Implement json formatter

common/build.gradle

@@ -12,4 +12,4 @@ dependencies {
     compile group: 'com.google.guava', name: 'guava', version:'23.0'
 
     testCompile group: 'junit', name: 'junit', version: '4.12'
-}
+}

protocol/src/main/java/com/amazon/opendistroforelasticsearch/sql/protocol/response/QueryResponse.java

@@ -0,0 +1,83 @@
+/*
+ *    Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License").
+ *    You may not use this file except in compliance with the License.
+ *    A copy of the License is located at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    or in the "license" file accompanying this file. This file 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 com.amazon.opendistroforelasticsearch.sql.protocol.response;
+
+import com.amazon.opendistroforelasticsearch.sql.data.model.ExprValue;
+import com.amazon.opendistroforelasticsearch.sql.data.model.ExprValueUtils;
+import lombok.RequiredArgsConstructor;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * Query response that encapsulates query results and isolate expression related class from formatter implementation.
+ */
+@RequiredArgsConstructor
+public class QueryResponse implements Iterable<Object[]> {
+
+    /**
+     * Results which are collection of expression
+     */
+    private final Collection<ExprValue> exprValues;
+
+    /**
+     * Parse column name from results
+     * @return  mapping from column names to its expression type
+     */
+    public Map<String, String> columnNameTypes() {
+        if (exprValues.isEmpty()) {
+            return Collections.emptyMap();
+        }
+
+        Map<String, ExprValue> tupleValue = getFirstTupleValue();
+        return populateColumnNameAndTypes(tupleValue);
+    }
+
+    private Map<String, ExprValue> getFirstTupleValue() {
+        // Assume expression is always tuple on first level and columns of all tuples are exactly same
+        ExprValue firstValue = exprValues.iterator().next();
+        return ExprValueUtils.getTupleValue(firstValue);
+    }
+
+    private Map<String, String> populateColumnNameAndTypes(Map<String, ExprValue> tupleValue) {
+        Map<String, String> colNameTypes = new LinkedHashMap<>(); // Maintain original order in tuple expression
+        tupleValue.forEach((name, expr) -> {
+            colNameTypes.put(name, expr.type().name().toLowerCase());
+        });
+        return colNameTypes;
+    }
+
+    @Override
+    public Iterator<Object[]> iterator() {
+        // Any chance to avoid copy for json response generation?
+        return exprValues.stream().
+                          map(ExprValueUtils::getTupleValue).
+                          map(Map::values).
+                          map(this::convertExprValuesToValues).
+                          iterator();
+    }
+
+    private Object[] convertExprValuesToValues(Collection<ExprValue> exprValues) {
+        return exprValues.stream().
+                          map(ExprValue::value).
+                          toArray(Object[]::new);
+    }
+
+}

protocol/src/main/java/com/amazon/opendistroforelasticsearch/sql/protocol/response/format/SimpleJsonResponseFormatter.java

@@ -16,6 +16,7 @@
 
 package com.amazon.opendistroforelasticsearch.sql.protocol.response.format;
 
+import com.amazon.opendistroforelasticsearch.sql.protocol.response.QueryResponse;
 import lombok.Builder;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
@@ -40,18 +41,23 @@
  *  }
  * </pre>
  */
-public class SimpleJsonResponseFormatter extends JsonResponseFormatter<List<Object>> {
+public class SimpleJsonResponseFormatter extends JsonResponseFormatter<QueryResponse> {
 
     public SimpleJsonResponseFormatter(Style style) {
         super(style);
     }
 
     @Override
-    public Object buildJsonObject(List<Object> objects) {
-        return JsonResponse.builder().
-                            column(new Column("firstname")).
-                            row(new DataRow(new Object[]{"John"})).
-                            build();
+    public Object buildJsonObject(QueryResponse response) {
+        JsonResponse.JsonResponseBuilder json = JsonResponse.builder();
+        response.columnNameTypes().forEach((name, type) -> {
+            json.column(new Column(name, type));
+        });
+
+        for (Object[] values : response) {
+            json.row(new DataRow(values));
+        }
+        return json.build();
     }
 
     @Override
@@ -76,6 +82,7 @@ public static class JsonResponse {
     @Getter
     public static class Column {
         private final String name;
+        private final String type;
     }
 
     @RequiredArgsConstructor

protocol/src/test/java/com/amazon/opendistroforelasticsearch/sql/protocol/response/format/JsonResponseFormatterTest.java

@@ -16,10 +16,14 @@
 
 package com.amazon.opendistroforelasticsearch.sql.protocol.response.format;
 
+import com.amazon.opendistroforelasticsearch.sql.protocol.response.QueryResponse;
+import com.google.common.collect.ImmutableMap;
 import org.junit.jupiter.api.Test;
 
+import java.util.Arrays;
 import java.util.Collections;
 
+import static com.amazon.opendistroforelasticsearch.sql.data.model.ExprValueUtils.tupleValue;
 import static com.amazon.opendistroforelasticsearch.sql.protocol.response.format.JsonResponseFormatter.Style.COMPACT;
 import static com.amazon.opendistroforelasticsearch.sql.protocol.response.format.JsonResponseFormatter.Style.PRETTY;
 import static org.junit.jupiter.api.Assertions.assertEquals;
@@ -28,22 +32,49 @@ class JsonResponseFormatterTest {
 
     @Test
     public void formatResponse() {
+        QueryResponse response = new QueryResponse(Arrays.asList(
+            tupleValue(ImmutableMap.of("firstname", "John", "age", 20)),
+            tupleValue(ImmutableMap.of("firstname", "Smith", "age", 30))
+        ));
         SimpleJsonResponseFormatter formatter = new SimpleJsonResponseFormatter(COMPACT);
         assertEquals(
-            "{\"schema\":[{\"name\":\"firstname\"}],\"datarows\":[{\"row\":[\"John\"]}]}",
-            formatter.format(Collections.emptyList())
+            "{\"schema\":[{\"name\":\"firstname\",\"type\":\"string\"},{\"name\":\"age\",\"type\":\"integer\"}],"
+                + "\"datarows\":[{\"row\":[\"John\",20]},{\"row\":[\"Smith\",30]}]}",
+            formatter.format(response)
         );
     }
 
     @Test
     public void formatResponsePretty() {
+        QueryResponse response = new QueryResponse(Arrays.asList(
+            tupleValue(ImmutableMap.of("firstname", "John", "age", 20)),
+            tupleValue(ImmutableMap.of("firstname", "Smith", "age", 30))
+        ));
         SimpleJsonResponseFormatter formatter = new SimpleJsonResponseFormatter(PRETTY);
         assertEquals(
             "{\n" +
-            "  \"schema\": [{\"name\": \"firstname\"}],\n" +
-            "  \"datarows\": [{\"row\": [\"John\"]}]\n" +
+            "  \"schema\": [\n" +
+            "    {\n" +
+            "      \"name\": \"firstname\",\n" +
+            "      \"type\": \"string\"\n" +
+            "    },\n" +
+            "    {\n" +
+            "      \"name\": \"age\",\n" +
+            "      \"type\": \"integer\"\n" +
+            "    }\n" +
+            "  ],\n" +
+            "  \"datarows\": [\n" +
+            "    {\"row\": [\n" +
+            "      \"John\",\n" +
+            "      20\n" +
+            "    ]},\n" +
+            "    {\"row\": [\n" +
+            "      \"Smith\",\n" +
+            "      30\n" +
+            "    ]}\n" +
+            "  ]\n" +
             "}",
-            formatter.format(Collections.emptyList())
+            formatter.format(response)
         );
     }