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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 Content query Field Type
2. Using the Query Controller
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 Content query Field Type

The Query Controller is a pre-defined custom content view Controller that runs a Repository Query that you can use together with the Content query Field Type.

This example uses the built-in Children Query Type which retrieves the children of the current Location.

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

Select "Children" as the Query Type. Provide the content parameter that the Query type requires:

content: '@=content'

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
            '@EzSystems\EzPlatformQueryFieldType\eZ\ContentView\FieldDefinitionIdentifierMatcher': children
        template: content_query/folder.html.twig

Then, provide the template in templates/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={{ ez_path(item) }}>{{ ez_content_name(item.contentInfo) }}</a></h2>
{% endfor %}

{% if isPaginationEnabled %}
    {{ pagerfanta( items, 'ez', {
        'pageParameter': pageParameter,
        'routeName': '_ez_content_view',
        'routeParams' : {'contentId': content.id, 'locationId': location.id }
    } ) }}
{% endif %}

Using the Query Controller

You can also use the Children Query Type together with the Query Controller.

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::contentQueryAction
    template: full/folder.html.twig
    match:
        Identifier\ContentType: folder
    params:
        query:
            query_type: Children
            parameters:
                location: '@=location'
            assign_results_to: items

In this case the controller key points to the Query Controller's contentQuery action. assign_results_to identifies the parameter containing all the retrieved children that will later be used in the templates, like here in templates/full/folder.html.twig:

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

{% for item in items.searchHits %}
  <h2><a href={{ ez_path(item.valueObject) }}>{{ 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 a Custom Controller

There are three different ways of using a Custom Controller. 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.yaml or as a separate file, for example views.yaml):

folder:
    controller: App\Controller\FolderController::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 the path to the Controller and the action. They are defined in src/Controller/FolderController.php:

<?php

namespace App\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 App\Criteria\Children;

class FolderController
{

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

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

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

    /**
     * @param \eZ\Publish\API\Repository\SearchService $searchService
     * @param \eZ\Publish\Core\MVC\ConfigResolverInterface $configResolver
     * @param \App\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 src/Criteria/Children.php file containing this function:

<?php

namespace App\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 config/services.yaml:

services:
    app.criteria.children:
        class: App\Criteria\Children

    App\Controller\FolderController:
        class: App\Controller\FolderController
        arguments:
            - '@ezpublish.api.service.search'
            - '@ezpublish.config.resolver'
            - '@app.criteria.children'
        tags:
            - { name: controller.service_arguments }

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

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

{% for item in items %}
  <h2><a href={{ ez_path(item.valueObject) }}>{{ 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.