Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/2069#discussion_r66591683
--- Diff:
flink-streaming-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/util/serialization/JsonRowDeserializationSchema.java
---
@@ -0,0 +1,116 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF 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.apache.flink.streaming.util.serialization;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.java.typeutils.TypeExtractor;
+import org.apache.flink.api.table.Row;
+import org.apache.flink.api.table.typeutils.RowTypeInfo;
+import org.apache.flink.util.Preconditions;
+
+import java.io.IOException;
+
+/**
+ * Deserialization schema from JSON to {@link Row}.
+ *
+ * <p>Deserializes the <code>byte[]</code> messages as a JSON object and
reads
+ * the specified fields.
+ *
+ * <p>Failure during deserialization are forwarded as wrapped IOExceptions.
+ */
+public class JsonRowDeserializationSchema implements
DeserializationSchema<Row> {
+
+ /** Field names to parse. Indices match fieldTypes indices. */
+ private final String[] fieldNames;
+
+ /** Types to parse fields as. Indices match fieldNames indices. */
+ private final TypeInformation<?>[] fieldTypes;
+
+ /** Object mapper for parsing the JSON. */
+ private final ObjectMapper objectMapper = new ObjectMapper();
+
+ /**
+ * Creates a JSON deserializtion schema for the given fields and type
classes.
+ *
+ * @param fieldNames Names of JSON fields to parse.
+ * @param fieldTypes Type classes to parse JSON fields as.
+ */
+ public JsonRowDeserializationSchema(String[] fieldNames, Class<?>[]
fieldTypes) {
+ this.fieldNames = Preconditions.checkNotNull(fieldNames, "Field
names");
+
+ this.fieldTypes = new TypeInformation[fieldTypes.length];
+ for (int i = 0; i < fieldTypes.length; i++) {
+ this.fieldTypes[i] =
TypeExtractor.getForClass(fieldTypes[i]);
+ }
+
+ Preconditions.checkArgument(fieldNames.length ==
fieldTypes.length,
+ "Number of provided field names and types does
not match.");
+ }
+
+ /**
+ * Creates a JSON deserializtion schema for the given fields and types.
+ *
+ * @param fieldNames Names of JSON fields to parse.
+ * @param fieldTypes Types to parse JSON fields as.
+ */
+ public JsonRowDeserializationSchema(String[] fieldNames,
TypeInformation<?>[] fieldTypes) {
+ this.fieldNames = Preconditions.checkNotNull(fieldNames, "Field
names");
+ this.fieldTypes = Preconditions.checkNotNull(fieldTypes, "Field
types");
+
+ Preconditions.checkArgument(fieldNames.length ==
fieldTypes.length,
+ "Number of provided field names and types does
not match.");
+ }
+
+ @Override
+ public Row deserialize(byte[] message) throws IOException {
+ try {
+ JsonNode root = objectMapper.readTree(message);
+
+ Row row = new Row(fieldNames.length);
+ for (int i = 0; i < fieldNames.length; i++) {
+ JsonNode node = root.get(fieldNames[i]);
+
+ if (node == null) {
--- End diff --
Should we make the behavior for `node == null` configurable? An alternative
could be to tolerate missing fields and set them to `null`.
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