GraphQL - Added sort by options to Products GraphQL type

app/code/Magento/CatalogGraphQl/Model/Resolver/Category/SortFields.php

@@ -0,0 +1,82 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\CatalogGraphQl\Model\Resolver\Category;
+
+use Magento\Framework\GraphQl\Schema\Type\ResolveInfo;
+use Magento\Framework\GraphQl\Config\Element\Field;
+use Magento\Framework\GraphQl\Query\Resolver\Value;
+use Magento\Framework\GraphQl\Query\Resolver\ValueFactory;
+use Magento\Framework\GraphQl\Query\ResolverInterface;
+
+/**
+ * Retrieves the sort fields data
+ */
+class SortFields implements ResolverInterface
+{
+    /**
+     * @var ValueFactory
+     */
+    private $valueFactory;
+
+    /**
+     * @var \Magento\Catalog\Model\Config
+     */
+    private $catalogConfig;
+
+    /**
+     * @var \Magento\Store\Model\StoreManagerInterface
+     */
+    private $storeManager;
+
+    /**
+     * @var \Magento\Catalog\Model\Category\Attribute\Source\Sortby
+     */
+    private $sortbyAttributeSource;
+
+    /**
+     * @param ValueFactory $valueFactory
+     * @param \Magento\Catalog\Model\Config $catalogConfig
+     * @param \Magento\Store\Model\StoreManagerInterface $storeManager
+     * @oaram \Magento\Catalog\Model\Category\Attribute\Source\Sortby $sortbyAttributeSource
+     */
+    public function __construct(
+        ValueFactory $valueFactory,
+        \Magento\Catalog\Model\Config $catalogConfig,
+        \Magento\Store\Model\StoreManagerInterface $storeManager,
+        \Magento\Catalog\Model\Category\Attribute\Source\Sortby $sortbyAttributeSource
+    ) {
+        $this->valueFactory = $valueFactory;
+        $this->catalogConfig = $catalogConfig;
+        $this->storeManager = $storeManager;
+        $this->sortbyAttributeSource = $sortbyAttributeSource;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function resolve(Field $field, $context, ResolveInfo $info, array $value = null, array $args = null) : Value
+    {
+        $sortFieldsOptions = $this->sortbyAttributeSource->getAllOptions();
+        array_walk(
+            $sortFieldsOptions,
+            function (&$option) {
+                $option['label'] = (string)$option['label'];
+            }
+        );
+        $data = [
+            'default' => $this->catalogConfig->getProductListDefaultSortBy($this->storeManager->getStore()->getId()),
+            'options' => $sortFieldsOptions,
+        ];
+
+        $result = function () use ($data) {
+            return $data;
+        };
+
+        return $this->valueFactory->create($result);
+    }
+}

app/code/Magento/CatalogGraphQl/Model/Resolver/Products.php

@@ -123,9 +123,10 @@ public function resolve(
             'items' => $searchResult->getProductsSearchResult(),
             'page_info' => [
                 'page_size' => $searchCriteria->getPageSize(),
-                'current_page' => $currentPage
+                'current_page' => $currentPage,
+                'sort_fields' => [],
             ],
-            'filters' => $this->filtersDataProvider->getData($layerType)
+            'filters' => $this->filtersDataProvider->getData($layerType),
         ];
 
         $result = function () use ($data) {

app/code/Magento/CatalogGraphQl/etc/schema.graphqls

@@ -402,6 +402,7 @@ type Products @doc(description: "The Products object is the top-level object ret
     page_info: SearchResultPageInfo @doc(description: "An object that includes the page_info and currentPage values specified in the query")
     total_count: Int @doc(description: "The number of products returned")
     filters: [LayerFilter] @doc(description: "Layered navigation filters array")
+    sort_fields: SortFields @doc(description: "An object that includes the default sort field and all available sort fields") @resolver(class: "Magento\\CatalogGraphQl\\Model\\Resolver\\Category\\SortFields")
 }
 
 input ProductFilterInput @doc(description: "ProductFilterInput defines the filters to be used in the search. A filter contains at least one attribute, a comparison operator, and the value that is being searched for.") {
@@ -521,3 +522,13 @@ interface LayerFilterItemInterface @typeResolver(class: "Magento\\CatalogGraphQl
 type LayerFilterItem implements LayerFilterItemInterface {
 
 }
+
+type SortField {
+    value: String @doc(description: "Attribute code of sort field")
+    label: String @doc(description: "Label of sort field")
+}
+
+type SortFields @doc(description: "SortFields contains a default value for sort fields and all available sort fields") {
+    default: String @doc(description: "Default value of sort fields") 
+    options: [SortField] @doc(description: "Available sort fields")
+}

app/code/Magento/GraphQl/etc/schema.graphqls

@@ -30,4 +30,4 @@ type SearchResultPageInfo @doc(description: "SearchResultPageInfo provides navig
 enum SortEnum @doc(description: "This enumeration indicates whether to return results in ascending or descending order") {
     ASC
     DESC
-}
+}

dev/tests/api-functional/testsuite/Magento/GraphQl/Catalog/ProductSearchTest.php

@@ -512,6 +512,15 @@ public function testQueryProductsInCurrentPageSortedByPriceASC()
           page_size
           current_page
         }
+        sort_fields 
+        {
+          default
+          options 
+          {
+            value
+            label
+          }
+        }
     }
 }
 QUERY;
@@ -530,6 +539,13 @@ public function testQueryProductsInCurrentPageSortedByPriceASC()
         $this->assertProductItems($filteredChildProducts, $response);
         $this->assertEquals(4, $response['products']['page_info']['page_size']);
         $this->assertEquals(1, $response['products']['page_info']['current_page']);
+        $this->assertArrayHasKey('sort_fields', $response['products']);
+        $this->assertArrayHasKey('options', $response['products']['sort_fields']);
+        $this->assertArrayHasKey('default', $response['products']['sort_fields']);
+        $this->assertEquals('position', $response['products']['sort_fields']['default']);
+        $this->assertArrayHasKey('value', $response['products']['sort_fields']['options'][0]);
+        $this->assertArrayHasKey('label', $response['products']['sort_fields']['options'][0]);
+        $this->assertEquals('position', $response['products']['sort_fields']['options'][0]['value']);
     }
 
     /**