ahmedabu98 commented on code in PR #32367: URL: https://github.com/apache/beam/pull/32367#discussion_r1760318971
########## sdks/java/core/src/main/java/org/apache/beam/sdk/util/RowStringInterpolator.java: ########## @@ -0,0 +1,181 @@ +/* + * 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.sdk.util; + +import java.io.Serializable; +import java.util.HashSet; +import java.util.List; +import java.util.Set; +import java.util.regex.Matcher; +import java.util.regex.Pattern; +import java.util.stream.Collectors; +import org.apache.beam.sdk.schemas.Schema; +import org.apache.beam.sdk.transforms.windowing.BoundedWindow; +import org.apache.beam.sdk.transforms.windowing.PaneInfo; +import org.apache.beam.sdk.values.Row; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.MoreObjects; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Splitter; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Sets; +import org.apache.commons.lang3.StringUtils; +import org.checkerframework.checker.nullness.qual.Nullable; +import org.joda.time.Instant; + +/** + * A utility that interpolates values in a pre-determined {@link String} using an input Beam {@link + * Row}. + * + * <p>The {@link RowStringInterpolator} looks for field names specified inside {curly braces}. For + * example, if the interpolator is configured with the String {@code "unified {foo} and streaming"}, + * it will look for a field name {@code "foo"} in the input {@link Row} and substitute in that + * value. If a {@link RowStringInterpolator} is configured with a template String that contains no + * placeholders (i.e. no curly braces), it will simply return that String, untouched. + * + * <p>Nested fields can be specified using dot-notation (e.g. {@code "top.middle.nested"}). + * + * <p>Configure a {@link RowStringInterpolator} like so: + * + * <pre>{@code + * String template = "unified {foo} and {bar.baz}!"; + * Row inputRow = {foo: "batch", bar: {baz: "streaming"}, ...}; + * + * RowStringInterpolator interpolator = new RowStringInterpolator(template, beamSchema); + * String output = interpolator.interpolate(inputRow); + * // output --> "unified batch and streaming!" + * }</pre> + * + * <p>Additionally, {@link #interpolate(Row, BoundedWindow, PaneInfo, Instant)} can be used in + * streaming scenarios to substitute windowing metadata into the template String. To make use of + * this, use the relevant placeholder: + * + * <ul> + * <li>$WINDOW: the window's string representation + * <li>$PANE_INDEX: the pane's index + * <li>$YYYY: the element timestamp's year + * <li>$MM: the element timestamp's month + * <li>$DD: the element timestamp's day + * </ul> + * + * <p>For example, your Sting template can look like: + * + * <pre>{@code "unified {foo} and {bar} since {$YYYY}-{$MM}!"}</pre> + */ +public class RowStringInterpolator implements Serializable { + private final String template; + private final Set<String> fieldsToReplace; + public static final String WINDOW = "$WINDOW"; + public static final String PANE_INDEX = "$PANE_INDEX"; + public static final String YYYY = "$YYYY"; + public static final String MM = "$MM"; + public static final String DD = "$DD"; + private static final Set<String> WINDOWING_METADATA = + Sets.newHashSet(WINDOW, PANE_INDEX, YYYY, MM, DD); + + public RowStringInterpolator(String template, Schema rowSchema) { + this.template = template; + + Matcher m = Pattern.compile("\\{(.+?)}").matcher(template); Review Comment: Thanks, done -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
