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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Work logged] (BEAM-4076) Schema followups
Date Fri, 13 Jul 2018 22:21:00 GMT

     [ 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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