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https://issues.apache.org/jira/browse/BEAM-4076?focusedWorklogId=123070&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-123070
]
ASF GitHub Bot logged work on BEAM-4076:
----------------------------------------
Author: ASF GitHub Bot
Created on: 13/Jul/18 22:20
Start Date: 13/Jul/18 22:20
Worklog Time Spent: 10m
Work Description: reuvenlax commented on a change in pull request #5941:
[BEAM-4076] Schema utilities for converting between types
URL: https://github.com/apache/beam/pull/5941#discussion_r202486286
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/transforms/Convert.java
##########
@@ -0,0 +1,162 @@
+/*
+ * 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.schemas.transforms;
+
+import javax.annotation.Nullable;
+import org.apache.beam.sdk.annotations.Experimental;
+import org.apache.beam.sdk.annotations.Experimental.Kind;
+import org.apache.beam.sdk.schemas.NoSuchSchemaException;
+import org.apache.beam.sdk.schemas.SchemaCoder;
+import org.apache.beam.sdk.schemas.SchemaRegistry;
+import org.apache.beam.sdk.transforms.DoFn;
+import org.apache.beam.sdk.transforms.PTransform;
+import org.apache.beam.sdk.transforms.ParDo;
+import org.apache.beam.sdk.transforms.SerializableFunctions;
+import org.apache.beam.sdk.values.PCollection;
+import org.apache.beam.sdk.values.Row;
+import org.apache.beam.sdk.values.TypeDescriptor;
+
+/** A set of utilities for converting between different objects supporting
schemas. */
+@Experimental(Kind.SCHEMAS)
+public class Convert {
+ /**
+ * Convert a {@link PCollection<InputT>} into a {@link PCollection<Row>}.
+ *
+ * <p>The input {@link PCollection} must have a schema attached. The output
collection will have
+ * the same schema as the iput.
+ */
+ public static <InputT> PTransform<PCollection<InputT>, PCollection<Row>>
toRows() {
+ return to(Row.class);
+ }
+
+ /**
+ * Convert a {@link PCollection<Row>} into a {@link PCollection<OutputT>}.
+ *
+ * <p>The output schema will be inferred using the schema registry. A schema
must be registered
+ * for this type, or the conversion will fail.
+ */
+ public static <OutputT> PTransform<PCollection<Row>, PCollection<OutputT>>
fromRows(
+ Class<OutputT> clazz) {
+ return to(clazz);
+ }
+
+ /**
+ * Convert a {@link PCollection<Row>} into a {@link PCollection<OutputT>}.
+ *
+ * <p>The output schema will be inferred using the schema registry. A schema
must be registered
+ * for this type, or the conversion will fail.
+ */
+ public static <OutputT> PTransform<PCollection<Row>, PCollection<OutputT>>
fromRows(
+ TypeDescriptor<OutputT> typeDescriptor) {
+ return to(typeDescriptor);
+ }
+
+ /**
+ * Convert a {@link PCollection<InputT>} to a {@link PCollection<OutputT>}.
+ *
+ * <p>This function allows converting between two types as long as the two
types have
+ * <i>compatible</i> schemas. Two schemas are said to be <i>compatible</i>
if they recursively
+ * have fields with the same names, but possibly different orders.
+ */
+ public static <InputT, OutputT> PTransform<PCollection<InputT>,
PCollection<OutputT>> to(
+ Class<OutputT> clazz) {
+ return to(TypeDescriptor.of(clazz));
+ }
+
+ /**
+ * Convert a {@link PCollection<InputT>} to a {@link PCollection<OutputT>}.
+ *
+ * <p>This function allows converting between two types as long as the two
types have
+ * <i>compatible</i> schemas. Two schemas are said to be <i>compatible</i>
if they recursively
+ * have fields with the same names, but possibly different orders.
+ */
+ public static <InputT, OutputT> PTransform<PCollection<InputT>,
PCollection<OutputT>> to(
+ TypeDescriptor<OutputT> typeDescriptor) {
+ return new ConvertTransform<>(typeDescriptor);
+ }
+
+ private static class ConvertTransform<InputT, OutputT>
+ extends PTransform<PCollection<InputT>, PCollection<OutputT>> {
+ @Nullable TypeDescriptor<OutputT> outputTypeDescriptor = null;
Review comment:
Fine to change for now. In the future, might have to make this nullable
though.
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Issue Time Tracking
-------------------
Worklog Id: (was: 123070)
Time Spent: 10h 20m (was: 10h 10m)
> Schema followups
> ----------------
>
> Key: BEAM-4076
> URL: https://issues.apache.org/jira/browse/BEAM-4076
> Project: Beam
> Issue Type: Improvement
> Components: beam-model, dsl-sql, sdk-java-core
> Reporter: Kenneth Knowles
> Priority: Major
> Time Spent: 10h 20m
> Remaining Estimate: 0h
>
> This umbrella bug contains subtasks with followups for Beam schemas, which
> were moved from SQL to the core Java SDK and made to be type-name-based
> rather than coder based.
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