FEATURE: More like this

This implements an convinent API to build more like this queries.
For details see [Elasticsearch documentation](https://www.elastic.co/guide/en/elasticsearch/reference/5.6/query-dsl-mlt-query.html)

Author: daniellienert

Classes/Driver/AbstractQuery.php

@@ -109,6 +109,22 @@ public function aggregation($name, array $aggregationDefinition, $parentPath = '
         }
     }
 
+    /**
+     * {@inheritdoc}
+     * @throws Exception\QueryBuildingException
+     */
+    public function moreLikeThis(array $like, array $fields = [], $options = [])
+    {
+        $moreLikeThis = $options;
+        $moreLikeThis['like'] = $like;
+
+        if (!empty($fields)) {
+            $moreLikeThis['fields'] = $fields;
+        }
+        
+        $this->appendAtPath('query.bool.filter.bool.must', ['more_like_this' => $moreLikeThis]);
+    }
+
     /**
      * This is an low level method for internal usage.
      *
@@ -119,7 +135,6 @@ public function aggregation($name, array $aggregationDefinition, $parentPath = '
      * @param string $parentPath The parent path to add the sub aggregation to
      * @param string $name The name to identify the resulting aggregation
      * @param array $aggregationConfiguration
-     * @return QueryInterface
      * @throws Exception\QueryBuildingException
      */
     protected function addSubAggregation($parentPath, $name, $aggregationConfiguration)

Classes/Driver/QueryInterface.php

@@ -111,6 +111,18 @@ public function aggregation($name, array $aggregationDefinition, $parentPath = '
      */
     public function suggestions($name, array $suggestionDefinition);
 
+    /**
+     * This method is used to define a more like this query.
+     * The More Like This Query (MLT Query) finds documents that are "like" a given text
+     * or a given set of documents
+     *
+     * @param array $like An array of strings or documents
+     * @param array $fields Fields to compare other docs with
+     * @param array $options Additional options for the more_like_this quey
+     * @return void
+     */
+    public function moreLikeThis(array $like, array $fields = [], array $options = []);
+
     /**
      * Add a query filter
      *

Classes/Eel/ElasticSearchQueryBuilder.php

@@ -11,6 +11,7 @@
  * source code.
  */
 
+use Neos\Flow\Annotations as Flow;
 use Flowpack\ElasticSearch\ContentRepositoryAdaptor\Driver\QueryInterface;
 use Flowpack\ElasticSearch\ContentRepositoryAdaptor\Dto\SearchResult;
 use Flowpack\ElasticSearch\ContentRepositoryAdaptor\ElasticSearchClient;
@@ -21,7 +22,6 @@
 use Neos\ContentRepository\Domain\Model\NodeInterface;
 use Neos\ContentRepository\Search\Search\QueryBuilderInterface;
 use Neos\Eel\ProtectedContextAwareInterface;
-use Neos\Flow\Annotations as Flow;
 use Neos\Flow\ObjectManagement\ObjectManagerInterface;
 use Neos\Flow\Utility\Now;
 use Neos\Utility\Arrays;
@@ -567,6 +567,7 @@ public function fetch()
         try {
             $timeBefore = microtime(true);
             $request = $this->request->getRequestAsJson();
+
             $response = $this->elasticSearchClient->getIndex()->request('GET', '/_search', [], $request);
             $timeAfterwards = microtime(true);
 
@@ -670,6 +671,48 @@ public function highlight($fragmentSize, $fragmentCount = null)
         return $this;
     }
 
+    /**
+     * This method is used to define a more like this query.
+     * The More Like This Query (MLT Query) finds documents that are "like" a given set of documents.
+     * See: https://www.elastic.co/guide/en/elasticsearch/reference/5.6/query-dsl-mlt-query.html
+     *
+     * @param array $like An array of strings or documents
+     * @param array $fields Fields to compare other docs with
+     * @param array $options Additional options for the more_like_this quey
+     * @return ElasticSearchQueryBuilder
+     */
+    public function moreLikeThis($like, array $fields = [], array $options = [])
+    {
+        $like = is_array($like) ? $like : [$like];
+
+        $getDocumentDefinitionByNode = function (QueryInterface $request, NodeInterface $node): array {
+            $request->queryFilter('term', ['__identifier' => $node->getIdentifier()]);
+            $response = $this->elasticSearchClient->getIndex()->request('GET', '/_search', [], $request->toArray())->getTreatedContent();
+
+            $respondedDocuments = Arrays::getValueByPath($response, 'hits.hits');
+            if (count($respondedDocuments) === 0) {
+                throw new Exception(sprintf('The node with identifier %s was not found in the elasticsearch index', $node->getIdentifier()), 1536485615);
+            }
+            $respondedDocument = current($respondedDocuments);
+            return [
+                '_id' => $respondedDocument['_id'],
+                '_type' => $respondedDocument['_type'],
+                '_index' => $respondedDocument['_index'],
+            ];
+        };
+
+        foreach ($like as $key => $likeElement) {
+            if ($likeElement instanceof NodeInterface) {
+                $like[$key] = $getDocumentDefinitionByNode(clone $this->request, $likeElement);
+            }
+        }
+
+        $this->request->moreLikeThis($like, $fields, $options);
+
+        return $this;
+    }
+
+
     /**
      * Sets the starting point for this query. Search result should only contain nodes that
      * match the context of the given node and have it as parent node in their rootline.

README.md

@@ -133,6 +133,14 @@ Furthermore, the following operators are supported:
 * `from(5)` -- return the results starting from the 6th one
 * `fulltext('searchWord', options)` -- do a query_string query on the Fulltext index using the searchword and additional [options](https://www.elastic.co/guide/en/elasticsearch/reference/5.6/query-dsl-query-string-query.html) to the query_string
 
+#### moreLikeThis(like, fields, options)
+
+The More Like This Query (MLT Query) finds documents that are "like" a given text or a given set of documents.
+
+* `like` Single value or an array of strings or nodes.
+* `fields` An array of fields which are used to compare other docs with the given "like" definition.
+* `options` Additional options for the `more_like_this` query. See the [elasticsearch documentation](https://www.elastic.co/guide/en/elasticsearch/reference/5.6/query-dsl-mlt-query.html) for what is possible.
+
 Furthermore, there is a more low-level operator which can be used to add arbitrary Elasticsearch filters:
 
 * `queryFilter("filterType", {option1: "value1"}, [clauseType])`