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https://issues.apache.org/jira/browse/BEAM-2640?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16093588#comment-16093588
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Eugene Kirpichov commented on BEAM-2640:
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Coder inference for this is complicated by the fact that ValueProvider does not
expose a TypeDescriptor for the value being provided. Even though it could. I'm
gonna start with requiring to explicitly provide a coder.
> Introduce Create.ofProvider(ValueProvider)
> ------------------------------------------
>
> Key: BEAM-2640
> URL: https://issues.apache.org/jira/browse/BEAM-2640
> Project: Beam
> Issue Type: New Feature
> Components: sdk-java-core
> Reporter: Eugene Kirpichov
> Assignee: Eugene Kirpichov
>
> When you have a ValueProvider<T> that may or may not be accessible at
> construction time, a common task is to wrap it into a single-element
> PCollection<T>. This is especially common when migrating an IO connector that
> used something like Create.of(query) followed by a ParDo, to having query be
> a ValueProvider.
> Currently this is done in an icky way (e.g.
> https://github.com/apache/beam/blob/master/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/datastore/DatastoreV1.java#L615)
> We should have a convenience helper for that.
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