[GitHub] [iceberg] rdblue commented on a change in pull request #1175: Flink: Add wrapper to adapt Row to StructLike

[GitBox <gi...@apache.org>]

rdblue commented on a change in pull request #1175:
URL: https://github.com/apache/iceberg/pull/1175#discussion_r455279084



##########
File path: flink/src/main/java/org/apache/iceberg/flink/RowWrapper.java
##########
@@ -0,0 +1,85 @@
+/*
+ * 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.iceberg.flink;
+
+import java.lang.reflect.Array;
+import org.apache.flink.types.Row;
+import org.apache.iceberg.StructLike;
+import org.apache.iceberg.types.Type;
+import org.apache.iceberg.types.Types;
+
+public class RowWrapper implements StructLike {
+
+  private final Type[] types;
+  private final PositionalGetter[] getters;
+  private Row row = null;
+
+  public RowWrapper(Types.StructType type) {
+    int size = type.fields().size();
+
+    types = (Type[]) Array.newInstance(Type.class, size);
+    for (int i = 0; i < size; i++) {
+      types[i] = type.fields().get(i).type();
+    }
+
+    getters = (PositionalGetter[]) Array.newInstance(PositionalGetter.class, size);
+    for (int i = 0; i < size; i++) {
+      getters[i] = buildGetter(types[i]);
+    }
+  }
+
+  RowWrapper wrap(Row data) {
+    this.row = data;
+    return this;
+  }
+
+  @Override
+  public int size() {
+    return types.length;
+  }
+
+  @Override
+  public <T> T get(int pos, Class<T> javaClass) {
+    if (row.getField(pos) == null) {
+      return null;
+    } else if (getters[pos] != null) {
+      return javaClass.cast(getters[pos].get(row, pos));
+    }
+
+    return javaClass.cast(row.getField(pos));
+  }
+
+  @Override
+  public <T> void set(int pos, T value) {
+    row.setField(pos, value);
+  }
+
+  private interface PositionalGetter<T> {
+    T get(Row row, int pos);
+  }
+
+  private static PositionalGetter buildGetter(Type type) {
+    if (type instanceof Types.StructType) {

Review comment:
       Yes, this needs to convert to the representation that internal classes use.
   
   Iceberg's generic data model is intended for passing data to and from Java applications, which is why they use friendlier classes. It is up to data models like Iceberg generics or Flink's data model to convert to that representation. Iceberg core should modify data as little as possible.




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