JSON: Fix incorrect translation of null to "null". (#4939)

api/src/test/java/io/druid/data/input/impl/JSONParseSpecTest.java

@@ -22,17 +22,63 @@ package io.druid.data.input.impl;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.collect.ImmutableList;
 import io.druid.TestObjectMapper;
+import io.druid.java.util.common.parsers.JSONPathFieldSpec;
+import io.druid.java.util.common.parsers.JSONPathFieldType;
+import io.druid.java.util.common.parsers.JSONPathSpec;
+import io.druid.java.util.common.parsers.Parser;
 import org.junit.Assert;
 import org.junit.Test;
 
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.Map;
 
 public class JSONParseSpecTest
 {
   private final ObjectMapper jsonMapper = new TestObjectMapper();
 
+  @Test
+  public void testParseRow()
+  {
+    final JSONParseSpec parseSpec = new JSONParseSpec(
+        new TimestampSpec("timestamp", "iso", null),
+        new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("bar", "foo")), null, null),
+        new JSONPathSpec(
+            true,
+            ImmutableList.of(
+                new JSONPathFieldSpec(JSONPathFieldType.ROOT, "root_baz", "baz"),
+                new JSONPathFieldSpec(JSONPathFieldType.ROOT, "root_baz2", "baz2"),
+                new JSONPathFieldSpec(JSONPathFieldType.PATH, "path_omg", "$.o.mg"),
+                new JSONPathFieldSpec(JSONPathFieldType.PATH, "path_omg2", "$.o.mg2"),
+                new JSONPathFieldSpec(JSONPathFieldType.JQ, "jq_omg", ".o.mg"),
+                new JSONPathFieldSpec(JSONPathFieldType.JQ, "jq_omg2", ".o.mg2")
+            )
+        ),
+        null
+    );
+
+    final Map<String, Object> expected = new HashMap<>();
+    expected.put("foo", "x");
+    expected.put("baz", 4L);
+    expected.put("root_baz", 4L);
+    expected.put("root_baz2", null);
+    expected.put("path_omg", 1L);
+    expected.put("path_omg2", null);
+    expected.put("jq_omg", 1L);
+    expected.put("jq_omg2", null);
+
+    final Parser<String, Object> parser = parseSpec.makeParser();
+    final Map<String, Object> parsedRow = parser.parse("{\"bar\":null,\"foo\":\"x\",\"baz\":4,\"o\":{\"mg\":1}}");
+    Assert.assertNotNull(parsedRow);
+    Assert.assertEquals(expected, parsedRow);
+    Assert.assertNull(parsedRow.get("bar"));
+    Assert.assertNull(parsedRow.get("buzz"));
+    Assert.assertNull(parsedRow.get("root_baz2"));
+    Assert.assertNull(parsedRow.get("jq_omg2"));
+    Assert.assertNull(parsedRow.get("path_omg2"));
+  }
+
   @Test
   public void testSerde() throws IOException
   {

java-util/src/main/java/io/druid/java/util/common/parsers/JSONFlattenerMaker.java

@@ -100,7 +100,7 @@ public class JSONFlattenerMaker implements ObjectFlatteners.FlattenerMaker<JsonN
   @Nullable
   private Object valueConversionFunction(JsonNode val)
   {
-    if (val == null) {
+    if (val == null || val.isNull()) {
       return null;
     }
 

java-util/src/main/java/io/druid/java/util/common/parsers/ObjectFlatteners.java

@@ -78,7 +78,7 @@ public class ObjectFlatteners
           @Override
           public int size()
           {
-            throw new UnsupportedOperationException();
+            return keySet().size();
           }
 
           @Override