[GitHub] [flink] wuchong commented on a change in pull request #11944: [FLINK-17461][formats][json] Support JSON serialization and deseriazation schema for RowData type

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wuchong commented on a change in pull request #11944:
URL: https://github.com/apache/flink/pull/11944#discussion_r417375698



##########
File path: flink-formats/flink-json/src/main/java/org/apache/flink/formats/json/JsonRowDataDeserializationSchema.java
##########
@@ -0,0 +1,492 @@
+/*
+ * 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.formats.json;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.api.common.serialization.DeserializationSchema;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.table.data.DecimalData;
+import org.apache.flink.table.data.GenericArrayData;
+import org.apache.flink.table.data.GenericMapData;
+import org.apache.flink.table.data.GenericRowData;
+import org.apache.flink.table.data.RowData;
+import org.apache.flink.table.data.StringData;
+import org.apache.flink.table.data.TimestampData;
+import org.apache.flink.table.types.logical.ArrayType;
+import org.apache.flink.table.types.logical.DecimalType;
+import org.apache.flink.table.types.logical.LogicalType;
+import org.apache.flink.table.types.logical.LogicalTypeFamily;
+import org.apache.flink.table.types.logical.MapType;
+import org.apache.flink.table.types.logical.RowType;
+import org.apache.flink.table.types.logical.utils.LogicalTypeChecks;
+import org.apache.flink.table.types.logical.utils.LogicalTypeUtils;
+
+import org.apache.flink.shaded.jackson2.com.fasterxml.jackson.databind.JsonNode;
+import org.apache.flink.shaded.jackson2.com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.flink.shaded.jackson2.com.fasterxml.jackson.databind.node.ArrayNode;
+import org.apache.flink.shaded.jackson2.com.fasterxml.jackson.databind.node.ObjectNode;
+import org.apache.flink.shaded.jackson2.com.fasterxml.jackson.databind.node.TextNode;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.lang.reflect.Array;
+import java.math.BigDecimal;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.time.ZoneOffset;
+import java.time.temporal.TemporalAccessor;
+import java.time.temporal.TemporalQueries;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+
+import static java.lang.String.format;
+import static java.time.format.DateTimeFormatter.ISO_LOCAL_DATE;
+import static org.apache.flink.formats.json.TimeFormats.RFC3339_TIMESTAMP_FORMAT;
+import static org.apache.flink.formats.json.TimeFormats.RFC3339_TIME_FORMAT;
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * Deserialization schema from JSON to Flink Table/SQL internal data structure {@link RowData}.
+ *
+ * <p>Deserializes a <code>byte[]</code> message as a JSON object and reads
+ * the specified fields.
+ *
+ * <p>Failures during deserialization are forwarded as wrapped IOExceptions.
+ */
+@Internal
+public class JsonRowDataDeserializationSchema implements DeserializationSchema<RowData> {
+	private static final long serialVersionUID = 8576854315236033439L;
+
+	/** Flag indicating whether to fail if a field is missing. */
+	private final boolean failOnMissingField;
+
+	/** Flag indicating whether to ignore invalid fields/rows (default: throw an exception). */
+	private final boolean ignoreParseErrors;
+
+	/** TypeInformation of the produced {@link RowData}. **/
+	private final TypeInformation<RowData> resultTypeInfo;
+
+	/**
+	 * Runtime converter that converts {@link JsonNode}s into
+	 * objects of Flink SQL internal data structures. **/
+	private final DeserializationRuntimeConverter runtimeConverter;
+
+	/** Object mapper for parsing the JSON. */
+	private final ObjectMapper objectMapper = new ObjectMapper();
+
+	/**
+	 * Creates a builder for {@link JsonRowDataDeserializationSchema}.
+	 */
+	public static Builder builder() {
+		return new Builder();
+	}
+
+	private JsonRowDataDeserializationSchema(
+			RowType rowType,
+			TypeInformation<RowData> resultTypeInfo,
+			boolean failOnMissingField,
+			boolean ignoreParseErrors) {
+		if (ignoreParseErrors && failOnMissingField) {
+			throw new IllegalArgumentException(
+				"JSON format doesn't support failOnMissingField and ignoreParseErrors are both enabled.");
+		}
+		this.resultTypeInfo = checkNotNull(resultTypeInfo);
+		this.failOnMissingField = failOnMissingField;
+		this.ignoreParseErrors = ignoreParseErrors;
+		this.runtimeConverter = createRowConverter(checkNotNull(rowType));
+	}
+
+	@Override
+	public RowData deserialize(byte[] message) throws IOException {
+		try {
+			final JsonNode root = objectMapper.readTree(message);
+			return (RowData) runtimeConverter.convert(root);
+		} catch (Throwable t) {
+			if (ignoreParseErrors) {
+				return null;
+			}
+			throw new IOException(format("Failed to deserialize JSON '%s'.", new String(message)), t);
+		}
+	}
+
+	@Override
+	public boolean isEndOfStream(RowData nextElement) {
+		return false;
+	}
+
+	@Override
+	public TypeInformation<RowData> getProducedType() {
+		return resultTypeInfo;
+	}
+
+	// -------------------------------------------------------------------------------------
+	// Builder
+	// -------------------------------------------------------------------------------------
+
+	/**
+	 * Builder for {@link JsonRowDataDeserializationSchema}.
+	 */
+	public static class Builder {

Review comment:
       I think we will support more and more options for JSON in the future. A builder is more friendly to evolve without breaking constructors. But I'm also fine to remove builders because this is an `@Internal` class. 




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