Backport: Add Get Source API to the HLRC

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

@@ -49,6 +49,7 @@
 import org.elasticsearch.action.support.WriteRequest;
 import org.elasticsearch.action.update.UpdateRequest;
 import org.elasticsearch.client.core.CountRequest;
+import org.elasticsearch.client.core.GetSourceRequest;
 import org.elasticsearch.client.core.MultiTermVectorsRequest;
 import org.elasticsearch.client.core.TermVectorsRequest;
 import org.elasticsearch.client.indices.AnalyzeRequest;
@@ -281,6 +282,14 @@ private static Request getStyleRequest(String method, GetRequest getRequest) {
     }
 
     static Request sourceExists(GetRequest getRequest) {
+        Params parameters = new Params();
+        parameters.withPreference(getRequest.preference());
+        parameters.withRouting(getRequest.routing());
+        parameters.withRefresh(getRequest.refresh());
+        parameters.withRealtime(getRequest.realtime());
+        parameters.withFetchSourceContext(getRequest.fetchSourceContext());
+        // Version params are not currently supported by the _source API so are not passed
+
         String optionalType = getRequest.type();
         String endpoint;
         if (optionalType.equals(MapperService.SINGLE_MAPPING_NAME)) {
@@ -289,12 +298,20 @@ static Request sourceExists(GetRequest getRequest) {
             endpoint = endpoint(getRequest.index(), optionalType, getRequest.id(), "_source");
         }
         Request request = new Request(HttpHead.METHOD_NAME, endpoint);
+        request.addParameters(parameters.asMap());
+        return request;
+    }
+
+    static Request getSource(GetSourceRequest getSourceRequest) {
         Params parameters = new Params();
-        parameters.withPreference(getRequest.preference());
-        parameters.withRouting(getRequest.routing());
-        parameters.withRefresh(getRequest.refresh());
-        parameters.withRealtime(getRequest.realtime());
-        // Version params are not currently supported by the source exists API so are not passed
+        parameters.withPreference(getSourceRequest.preference());
+        parameters.withRouting(getSourceRequest.routing());
+        parameters.withRefresh(getSourceRequest.refresh());
+        parameters.withRealtime(getSourceRequest.realtime());
+        parameters.withFetchSourceContext(getSourceRequest.fetchSourceContext());
+
+        String endpoint = endpoint(getSourceRequest.index(), "_source", getSourceRequest.id());
+        Request request = new Request(HttpGet.METHOD_NAME, endpoint);
         request.addParameters(parameters.asMap());
         return request;
     }

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

@@ -56,6 +56,8 @@
 import org.elasticsearch.action.update.UpdateResponse;
 import org.elasticsearch.client.core.CountRequest;
 import org.elasticsearch.client.core.CountResponse;
+import org.elasticsearch.client.core.GetSourceRequest;
+import org.elasticsearch.client.core.GetSourceResponse;
 import org.elasticsearch.client.core.MainRequest;
 import org.elasticsearch.client.core.MainResponse;
 import org.elasticsearch.client.core.MultiTermVectorsRequest;
@@ -860,6 +862,34 @@ public final Cancellable existsSourceAsync(GetRequest getRequest, RequestOptions
             RestHighLevelClient::convertExistsResponse, listener, emptySet());
     }
 
+    /**
+     * Retrieves the source field only of a document using GetSource API.
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-get.html#_source">Get Source API
+     * on elastic.co</a>
+     * @param getRequest the request
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @return the response
+     */
+    public GetSourceResponse getSource(GetSourceRequest getRequest, RequestOptions options) throws IOException {
+        return performRequestAndParseEntity(getRequest, RequestConverters::getSource, options,
+            GetSourceResponse::fromXContent, emptySet());
+    }
+
+    /**
+     * Asynchronously retrieves the source field only of a document using GetSource API.
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-get.html#_source">Get Source API
+     * on elastic.co</a>
+     * @param getRequest the request
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @param listener the listener to be notified upon request completion
+     * @return cancellable that may be used to cancel the request
+     */
+    public final Cancellable getSourceAsync(GetSourceRequest getRequest, RequestOptions options,
+                                            ActionListener<GetSourceResponse> listener) {
+        return performRequestAsyncAndParseEntity(getRequest, RequestConverters::getSource, options,
+            GetSourceResponse::fromXContent, listener, emptySet());
+    }
+
     /**
      * Index a document using the Index API.
      * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-index_.html">Index API on elastic.co</a>

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

@@ -0,0 +1,126 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.client.core;
+
+import org.elasticsearch.client.Validatable;
+import org.elasticsearch.common.xcontent.ToXContentObject;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
+
+import java.io.IOException;
+
+public final class GetSourceRequest implements Validatable, ToXContentObject {
+    private String routing;
+    private String preference;
+
+    private boolean refresh = false;
+    private boolean realtime = true;
+
+    private FetchSourceContext fetchSourceContext;
+
+    private String index;
+    private String id;
+
+    public GetSourceRequest(String index, String id) {
+        this.index = index;
+        this.id = id;
+    }
+
+    /**
+     * Controls the shard routing of the request. Using this value to hash the shard
+     * and not the id.
+     */
+    public GetSourceRequest routing(String routing) {
+        if (routing != null && routing.length() == 0) {
+            this.routing = null;
+        } else {
+            this.routing = routing;
+        }
+        return this;
+    }
+
+    /**
+     * Sets the preference to execute the search. Defaults to randomize across shards. Can be set to
+     * {@code _local} to prefer local shards or a custom value, which guarantees that the same order
+     * will be used across different requests.
+     */
+    public GetSourceRequest preference(String preference) {
+        this.preference = preference;
+        return this;
+    }
+
+    /**
+     * Should a refresh be executed before this get operation causing the operation to
+     * return the latest value. Note, heavy get should not set this to {@code true}. Defaults
+     * to {@code false}.
+     */
+    public GetSourceRequest refresh(boolean refresh) {
+        this.refresh = refresh;
+        return this;
+    }
+
+    public GetSourceRequest realtime(boolean realtime) {
+        this.realtime = realtime;
+        return this;
+    }
+
+    /**
+     * Allows setting the {@link FetchSourceContext} for this request, controlling if and how _source should be returned.
+     * Note, the {@code fetchSource} field of the context must be set to {@code true}.
+     */
+
+    public GetSourceRequest fetchSourceContext(FetchSourceContext context) {
+        this.fetchSourceContext = context;
+        return this;
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        return null;
+    }
+
+    public String index() {
+        return index;
+    }
+
+    public String id() {
+        return id;
+    }
+
+    public String routing() {
+        return routing;
+    }
+
+    public String preference() {
+        return preference;
+    }
+
+    public boolean refresh() {
+        return refresh;
+    }
+
+    public boolean realtime() {
+        return realtime;
+    }
+
+    public FetchSourceContext fetchSourceContext() {
+        return fetchSourceContext;
+    }
+}

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

@@ -0,0 +1,47 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.client.core;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+
+import java.io.IOException;
+import java.util.Map;
+
+public final class GetSourceResponse {
+
+    private final Map<String, Object> source;
+
+    public GetSourceResponse(Map<String, Object> source) {
+        this.source = source;
+    }
+
+    public static GetSourceResponse fromXContent(XContentParser parser) throws IOException {
+        return new GetSourceResponse(parser.map());
+    }
+
+    public Map<String, Object> getSource() {
+        return this.source;
+    }
+
+    @Override
+    public String toString() {
+        return source.toString();
+    }
+}

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

@@ -38,6 +38,8 @@
 import org.elasticsearch.action.support.WriteRequest.RefreshPolicy;
 import org.elasticsearch.action.update.UpdateRequest;
 import org.elasticsearch.action.update.UpdateResponse;
+import org.elasticsearch.client.core.GetSourceRequest;
+import org.elasticsearch.client.core.GetSourceResponse;
 import org.elasticsearch.client.core.MultiTermVectorsRequest;
 import org.elasticsearch.client.core.MultiTermVectorsResponse;
 import org.elasticsearch.client.core.TermVectorsRequest;
@@ -70,6 +72,7 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
@@ -456,6 +459,71 @@ public void testMultiGetWithTypes() throws IOException {
         assertEquals("id2", secondResponse.getId());
     }
 
+    public void testGetSource() throws IOException {
+        {
+            GetSourceRequest getRequest = new GetSourceRequest("index", "id");
+            ElasticsearchException exception = expectThrows(ElasticsearchException.class,
+                () -> execute(getRequest, highLevelClient()::getSource, highLevelClient()::getSourceAsync));
+            assertEquals(RestStatus.NOT_FOUND, exception.status());
+            assertEquals("Elasticsearch exception [type=index_not_found_exception, reason=no such index [index]]", exception.getMessage());
+            assertEquals("index", exception.getMetadata("es.index").get(0));
+        }
+        IndexRequest index = new IndexRequest("index").id("id");
+        String document = "{\"field1\":\"value1\",\"field2\":\"value2\"}";
+        index.source(document, XContentType.JSON);
+        index.setRefreshPolicy(RefreshPolicy.IMMEDIATE);
+        highLevelClient().index(index, RequestOptions.DEFAULT);
+        {
+            GetSourceRequest getRequest = new GetSourceRequest("index", "id");
+            GetSourceResponse response = execute(getRequest, highLevelClient()::getSource, highLevelClient()::getSourceAsync);
+            Map<String, Object> expectedResponse = new HashMap<>();
+            expectedResponse.put("field1", "value1");
+            expectedResponse.put("field2", "value2");
+            assertEquals(expectedResponse, response.getSource());
+        }
+        {
+            GetSourceRequest getRequest = new GetSourceRequest("index", "does_not_exist");
+            ElasticsearchException exception = expectThrows(ElasticsearchException.class,
+                () -> execute(getRequest, highLevelClient()::getSource, highLevelClient()::getSourceAsync));
+            assertEquals(RestStatus.NOT_FOUND, exception.status());
+            assertEquals("Elasticsearch exception [type=resource_not_found_exception, " +
+                "reason=Document not found [index]/[_doc]/[does_not_exist]]", exception.getMessage());
+        }
+        {
+            GetSourceRequest getRequest = new GetSourceRequest("index", "id");
+            getRequest.fetchSourceContext(new FetchSourceContext(true, Strings.EMPTY_ARRAY, Strings.EMPTY_ARRAY));
+            GetSourceResponse response = execute(getRequest, highLevelClient()::getSource, highLevelClient()::getSourceAsync);
+            Map<String, Object> expectedResponse = new HashMap<>();
+            expectedResponse.put("field1", "value1");
+            expectedResponse.put("field2", "value2");
+            assertEquals(expectedResponse, response.getSource());
+        }
+        {
+            GetSourceRequest getRequest = new GetSourceRequest("index", "id");
+            getRequest.fetchSourceContext(new FetchSourceContext(true, new String[]{"field1"}, Strings.EMPTY_ARRAY));
+            GetSourceResponse response = execute(getRequest, highLevelClient()::getSource, highLevelClient()::getSourceAsync);
+            Map<String, Object> expectedResponse = new HashMap<>();
+            expectedResponse.put("field1", "value1");
+            assertEquals(expectedResponse, response.getSource());
+        }
+        {
+            GetSourceRequest getRequest = new GetSourceRequest("index", "id");
+            getRequest.fetchSourceContext(new FetchSourceContext(true, Strings.EMPTY_ARRAY, new String[]{"field1"}));
+            GetSourceResponse response = execute(getRequest, highLevelClient()::getSource, highLevelClient()::getSourceAsync);
+            Map<String, Object> expectedResponse = new HashMap<>();
+            expectedResponse.put("field2", "value2");
+            assertEquals(expectedResponse, response.getSource());
+        }
+        {
+            GetSourceRequest getRequest = new GetSourceRequest("index", "id");
+            getRequest.fetchSourceContext(new FetchSourceContext(false));
+            ElasticsearchException exception = expectThrows(ElasticsearchException.class,
+                () -> execute(getRequest, highLevelClient()::getSource, highLevelClient()::getSourceAsync));
+            assertEquals("Elasticsearch exception [type=action_request_validation_exception, " +
+                "reason=Validation Failed: 1: fetching source can not be disabled;]", exception.getMessage());
+        }
+    }
+
     public void testIndex() throws IOException {
         final XContentType xContentType = randomFrom(XContentType.values());
         {