Register a custom DataProvider to filter pages by their template

The smart_content content type allows for the configuration of a provider param, which is used for gathering the items that are passed to the twig template. As described in Smart content, Sulu comes with a few included providers and also allows to implement new ones to load custom entities.

In some cases, it might be useful to register an additional provider for pages that only returns pages that use a specific template or include a property with a specific value. This is possible by registering a new instance of the PageDataProvider included in Sulu that uses a custom QueryBuilder implementation. To do this, the following changes are required:

1. Implement a custom ``QueryBuilder`` class that adds conditions

// src/SmartContent/ProductPageQueryBuilder.php

namespace App\SmartContent;

use Sulu\Component\Content\SmartContent\QueryBuilder;

class ProductPageQueryBuilder extends QueryBuilder
    protected function buildWhere($webspaceKey, $locale)
        // reuse existing functionality of the default QueryBuilder implementation
        $sql2Where = explode(' AND ', parent::buildWhere($webspaceKey, $locale));

        // add custom condition to check the template of the page to the query
        $sql2Where[] = "(page.[i18n:" . $locale . "-template] = 'product')";

        // optional: add custom condition to check the value of a specific property of the page to the query
        // $sql2Where[] = "(page.[i18n:" . $locale . "-propertyName] = 'propertyValue')";

        return implode(' AND ', $sql2Where);

2. Register ``PageDataProvider` service that uses custom ``QueryBuilder`` implementation

# config/services.yaml
        class: App\SmartContent\ProductPageQueryBuilder
            - '@sulu.content.structure_manager'
            - '@sulu_page.extension.manager'
            - '@sulu.phpcr.session'
            - '%sulu.content.language.namespace%'
        class: Sulu\Component\Content\SmartContent\PageDataProvider
            - '@app.smart_content.product_page_query_builder'
            - '@sulu.content.query_executor'
            - '@sulu_document_manager.document_manager'
            - '@sulu_page.smart_content.data_provider.content.proxy_factory'
            - '@sulu_document_manager.default_session'
            - '@sulu_page.reference_store.content'
            - '%sulu_document_manager.show_drafts%'
            - { name: 'sulu.smart_content.data_provider', alias: 'product_pages'}

3. Use registered ``product_pages`` DataProvider in the template

<property name="productPages" type="smart_content">
        <title lang="en">Product Pages</title>

        <param name="provider" value="product_pages"/>