Implement custom field sort clause

lib/API/Values/Content/Query/SortClause/CustomField.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Netgen\EzPlatformSearchExtra\API\Values\Content\Query\SortClause;
+
+use eZ\Publish\API\Repository\Values\Content\Query;
+use eZ\Publish\API\Repository\Values\Content\Query\SortClause;
+use Netgen\EzPlatformSearchExtra\API\Values\Content\Query\Criterion\SubdocumentQuery;
+use Netgen\EzPlatformSearchExtra\API\Values\Content\Query\SortClause\Target\SubdocumentTarget;
+
+/**
+ * CustomField sort clause is used to sort Content by custom field indexed for this content.
+ */
+final class CustomField extends SortClause
+{
+    /**
+     * @param string $fieldName
+     * @param string $sortDirection
+     */
+    public function __construct($fieldName, $sortDirection = Query::SORT_ASC)
+    {
+        parent::__construct($fieldName, $sortDirection);
+    }
+}

lib/Core/Search/Solr/Query/Common/SortClauseVisitor/CustomField.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace Netgen\EzPlatformSearchExtra\Core\Search\Solr\Query\Common\SortClauseVisitor;
+
+use EzSystems\EzPlatformSolrSearchEngine\Query\SortClauseVisitor;
+use eZ\Publish\API\Repository\Values\Content\Query\SortClause;
+use \Netgen\EzPlatformSearchExtra\API\Values\Content\Query\SortClause\CustomField as CustomFieldSortClause;
+
+class CustomField extends SortClauseVisitor
+{
+    /**
+     * Check if visitor is applicable to current sortClause.
+     *
+     * @param SortClause $sortClause
+     *
+     * @return bool
+     */
+    public function canVisit(SortClause $sortClause)
+    {
+        return $sortClause instanceof CustomFieldSortClause;
+    }
+
+    /**
+     * Map field value to a proper Solr representation.
+     *
+     * @param SortClause $sortClause
+     *
+     * @return string
+     */
+    public function visit(SortClause $sortClause)
+    {
+        return $sortClause->target . $this->getDirection($sortClause);
+    }
+}

lib/Resources/config/search/solr/sort_clause_visitors.yml

@@ -17,3 +17,9 @@ services:
         tags:
             - {name: ezpublish.search.solr.query.content.sort_clause_visitor}
             - {name: ezpublish.search.solr.query.location.sort_clause_visitor}
+
+    netgen.search.solr.query.common.sort_clause_visitor.custom_field:
+        class: Netgen\EzPlatformSearchExtra\Core\Search\Solr\Query\Common\SortClauseVisitor\CustomField
+        tags:
+            - {name: ezpublish.search.solr.query.content.sort_clause_visitor}
+            - {name: ezpublish.search.solr.query.location.sort_clause_visitor}