RoseRepository $repository, $view) use ($data) {
        $data->roses = $repository->getList();
    });

    // Or just return value
    $data->roses = $this->pipe('rose', function (RoseRepository $repository, $view) {
        return $repository->getList();
    });

    // ...

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