Add support for search templates to the high-level REST client.

Author: jtibshirani

client/rest-high-level/src/main/java/org/elasticsearch/client/RestHighLevelClient.java

@@ -64,6 +64,8 @@
 import org.elasticsearch.plugins.spi.NamedXContentProvider;
 import org.elasticsearch.rest.BytesRestResponse;
 import org.elasticsearch.rest.RestStatus;
+import org.elasticsearch.script.mustache.SearchTemplateRequest;
+import org.elasticsearch.script.mustache.SearchTemplateResponse;
 import org.elasticsearch.search.aggregations.Aggregation;
 import org.elasticsearch.search.aggregations.bucket.adjacency.AdjacencyMatrixAggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.adjacency.ParsedAdjacencyMatrix;
@@ -501,6 +503,32 @@ public final void clearScrollAsync(ClearScrollRequest clearScrollRequest,
                 listener, emptySet(), headers);
     }
 
+    /**
+     * Executes a request using the Search Template API.
+     *
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/search-template.html">Search Template API
+     * on elastic.co</a>.
+     */
+    public final SearchTemplateResponse searchTemplate(SearchTemplateRequest searchTemplateRequest,
+                                                       Header... headers) throws IOException {
+        return performRequestAndParseEntity(searchTemplateRequest, RequestConverters::searchTemplate,
+            SearchTemplateResponse::fromXContent, emptySet(), headers);
+    }
+
+    /**
+     * Asynchronously executes a request using the Search Template API
+     *
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/search-template.html">Search Template API
+     * on elastic.co</a>.
+     */
+    public final void searchTemplateAsync(SearchTemplateRequest searchTemplateRequest,
+                                          ActionListener<SearchTemplateResponse> listener,
+                                          Header... headers) {
+        performRequestAsyncAndParseEntity(searchTemplateRequest, RequestConverters::searchTemplate,
+            SearchTemplateResponse::fromXContent, listener, emptySet(), headers);
+    }
+
+
     /**
      * Executes a request using the Ranking Evaluation API.
      *

client/rest-high-level/src/test/java/org/elasticsearch/client/SearchIT.java

@@ -38,8 +38,11 @@
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.SearchScrollRequest;
 import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.common.xcontent.XContentFactory;
+import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.index.query.MatchQueryBuilder;
 import org.elasticsearch.index.query.ScriptQueryBuilder;
 import org.elasticsearch.index.query.TermsQueryBuilder;
@@ -48,6 +51,8 @@
 import org.elasticsearch.rest.RestStatus;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptType;
+import org.elasticsearch.script.mustache.SearchTemplateRequest;
+import org.elasticsearch.script.mustache.SearchTemplateResponse;
 import org.elasticsearch.search.SearchHit;
 import org.elasticsearch.search.aggregations.BucketOrder;
 import org.elasticsearch.search.aggregations.bucket.range.Range;
@@ -69,10 +74,12 @@
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 import static org.elasticsearch.common.xcontent.XContentFactory.jsonBuilder;
+import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertToXContentEquivalent;
 import static org.hamcrest.Matchers.both;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.either;
@@ -733,6 +740,103 @@ public void testMultiSearch_failure() throws Exception {
         assertThat(multiSearchResponse.getResponses()[1].getResponse(), nullValue());
     }
 
+    public void testSearchTemplate() throws IOException {
+        SearchTemplateRequest searchTemplateRequest = new SearchTemplateRequest();
+        searchTemplateRequest.setRequest(new SearchRequest("index"));
+
+        searchTemplateRequest.setScriptType(ScriptType.INLINE);
+        searchTemplateRequest.setScript(
+            "{" +
+            "  \"query\": {" +
+            "    \"match\": {" +
+            "      \"num\": {{number}}" +
+            "    }" +
+            "  }" +
+            "}");
+
+        Map<String, Object> scriptParams = new HashMap<>();
+        scriptParams.put("number", 10);
+        searchTemplateRequest.setScriptParams(scriptParams);
+
+        searchTemplateRequest.setExplain(true);
+        searchTemplateRequest.setProfile(true);
+
+        SearchTemplateResponse searchTemplateResponse = execute(searchTemplateRequest,
+            highLevelClient()::searchTemplate,
+            highLevelClient()::searchTemplateAsync);
+
+        assertNull(searchTemplateResponse.getSource());
+
+        SearchResponse searchResponse = searchTemplateResponse.getResponse();
+        assertNotNull(searchResponse);
+
+        assertEquals(1, searchResponse.getHits().totalHits);
+        assertEquals(1, searchResponse.getHits().getHits().length);
+        assertThat(searchResponse.getHits().getMaxScore(), greaterThan(0f));
+
+        SearchHit hit = searchResponse.getHits().getHits()[0];
+        assertNotNull(hit.getExplanation());
+
+        assertFalse(searchResponse.getProfileResults().isEmpty());
+    }
+
+    public void testNonExistentSearchTemplate() {
+        SearchTemplateRequest searchTemplateRequest = new SearchTemplateRequest();
+        searchTemplateRequest.setRequest(new SearchRequest("index"));
+
+        searchTemplateRequest.setScriptType(ScriptType.STORED);
+        searchTemplateRequest.setScript("non-existent");
+        searchTemplateRequest.setScriptParams(Collections.emptyMap());
+
+        ElasticsearchStatusException exception = expectThrows(ElasticsearchStatusException.class,
+            () -> execute(searchTemplateRequest,
+                highLevelClient()::searchTemplate,
+                highLevelClient()::searchTemplateAsync));
+
+        assertEquals(RestStatus.NOT_FOUND, exception.status());
+    }
+
+    public void testRenderSearchTemplate() throws IOException {
+        SearchTemplateRequest searchTemplateRequest = new SearchTemplateRequest();
+
+        searchTemplateRequest.setScriptType(ScriptType.INLINE);
+        searchTemplateRequest.setScript(
+            "{" +
+            "  \"query\": {" +
+            "    \"match\": {" +
+            "      \"num\": {{number}}" +
+            "    }" +
+            "  }" +
+            "}");
+
+        Map<String, Object> scriptParams = new HashMap<>();
+        scriptParams.put("number", 10);
+        searchTemplateRequest.setScriptParams(scriptParams);
+
+        // Setting simulate true causes the template to only be rendered.
+        searchTemplateRequest.setSimulate(true);
+
+        SearchTemplateResponse searchTemplateResponse = execute(searchTemplateRequest,
+            highLevelClient()::searchTemplate,
+            highLevelClient()::searchTemplateAsync);
+        assertNull(searchTemplateResponse.getResponse());
+
+        BytesReference expectedSource = BytesReference.bytes(
+            XContentFactory.jsonBuilder()
+                .startObject()
+                    .startObject("query")
+                        .startObject("match")
+                            .field("num", 10)
+                        .endObject()
+                    .endObject()
+                .endObject());
+
+        BytesReference actualSource = searchTemplateResponse.getSource();
+        assertNotNull(actualSource);
+
+        assertToXContentEquivalent(expectedSource, actualSource, XContentType.JSON);
+    }
+
     public void testFieldCaps() throws IOException {
         FieldCapabilitiesRequest request = new FieldCapabilitiesRequest()
             .indices("index1", "index2")