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https://issues.apache.org/jira/browse/BEAM-7678?focusedWorklogId=289269&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-289269
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ASF GitHub Bot logged work on BEAM-7678:
----------------------------------------

                Author: ASF GitHub Bot
            Created on: 05/Aug/19 23:56
            Start Date: 05/Aug/19 23:56
    Worklog Time Spent: 10m 
      Work Description: ecanzonieri commented on pull request #9238: 
[BEAM-7678] Fixes bug in output element_type generation in Kv PipelineVisitor
URL: https://github.com/apache/beam/pull/9238#discussion_r310835165
 
 

 ##########
 File path: sdks/python/apache_beam/pipeline.py
 ##########
 @@ -641,8 +641,12 @@ def visit_transform(self, transform_node):
           if len(transform_node.outputs) == 1:
             # The runner often has expectations about the output types as well.
             output, = transform_node.outputs.values()
-            output.element_type = transform_node.transform.infer_output_type(
-                pcoll.element_type)
+            output.element_type = (
 
 Review comment:
   that makes sense.
 
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Issue Time Tracking
-------------------

    Worklog Id:     (was: 289269)
    Time Spent: 40m  (was: 0.5h)

> typehints with_output_types annotation doesn't work for stateful DoFn 
> ----------------------------------------------------------------------
>
>                 Key: BEAM-7678
>                 URL: https://issues.apache.org/jira/browse/BEAM-7678
>             Project: Beam
>          Issue Type: Bug
>          Components: sdk-py-core
>    Affects Versions: 2.13.0
>            Reporter: Enrico Canzonieri
>            Priority: Minor
>          Time Spent: 40m
>  Remaining Estimate: 0h
>
> The output types typehints seem to be ignored when using a stateful DoFn, but 
> the same typehint works perfectly when used without state. This issue 
> prevents a custom Coder from being used because Beam will default to one of 
> theĀ {{FastCoders}} (I believe Pickle).
> Example code:
> {code}
> @typehints.with_output_types(Message)
> class StatefulDoFn(DoFn):
>     COUNTER_STATE = BagStateSpec('counter', VarIntCoder())
>     def process(self, element, counter=DoFn.StateParam(COUNTER_STATE)):
>       (key, messages) = element
>       newMessage = Message()
>       return [newMessage]
> {code}
> The example code is just defining a stateful DoFn for python. The used runner 
> is the Flink 1.6.4 portable runner.
> Finally, overriding {{infer_output_type}} to return a 
> {{typehints.List[Message]}} solves the issue.
> Looking at the code, it seems to me that in 
> [https://github.com/apache/beam/blob/v2.13.0/sdks/python/apache_beam/pipeline.py#L643]
>  we do not take the typehints into account.



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