robertwb commented on a change in pull request #13215: URL: https://github.com/apache/beam/pull/13215#discussion_r524491784
########## File path: sdks/java/harness/src/main/java/org/apache/beam/fn/harness/ToStringFnRunner.java ########## @@ -0,0 +1,76 @@ +/* + * 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.beam.fn.harness; + +import com.google.auto.service.AutoService; +import java.util.Map; +import org.apache.beam.model.pipeline.v1.RunnerApi.PTransform; +import org.apache.beam.runners.core.construction.PTransformTranslation; +import org.apache.beam.sdk.function.ThrowingFunction; +import org.apache.beam.sdk.values.KV; +import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.ImmutableMap; + +/** + * Translates from elements to human-readable string. + * + * <p>Translation function: + * + * <ul> + * <li>Input: {@code KV<nonce, element>} + * <li>Output: {@code KV<nonce, string>} + * </ul> + * + * <p>For each element, the human-readable string is returned. The nonce is used by a runner to + * associate each input with its output. The nonce is represented as an opaque set of bytes. + */ +@SuppressWarnings({ Review comment: Can you scope this more narrowly, or use <Object> instead? ########## File path: sdks/java/harness/src/main/java/org/apache/beam/fn/harness/ToStringFnRunner.java ########## @@ -0,0 +1,76 @@ +/* + * 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.beam.fn.harness; + +import com.google.auto.service.AutoService; +import java.util.Map; +import org.apache.beam.model.pipeline.v1.RunnerApi.PTransform; +import org.apache.beam.runners.core.construction.PTransformTranslation; +import org.apache.beam.sdk.function.ThrowingFunction; +import org.apache.beam.sdk.values.KV; +import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.ImmutableMap; + +/** + * Translates from elements to human-readable string. + * + * <p>Translation function: + * + * <ul> + * <li>Input: {@code KV<nonce, element>} + * <li>Output: {@code KV<nonce, string>} + * </ul> + * + * <p>For each element, the human-readable string is returned. The nonce is used by a runner to + * associate each input with its output. The nonce is represented as an opaque set of bytes. + */ +@SuppressWarnings({ + "rawtypes" // TODO(https://issues.apache.org/jira/browse/BEAM-10556) +}) +public class ToStringFnRunner { + static final String URN = PTransformTranslation.TO_STRING_TRANSFORM_URN; + + /** + * A registrar which provides a factory to handle translating elements to a human readable string. + */ + @AutoService(PTransformRunnerFactory.Registrar.class) + public static class Registrar implements PTransformRunnerFactory.Registrar { + + @Override + public Map<String, PTransformRunnerFactory> getPTransformRunnerFactories() { + return ImmutableMap.of( + URN, + MapFnRunners.forValueMapFnFactory(ToStringFnRunner::createToStringFunctionForPTransform)); + } + } + + static <T, V> ThrowingFunction<KV<T, V>, KV<T, String>> createToStringFunctionForPTransform( + String ptransformId, PTransform pTransform) { + return (KV<T, V> input) -> { + String val = "null"; Review comment: Rather than assigning a value and then overwriting it, do if (v == null) { val = "null"; } else { val = v.toString(); } You could also just return "" + val or, even better, just use Objects.toString(input.getValue()). ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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