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Displaying Content item children

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. For example you can configure a blog displaying all blog posts or a folder showing all articles it contains.

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

1. Using the Query Controller
2. Using the Content query Field Type
3. Using a Custom Controller

This procedure demonstrates how to use these three methods to display all children of a Content item with the Content Type Folder.

Using the Query Controller

The Query Controller is a pre-defined custom content view Controller that runs a Repository Query.

If you need to create a simple Query, it is 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 an AppBundle/QueryType/LocationChildrenQueryType.php file which generates a Query that retrieves the children of the current Location.

<?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, under content_view, add a section 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, like here in app/Resources/views/full/folder.html.twig:

<h1>{{ ez_content_name(content) }}</h1>

{% for item in items.searchHits %}
  <h2><a href={{ path('ez_urlalias', {'contentId': item.valueObject.contentInfo.id}) }}>{{ ez_content_name(item.valueObject.contentInfo) }}</a></h2>
{% endfor %}

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

Using the Content query Field Type

You can also use the same Query Type as above together with the Content query Field Type.

The Content query Field Type is available via the eZ Platform Query Field Type Bundle provided by the ezplatform-query-fieldtype package. You need to add the package manually to your project.

To use the Query Type with a Content query Field, add the Field to your Folder Content Type's definition.

Select "Location children" as the Query type. Provide the parentLocationId parameter that the Query type requires:

parentLocationId: '@=mainLocation.id'

You can paginate the query results by checking the Enable pagination box and selecting a limit of results per page.

To customize the display template, in your standard view configuration file, under content_view, add a section that indicates the matcher and template to use:

content_query_field:
    folder_children:
        match:
            Identifier\ContentType: folder
            Identifier\FieldDefinition: children
        template: content_query/folder.html.twig

Then, provide the template in app/Resources/views/content_query/folder.html.twig. The query results are available in the items variable:

<h1>{{ ez_content_name(content) }}</h1>

{% for item in items %}
    <h2><a href={{ path('ez_urlalias', {'contentId': item.contentInfo.id}) }}>{{ ez_content_name(item.contentInfo) }}</a></h2>
{% endfor %}

{% if isPaginationEnabled %}
    {{ pagerfanta( items, 'ez', {'routeName': location, 'pageParameter': pageParameter } ) }}
{% endif %}

Using a Custom Controller

There are three different ways of using a Custom Controller. For details, see Custom Controller section.

In this case we will be 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 as a separate file, for example views.yml):

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

You can see here the standard view config consisting of the template and match keys. Under the controller key, you need to provide here the path to the Controller and the action. They are defined in 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([
            'items' => $this->fetchItems($view->getLocation(), 25),
        ]);
        return $view;
    }

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

        $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 an AppBundle/Criteria/Children.php file containing this function:

<?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 in 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'

The next step is to create an AppBundle/DependencyInjection/AppExtension.php file to load service configuration:

<?php

namespace AppBundle\DependencyInjection;

use Symfony\Component\HttpKernel\DependencyInjection\Extension;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Loader\YamlFileLoader;
use Symfony\Component\Config\FileLocator;

class AppExtension extends Extension
{
    public function load(array $configs, ContainerBuilder $container)
    {
        $loader = new YamlFileLoader(
            $container,
            new FileLocator(__DIR__ . '/../Resources/config')
        );
        $loader->load('services.yml');
    }
}

Finally, let's use the Controller in a app/Resources/views/full/folder.html.twig template:

<h1>{{ ez_content_name(content) }}</h1>

{% for item in items %}
  <h2><a href={{ path('ez_urlalias', {'contentId': item.contentInfo.id}) }}>{{ ez_content_name(item) }}</a></h2>
{% endfor %}

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