Add get field mappings to High Level REST API Client

Relates to #27205

(cherry picked from commit b7ef75f)

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

@@ -38,6 +38,8 @@
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeResponse;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
+import org.elasticsearch.action.admin.indices.mapping.get.GetFieldMappingsRequest;
+import org.elasticsearch.action.admin.indices.mapping.get.GetFieldMappingsResponse;
 import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsRequest;
 import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsResponse;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
@@ -268,6 +270,35 @@ public void getMappingsAsync(GetMappingsRequest getMappingsRequest, RequestOptio
             GetMappingsResponse::fromXContent, listener, emptySet());
     }
 
+    /**
+     * Retrieves the field mappings on an index or indices using the Get Field Mapping API.
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-get-field-mapping.html">
+     * Get Field Mapping API on elastic.co</a>
+     * @param getFieldMappingsRequest the request
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @return the response
+     * @throws IOException in case there is a problem sending the request or parsing back the response
+     */
+    public GetFieldMappingsResponse getFieldMapping(GetFieldMappingsRequest getFieldMappingsRequest,
+                                                    RequestOptions options) throws IOException {
+        return restHighLevelClient.performRequestAndParseEntity(getFieldMappingsRequest, RequestConverters::getFieldMapping, options,
+            GetFieldMappingsResponse::fromXContent, emptySet());
+    }
+
+    /**
+     * Asynchronously retrieves the field mappings on an index on indices using the Get Field Mapping API.
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-get-field-mapping.html">
+     * Get Field Mapping API on elastic.co</a>
+     * @param getFieldMappingsRequest 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
+     */
+    public void getFieldMappingAsync(GetFieldMappingsRequest getFieldMappingsRequest, RequestOptions options,
+                                     ActionListener<GetFieldMappingsResponse> listener) {
+        restHighLevelClient.performRequestAsyncAndParseEntity(getFieldMappingsRequest, RequestConverters::getFieldMapping, options,
+            GetFieldMappingsResponse::fromXContent, listener, emptySet());
+    }
+
     /**
      * Updates aliases using the Index Aliases API.
      * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-aliases.html">

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

@@ -50,6 +50,7 @@
 import org.elasticsearch.action.admin.indices.flush.SyncedFlushRequest;
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
+import org.elasticsearch.action.admin.indices.mapping.get.GetFieldMappingsRequest;
 import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
 import org.elasticsearch.action.admin.indices.open.OpenIndexRequest;
@@ -232,6 +233,25 @@ static Request getMappings(GetMappingsRequest getMappingsRequest) throws IOExcep
         return request;
     }
 
+    static Request getFieldMapping(GetFieldMappingsRequest getFieldMappingsRequest) throws IOException {
+        String[] indices = getFieldMappingsRequest.indices() == null ? Strings.EMPTY_ARRAY : getFieldMappingsRequest.indices();
+        String[] types = getFieldMappingsRequest.types() == null ? Strings.EMPTY_ARRAY : getFieldMappingsRequest.types();
+        String[] fields = getFieldMappingsRequest.fields() == null ? Strings.EMPTY_ARRAY : getFieldMappingsRequest.fields();
+
+        String endpoint = new EndpointBuilder().addCommaSeparatedPathParts(indices)
+            .addPathPartAsIs("_mapping").addCommaSeparatedPathParts(types)
+            .addPathPartAsIs("field").addCommaSeparatedPathParts(fields)
+            .build();
+
+        Request request = new Request(HttpGet.METHOD_NAME, endpoint);
+
+        Params parameters = new Params(request);
+        parameters.withIndicesOptions(getFieldMappingsRequest.indicesOptions());
+        parameters.withIncludeDefaults(getFieldMappingsRequest.includeDefaults());
+        parameters.withLocal(getFieldMappingsRequest.local());
+        return request;
+    }
+
     static Request refresh(RefreshRequest refreshRequest) {
         String[] indices = refreshRequest.indices() == null ? Strings.EMPTY_ARRAY : refreshRequest.indices();
         Request request = new Request(HttpPost.METHOD_NAME, endpoint(indices, "_refresh"));

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

@@ -43,6 +43,8 @@
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeResponse;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
+import org.elasticsearch.action.admin.indices.mapping.get.GetFieldMappingsRequest;
+import org.elasticsearch.action.admin.indices.mapping.get.GetFieldMappingsResponse;
 import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsRequest;
 import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsResponse;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
@@ -75,6 +77,7 @@
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.cluster.metadata.IndexTemplateMetaData;
 import org.elasticsearch.common.ValidationException;
+import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.ByteSizeUnit;
@@ -388,6 +391,41 @@ public void testGetMapping() throws IOException {
         assertThat(mappings, equalTo(expected));
     }
 
+    public void testGetFieldMapping() throws IOException {
+        String indexName = "test";
+        createIndex(indexName, Settings.EMPTY);
+
+        PutMappingRequest putMappingRequest = new PutMappingRequest(indexName);
+        putMappingRequest.type("_doc");
+        XContentBuilder mappingBuilder = JsonXContent.contentBuilder();
+        mappingBuilder.startObject().startObject("properties").startObject("field");
+        mappingBuilder.field("type", "text");
+        mappingBuilder.endObject().endObject().endObject();
+        putMappingRequest.source(mappingBuilder);
+
+        PutMappingResponse putMappingResponse =
+            execute(putMappingRequest, highLevelClient().indices()::putMapping, highLevelClient().indices()::putMappingAsync);
+        assertTrue(putMappingResponse.isAcknowledged());
+
+        GetFieldMappingsRequest getFieldMappingsRequest = new GetFieldMappingsRequest()
+            .indices(indexName)
+            .types("_doc")
+            .fields("field");
+
+        GetFieldMappingsResponse getFieldMappingsResponse =
+            execute(getFieldMappingsRequest,
+                highLevelClient().indices()::getFieldMapping,
+                highLevelClient().indices()::getFieldMappingAsync);
+
+        final Map<String, GetFieldMappingsResponse.FieldMappingMetaData> fieldMappingMap =
+            getFieldMappingsResponse.mappings().get(indexName).get("_doc");
+
+        final GetFieldMappingsResponse.FieldMappingMetaData metaData =
+            new GetFieldMappingsResponse.FieldMappingMetaData("field",
+                new BytesArray("{\"field\":{\"type\":\"text\"}}"));
+        assertThat(fieldMappingMap, equalTo(Collections.singletonMap("field", metaData)));
+    }
+
     public void testDeleteIndex() throws IOException {
         {
             // Delete index if exists

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

@@ -52,6 +52,7 @@
 import org.elasticsearch.action.admin.indices.flush.SyncedFlushRequest;
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
+import org.elasticsearch.action.admin.indices.mapping.get.GetFieldMappingsRequest;
 import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
 import org.elasticsearch.action.admin.indices.open.OpenIndexRequest;
@@ -466,6 +467,61 @@ public void testGetMapping() throws IOException {
         assertThat(HttpGet.METHOD_NAME, equalTo(request.getMethod()));
     }
 
+    public void testGetFieldMapping() throws IOException {
+        GetFieldMappingsRequest getFieldMappingsRequest = new GetFieldMappingsRequest();
+
+        String[] indices = Strings.EMPTY_ARRAY;
+        if (randomBoolean()) {
+            indices = randomIndicesNames(0, 5);
+            getFieldMappingsRequest.indices(indices);
+        } else if (randomBoolean()) {
+            getFieldMappingsRequest.indices((String[]) null);
+        }
+
+        String type = null;
+        if (randomBoolean()) {
+            type = randomAlphaOfLengthBetween(3, 10);
+            getFieldMappingsRequest.types(type);
+        } else if (randomBoolean()) {
+            getFieldMappingsRequest.types((String[]) null);
+        }
+
+        String[] fields = null;
+        if (randomBoolean()) {
+            fields = new String[randomIntBetween(1, 5)];
+            for (int i = 0; i < fields.length; i++) {
+                fields[i] = randomAlphaOfLengthBetween(3, 10);
+            }
+            getFieldMappingsRequest.fields(fields);
+        } else if (randomBoolean()) {
+            getFieldMappingsRequest.fields((String[]) null);
+        }
+
+        Map<String, String> expectedParams = new HashMap<>();
+
+        setRandomIndicesOptions(getFieldMappingsRequest::indicesOptions, getFieldMappingsRequest::indicesOptions, expectedParams);
+        setRandomLocal(getFieldMappingsRequest::local, expectedParams);
+
+        Request request = RequestConverters.getFieldMapping(getFieldMappingsRequest);
+        StringJoiner endpoint = new StringJoiner("/", "/", "");
+        String index = String.join(",", indices);
+        if (Strings.hasLength(index)) {
+            endpoint.add(index);
+        }
+        endpoint.add("_mapping");
+        if (type != null) {
+            endpoint.add(type);
+        }
+        endpoint.add("field");
+        if (fields != null) {
+            endpoint.add(String.join(",", fields));
+        }
+        assertThat(endpoint.toString(), equalTo(request.getEndpoint()));
+
+        assertThat(expectedParams, equalTo(request.getParameters()));
+        assertThat(HttpGet.METHOD_NAME, equalTo(request.getMethod()));
+    }
+
     public void testDeleteIndex() {
         String[] indices = randomIndicesNames(0, 5);
         DeleteIndexRequest deleteIndexRequest = new DeleteIndexRequest(indices);
@@ -2272,16 +2328,20 @@ private static void setRandomHumanReadable(GetIndexRequest request, Map<String,
         }
     }
 
-    private static void setRandomLocal(MasterNodeReadRequest<?> request, Map<String, String> expectedParams) {
+    private static void setRandomLocal(Consumer<Boolean> setter, Map<String, String> expectedParams) {
         if (randomBoolean()) {
             boolean local = randomBoolean();
-            request.local(local);
+            setter.accept(local);
             if (local) {
                 expectedParams.put("local", String.valueOf(local));
             }
         }
     }
 
+    private static void setRandomLocal(MasterNodeReadRequest<?> request, Map<String, String> expectedParams) {
+        setRandomLocal(request::local, expectedParams);
+    }
+
     private static void setRandomTimeout(Consumer<String> setter, TimeValue defaultTimeout, Map<String, String> expectedParams) {
         if (randomBoolean()) {
             String timeout = randomTimeValue();

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

@@ -41,6 +41,8 @@
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeResponse;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
+import org.elasticsearch.action.admin.indices.mapping.get.GetFieldMappingsRequest;
+import org.elasticsearch.action.admin.indices.mapping.get.GetFieldMappingsResponse;
 import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsRequest;
 import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsResponse;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
@@ -703,6 +705,110 @@ public void onFailure(Exception e) {
         }
     }
 
+    public void testGetFieldMapping() throws IOException, InterruptedException {
+        RestHighLevelClient client = highLevelClient();
+
+        {
+            CreateIndexResponse createIndexResponse = client.indices().create(new CreateIndexRequest("twitter"), RequestOptions.DEFAULT);
+            assertTrue(createIndexResponse.isAcknowledged());
+            PutMappingRequest request = new PutMappingRequest("twitter");
+            request.type("tweet");
+            request.source(
+                "{\n" +
+                    "  \"properties\": {\n" +
+                    "    \"message\": {\n" +
+                    "      \"type\": \"text\"\n" +
+                    "    },\n" +
+                    "    \"timestamp\": {\n" +
+                    "      \"type\": \"date\"\n" +
+                    "    }\n" +
+                    "  }\n" +
+                    "}", // <1>
+                XContentType.JSON);
+            PutMappingResponse putMappingResponse = client.indices().putMapping(request, RequestOptions.DEFAULT);
+            assertTrue(putMappingResponse.isAcknowledged());
+        }
+
+        // tag::get-field-mapping-request
+        GetFieldMappingsRequest request = new GetFieldMappingsRequest(); // <1>
+        request.indices("twitter"); // <2>
+        request.types("tweet"); // <3>
+        request.fields("message", "timestamp"); // <4>
+        // end::get-field-mapping-request
+
+        // tag::get-field-mapping-request-indicesOptions
+        request.indicesOptions(IndicesOptions.lenientExpandOpen()); // <1>
+        // end::get-field-mapping-request-indicesOptions
+
+        // tag::get-field-mapping-request-local
+        request.local(true); // <1>
+        // end::get-field-mapping-request-local
+
+        {
+
+            // tag::get-field-mapping-execute
+            GetFieldMappingsResponse response =
+                client.indices().getFieldMapping(request, RequestOptions.DEFAULT);
+            // end::get-field-mapping-execute
+
+            // tag::get-field-mapping-response
+            final Map<String, Map<String, Map<String, GetFieldMappingsResponse.FieldMappingMetaData>>> mappings =
+                response.mappings();// <1>
+            final Map<String, GetFieldMappingsResponse.FieldMappingMetaData> typeMappings =
+                mappings.get("twitter").get("tweet"); // <2>
+            final GetFieldMappingsResponse.FieldMappingMetaData metaData =
+                typeMappings.get("message");// <3>
+
+            final String fullName = metaData.fullName();// <4>
+            final Map<String, Object> source = metaData.sourceAsMap(); // <5>
+            // end::get-field-mapping-response
+        }
+
+        {
+            // tag::get-field-mapping-execute-listener
+            ActionListener<GetFieldMappingsResponse> listener =
+                new ActionListener<GetFieldMappingsResponse>() {
+                    @Override
+                    public void onResponse(GetFieldMappingsResponse putMappingResponse) {
+                        // <1>
+                    }
+
+                    @Override
+                    public void onFailure(Exception e) {
+                        // <2>
+                    }
+                };
+            // end::get-field-mapping-execute-listener
+
+            // Replace the empty listener by a blocking listener in test
+            final CountDownLatch latch = new CountDownLatch(1);
+            final ActionListener<GetFieldMappingsResponse> latchListener = new LatchedActionListener<>(listener, latch);
+            listener = ActionListener.wrap(r -> {
+                final Map<String, Map<String, Map<String, GetFieldMappingsResponse.FieldMappingMetaData>>> mappings =
+                    r.mappings();
+                final Map<String, GetFieldMappingsResponse.FieldMappingMetaData> typeMappings =
+                    mappings.get("twitter").get("tweet");
+                final GetFieldMappingsResponse.FieldMappingMetaData metaData1 = typeMappings.get("message");
+
+                final String fullName = metaData1.fullName();
+                final Map<String, Object> source = metaData1.sourceAsMap();
+                latchListener.onResponse(r);
+            }, e -> {
+                latchListener.onFailure(e);
+                fail("should not fail");
+            });
+
+            // tag::get-field-mapping-execute-async
+            client.indices().getFieldMappingAsync(request, RequestOptions.DEFAULT, listener); // <1>
+            // end::get-field-mapping-execute-async
+
+            assertTrue(latch.await(30L, TimeUnit.SECONDS));
+        }
+
+
+    }
+
+
     public void testOpenIndex() throws Exception {
         RestHighLevelClient client = highLevelClient();