Support JSON Schema converter

src/main/java/com/snowflake/kafka/connector/records/SnowflakeJsonSchemaConverter.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2019 Snowflake Inc. 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.  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 com.snowflake.kafka.connector.records;
+
+import java.nio.ByteBuffer;
+
+import com.snowflake.kafka.connector.internal.SnowflakeErrors;
+import org.apache.kafka.connect.data.SchemaAndValue;
+
+public class SnowflakeJsonSchemaConverter extends SnowflakeConverter {
+  /**
+   * cast bytes array to Json array
+   *
+   * @param s topic name. unused
+   * @param bytes input bytes array, only support single json record now
+   * @return JSON array
+   */
+  @Override
+  public SchemaAndValue toConnectData(final String s, final byte[] bytes) {
+    if (bytes == null) {
+      return new SchemaAndValue(new SnowflakeJsonSchema(), new SnowflakeRecordContent());
+    }
+    ByteBuffer buffer;
+    int id;
+    try {
+      buffer = ByteBuffer.wrap(bytes);
+      if (buffer.get() != 0) {
+        throw SnowflakeErrors.ERROR_0010.getException("unknown bytes");
+      }
+      id = buffer.getInt();
+    } catch (Exception ex) {
+      LOGGER.error("Failed to parse schema-prepended JSON record\n" + ex.getMessage());
+      return new SchemaAndValue(new SnowflakeJsonSchema(), new SnowflakeRecordContent(bytes));
+    }
+
+    try {
+      int length = buffer.limit() - 1 - 4;
+      byte[] data = new byte[length];
+      buffer.get(data, 0, length);
+
+      return new SchemaAndValue(
+              new SnowflakeJsonSchema(), new SnowflakeRecordContent(mapper.readTree(data), id));
+    } catch (Exception ex) {
+      LOGGER.error("Failed to parse JSON record\n" + ex.toString());
+      return new SchemaAndValue(new SnowflakeJsonSchema(), new SnowflakeRecordContent(bytes));
+    }
+  }
+}

src/test/java/com/snowflake/kafka/connector/records/ConverterTest.java

@@ -18,6 +18,7 @@
 
 import static com.snowflake.kafka.connector.records.RecordService.ISO_DATE_TIME_FORMAT;
 
+import com.google.common.collect.Sets;
 import com.snowflake.kafka.connector.internal.SnowflakeKafkaConnectorException;
 import com.snowflake.kafka.connector.mock.MockSchemaRegistryClient;
 import io.confluent.connect.avro.AvroConverter;
@@ -28,20 +29,13 @@
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.net.URL;
+import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Calendar;
-import java.util.Collections;
-import java.util.GregorianCalendar;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.TimeZone;
+import java.util.*;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
@@ -109,6 +103,34 @@ public void testJsonConverter() {
     assert ((SnowflakeRecordContent) sv.value()).getData()[0].toString().equals("{}");
   }
 
+  @Test
+  public void testConnectJsonSchemaConverter() {
+    SnowflakeJsonSchemaConverter converter = new SnowflakeJsonSchemaConverter();
+    ByteBuffer buffer = ByteBuffer.allocate(29);
+    int schemaId = 33;
+    buffer.put((byte)0).putInt(schemaId).put("{\"str\":\"test\",\"num\":123}".getBytes(StandardCharsets.UTF_8));
+
+    SchemaAndValue sv =
+            converter.toConnectData("test", buffer.array());
+
+    assert sv.schema().name().equals(SnowflakeJsonSchema.NAME);
+
+    assert sv.value() instanceof SnowflakeRecordContent;
+
+    SnowflakeRecordContent content = (SnowflakeRecordContent) sv.value();
+    assert content.getSchemaID() == schemaId;
+
+    JsonNode[] jsonNodes = content.getData();
+
+    assert jsonNodes.length == 1;
+    assert jsonNodes[0].size() == 2;
+    assert Sets.newHashSet(jsonNodes[0].fieldNames()).containsAll(Arrays.asList("str", "num"));
+    assert jsonNodes[0].get("str").isTextual();
+    assert jsonNodes[0].get("str").asText().equals("test");
+    assert jsonNodes[0].get("num").isInt();
+    assert jsonNodes[0].get("num").asInt() == 123;
+  }
+
   @Test
   public void testAvroConverter() throws IOException {
     // todo: test schema registry