snuyanzin commented on code in PR #26704: URL: https://github.com/apache/flink/pull/26704#discussion_r2158899340
########## flink-table/flink-table-common/src/main/java/org/apache/flink/table/types/inference/strategies/ObjectOfInputTypeStrategy.java: ########## @@ -0,0 +1,175 @@ +/* + * 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.table.types.inference.strategies; + +import org.apache.flink.table.api.ValidationException; +import org.apache.flink.table.functions.FunctionDefinition; +import org.apache.flink.table.types.DataType; +import org.apache.flink.table.types.inference.ArgumentCount; +import org.apache.flink.table.types.inference.CallContext; +import org.apache.flink.table.types.inference.InputTypeStrategy; +import org.apache.flink.table.types.inference.Signature; +import org.apache.flink.table.types.logical.LogicalType; +import org.apache.flink.table.types.logical.LogicalTypeFamily; + +import java.util.ArrayList; +import java.util.HashSet; +import java.util.List; +import java.util.Optional; +import java.util.Set; + +/** + * Input type strategy for the {@code OBJECT_OF} function that validates argument types and counts. + * + * <p>This strategy validates the input arguments for the {@code OBJECT_OF} function, ensuring: + * + * <ul> + * <li>The argument count is odd (className + pairs of key-value arguments) + * <li>The first argument is a STRING/VARCHAR representing the class name + * <li>All key arguments (odd positions after the first) are STRING/VARCHAR types + * <li>Field names are unique across all key-value pairs + * <li>Value arguments (even positions after the first) can be any type + * </ul> + * + * <p>The expected function signature is: {@code OBJECT_OF(className, key1, value1, key2, value2, + * ...)} + * + * <p>Validation rules: + * + * <ul> + * <li>Minimum 1 argument (just the class name) + * <li>Odd total number of arguments (className + key-value pairs) + * <li>Keys must be string literals for field name extraction + * <li>No duplicate field names allowed + * </ul> + * + * <p><b>Note: Users are responsible for providing a valid fully qualified class name that exists in + * the classpath. The class name should follow Java naming conventions. While this strategy + * validates the format and type of the class name argument, it does not verify the class existence + * in the classpath. If an invalid or non-existent class name is provided, the function will fall + * back to using Row.class as the type representation.</b> + * + * <p>Example valid calls: + * + * <ul> + * <li>{@code OBJECT_OF('com.example.User')} - empty object + * <li>{@code OBJECT_OF('com.example.User', 'name', 'Alice')} - single field + * <li>{@code OBJECT_OF('com.example.User', 'name', 'Alice', 'age', 30)} - multiple fields + * </ul> + * + * @see org.apache.flink.table.functions.BuiltInFunctionDefinitions#OBJECT_OF + * @see ObjectOfTypeStrategy + */ +public class ObjectOfInputTypeStrategy implements InputTypeStrategy { + + private static final ArgumentCount AT_LEAST_ONE_ODD = + new ArgumentCount() { + @Override + public boolean isValidCount(int count) { + return count % 2 == 1; + } + + @Override + public Optional<Integer> getMinCount() { + return Optional.of(1); + } + + @Override + public Optional<Integer> getMaxCount() { + return Optional.empty(); + } + }; + + private static void validateClassInput( + final CallContext callContext, final List<DataType> argumentDataTypes) { + final LogicalType classArgumentType = argumentDataTypes.get(0).getLogicalType(); + + final String errorMessage = + "The first argument must be a STRING/VARCHAR type representing the class name."; + if (!classArgumentType.is(LogicalTypeFamily.CHARACTER_STRING)) { + throw new ValidationException(errorMessage); + } + + final Optional<String> className = callContext.getArgumentValue(0, String.class); + className.orElseThrow(() -> new ValidationException(errorMessage)); + } + + private static void validateFieldNameInput( + final CallContext callContext, + final int idx, + final LogicalType logicalType, + final Set<String> filedNames) { Review Comment: ```suggestion final Set<String> fieldNames) { ``` -- This is an automated message from the Apache Git Service. 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