Github user fhueske commented on a diff in the pull request: https://github.com/apache/flink/pull/3663#discussion_r113179472 --- Diff: flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/connectors/kafka/KafkaAvroTableSource.java --- @@ -0,0 +1,117 @@ +/* + * 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.connectors.kafka; + +import java.util.List; +import java.util.Properties; +import org.apache.avro.Schema; +import org.apache.avro.specific.SpecificData; +import org.apache.avro.specific.SpecificRecord; +import org.apache.avro.specific.SpecificRecordBase; +import org.apache.avro.util.Utf8; +import org.apache.flink.api.common.typeinfo.BasicTypeInfo; +import org.apache.flink.api.common.typeinfo.TypeInformation; +import org.apache.flink.api.java.typeutils.AvroTypeInfo; +import org.apache.flink.api.java.typeutils.GenericTypeInfo; +import org.apache.flink.api.java.typeutils.RowTypeInfo; +import org.apache.flink.streaming.util.serialization.AvroRowDeserializationSchema; +import org.apache.flink.streaming.util.serialization.DeserializationSchema; +import org.apache.flink.table.sources.StreamTableSource; + +/** + * A version-agnostic Kafka Avro {@link StreamTableSource}. + * + * <p>The version-specific Kafka consumers need to extend this class and + * override {@link #getKafkaConsumer(String, Properties, DeserializationSchema)}}. + */ +public abstract class KafkaAvroTableSource extends KafkaTableSource { + + /** + * Creates a generic Kafka Avro {@link StreamTableSource} using a given {@link SpecificRecord}. + * + * @param topic Kafka topic to consume. + * @param properties Properties for the Kafka consumer. + * @param record Avro specific record. + */ + KafkaAvroTableSource( + String topic, + Properties properties, + Class<? extends SpecificRecordBase> record) { + + super( + topic, + properties, + createDeserializationSchema(record), + createFieldNames(record), + createFieldTypes(record)); + } + + private static AvroRowDeserializationSchema createDeserializationSchema(Class<? extends SpecificRecordBase> record) { + return new AvroRowDeserializationSchema(record); + } + + /** + * Converts the extracted AvroTypeInfo into a RowTypeInfo nested structure with deterministic field order. + * Replaces generic Utf8 with basic String type information. + */ + private static TypeInformation<?> convertToRowTypeInformation(TypeInformation<?> extracted, Schema schema) { + if (schema.getType() == Schema.Type.RECORD) { + final List<Schema.Field> fields = schema.getFields(); + final AvroTypeInfo<?> avroTypeInfo = (AvroTypeInfo<?>) extracted; + + final TypeInformation<?>[] types = new TypeInformation<?>[fields.size()]; + final String[] names = new String[fields.size()]; + for (int i = 0; i < fields.size(); i++) { + final Schema.Field field = fields.get(i); + types[i] = convertToRowTypeInformation(avroTypeInfo.getTypeAt(field.name()), field.schema()); + names[i] = field.name(); + } + return new RowTypeInfo(types, names); + } else if (extracted instanceof GenericTypeInfo<?>) { + final GenericTypeInfo<?> genericTypeInfo = (GenericTypeInfo<?>) extracted; + if (genericTypeInfo.getTypeClass() == Utf8.class) { + return BasicTypeInfo.STRING_TYPE_INFO; + } + } + return extracted; + } + + private static <T extends SpecificRecordBase> TypeInformation<?>[] createFieldTypes(Class<T> record) { + final AvroTypeInfo<T> avroTypeInfo = new AvroTypeInfo<>(record); + // determine schema to retrieve deterministic field order + final Schema schema = SpecificData.get().getSchema(record); + final RowTypeInfo row = (RowTypeInfo) convertToRowTypeInformation(avroTypeInfo, schema); + final TypeInformation<?>[] types = new TypeInformation<?>[row.getArity()]; + for (int i = 0; i < row.getArity(); i++) { + types[i] = row.getTypeAt(i); + } + return types; + } + + private static String[] createFieldNames(Class<? extends SpecificRecord> record) { --- End diff -- `record` -> `avroClass`?
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