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Displaying children of a Content item

Description

One of the basic design tasks you may need to complete when creating your website is configuring one page to display all of its children. Examples are having a blog display blog posts, of a folder that shows all articles it contains.

Solution

There are two ways to make a Content item display its children:

  1. Using a Custom Controller
  2. Using the Query Controller

This recipe will show how to use both those methods to display all children of a Content item with the Content Type Folder.

Using a Custom Controller

There are three different ways of using a Custom Controller that you can learn about in the Custom Controller page. In this case we will be applying the first of these, that is using the Custom Controller alongside the built-in ViewController.

Configuring for the use of a Custom Controller starts with pointing to it in your standard view configuration (which you can keep in ezplatform.yml or a separate file, for example views.yml):

folder:
    controller: app.controller.folder:showAction
    template: "full/folder.html.twig"
    match:
        Identifier\ContentType: "folder"

Besides the standard view config, under the controller key you need to provide here the path to the Controller and the action. They are defined in the following file:

// AppBundle/Controller/FolderController.php
<?php

namespace AppBundle\Controller;

use eZ\Publish\API\Repository\ContentService;
use eZ\Publish\API\Repository\LocationService;
use eZ\Publish\API\Repository\SearchService;
use eZ\Publish\API\Repository\Values\Content\Query;
use eZ\Publish\API\Repository\Values\Content\Query\SortClause;
use eZ\Publish\Core\MVC\ConfigResolverInterface;
use eZ\Publish\Core\MVC\Symfony\View\ContentView;
use AppBundle\Criteria\Children;

class FolderController {

    /** @var \eZ\Publish\API\Repository\SearchService */
    protected $searchService;

    /** @var \eZ\Publish\Core\MVC\ConfigResolverInterface */
    protected $configResolver;

    /** @var \AppBundle\Criteria\Children */
    protected $childrenCriteria;

    /**
     * @param \eZ\Publish\API\Repository\SearchService $searchService
     * @param \eZ\Publish\Core\MVC\ConfigResolverInterface $configResolver
     * @param \AppBundle\Criteria\Children $childrenCriteria
     */
    public function __construct(
        SearchService $searchService,
        ConfigResolverInterface $configResolver,
        Children $childrenCriteria
    ) {
        $this->searchService = $searchService;
        $this->configResolver = $configResolver;
        $this->childrenCriteria = $childrenCriteria;
    }

    /**
     * Displays blog posts and gallery images on home page.
     *
     * @param \eZ\Publish\Core\MVC\Symfony\View\ContentView $view
     *
     * @return \eZ\Publish\Core\MVC\Symfony\View\ContentView
     */
    public function showAction(ContentView $view)
    {
        $view->addParameters([
            //'content' => $this->contentService->loadContentByContentInfo($view->getLocation()->getContentInfo()),
            'items' => $this->fetchItems($view->getLocation(), 25),
        ]);
        return $view;
    }

    private function fetchItems($location, $limit)
    {
        $languages = $this->configResolver->getParameter('languages');
        $query = new Query();
        //$location = $this->locationService->loadLocation($locationId);

    $query->query = $this->childrenCriteria->generateChildCriterion($location, $languages);
        $query->performCount = false;
        $query->limit = $limit;
        $query->sortClauses = [
            new SortClause\DatePublished(Query::SORT_DESC),
        ];
        $results = $this->searchService->findContent($query);
        $items = [];
        foreach ($results->searchHits as $item) {
            $items[] = $item->valueObject;
        }
        return $items;
    }

}

As you can see, this Controller makes use of the generateChildCriterion, which means you need to provide a file containing this function:

// AppBundle/Criteria/Children.php
<?php

namespace AppBundle\Criteria;

use eZ\Publish\API\Repository\Values\Content\Location;
use eZ\Publish\API\Repository\Values\Content\Query\Criterion;

class Children
{
    /**
     * Generate criterion list to be used to fetch sub-items.
     *
     * @param \eZ\Publish\API\Repository\Values\Content\Location $location location of the root
     * @param string[] $languages array of languages
     *
     * @return \eZ\Publish\API\Repository\Values\Content\Query\Criterion
     */
    public function generateChildCriterion(Location $location, array $languages = [])
    {
        return new Criterion\LogicalAnd([
            new Criterion\Visibility(Criterion\Visibility::VISIBLE),
            new Criterion\ParentLocationId($location->id),
            new Criterion\Subtree($location->pathString),
            new Criterion\LanguageCode($languages),
        ]);
    }
}

Next, you must register these two services:

# AppBundle/Resources/config/services.yml
services:

    app.criteria.children:
        class: AppBundle\Criteria\Children

    app.controller.folder:
        class: AppBundle\Controller\FolderController
        arguments:
            - '@ezpublish.api.service.search'
            - '@ezpublish.config.resolver'
            - '@app.criteria.children'

Finally, let's use the Controller in a template:

<!--app/Resources/views/full/folder.html.twig-->
<h1>{{ ez_content_name(content) }}</h1>

{% for item in items %}
  <h2>{{ ez_content_name(item) }}</h2>
{% endfor %}

This template makes use of the items specified in the Controller file to list every child of the folder.

Using the Query Controller

The Query Controller is a predefined custom content view Controller that runs a Repository Query.

If you need to create a simple query it's easier to use the Query Controller than to build a completely custom one, as you will not have to write custom PHP code. Like with a Custom Controller, however, you will be able to use properties of the viewed Content or Location as parameters.

The main file in this case is a LocationChildrenQueryType.php file which generates a Query that retrieves the children of the current Location.

// AppBundle/QueryType/LocationChildrenQueryType.php
<?php
namespace AppBundle\QueryType;

use eZ\Publish\API\Repository\Values\Content\LocationQuery;
use eZ\Publish\API\Repository\Values\Content\Query\Criterion\ParentLocationId;
use eZ\Publish\Core\QueryType\QueryType;

class LocationChildrenQueryType implements QueryType
{
    public function getQuery(array $parameters = [])
    {
        return new LocationQuery([
            'filter' => new ParentLocationId($parameters['parentLocationId']),
        ]);
    }

    public function getSupportedParameters()
    {
        return ['parentLocationId'];
    }
//
    public static function getName()
    //
        return 'LocationChildren';
    }
}

Next, in your standard view configuration file include a block that indicates when this Controller will be used. It is similar to regular view config, but contains additional information:

folder:
    controller: "ez_query:locationQueryAction"
    template: "full/folder.html.twig"
    match:
        Identifier\ContentType: "folder"
    params:
        query:
            query_type: 'LocationChildren'
            parameters:
                parentLocationId: "@=location.id"
            assign_results_to: 'items'

In this case the controller key points to the Query Controller's locationQuery action. assign_results_to identifies the parameter containing all the retrieved children that will later be used in the templates:

<!--app/Resources/views/full/folder.html.twig-->
<h1>{{ ez_content_name(content) }}</h1>

{% for item in items.searchHits %}
  <h2>{{ ez_content_name(item.valueObject.contentInfo) }}</h2>
{% endfor %}

This template makes use of the items specified in assign_results_to to list every child of the folder.

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