[
https://issues.apache.org/jira/browse/BEAM-3530?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Kenneth Knowles updated BEAM-3530:
----------------------------------
This Jira ticket has a pull request attached to it, but is still open. Did the
pull request resolve the issue? If so, could you please mark it resolved? This
will help the project have a clear view of its open issues.
> DoFn.process should raise exception if something other than a List is returned
> ------------------------------------------------------------------------------
>
> Key: BEAM-3530
> URL: https://issues.apache.org/jira/browse/BEAM-3530
> Project: Beam
> Issue Type: Improvement
> Components: sdk-py-core
> Reporter: Chuan Yu Foo
> Priority: P3
> Labels: starter
>
> The process method of DoFns can either return values or yield values. In the
> case of returning values, it expects a List of elements to be returned. When
> returning a single value, it is easy to forget this, and return the value
> instead.
> Correct way:
> {{class SomeDoFn(beam.DoFn)}}
> {{ def process(self, elem):}}
> {{ return ['a']}}
> Incorrect way:
> {{class SomeDoFn(beam.DoFn)}}
> {{ def process(self, elem):}}
> {{ return 'a'}}
> A pipeline with the incorrect DoFn will fail will a cryptic error message
> without a direct indication that the actual error is due to SomeDoFn
> returning an element instead of a List containing that element. This issue is
> very time-consuming to track down.
> It would be good if the pipeline could raise an exception or otherwise
> indicate that the DoFn is incorrectly returning an element instead of a List
> to make it easier to identify the error.
--
This message was sent by Atlassian Jira
(v8.20.1#820001)
