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Date: Thu, 29 Sep 2016 15:29:20 +0000 (UTC)
From: =?utf-8?Q?Jean-Baptiste_Onofr=C3=A9_=28JIRA=29?= <jira@apache.org>
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Subject: [jira] [Commented] (BEAM-621) Add MapValues and MapKeys functions
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archived-at: Thu, 29 Sep 2016 15:29:25 -0000


    [ https://issues.apache.org/jira/browse/BEAM-621?page=3Dcom.atlassian.j=
ira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D155330=
88#comment-15533088 ]=20

Jean-Baptiste Onofr=C3=A9 commented on BEAM-621:
-------------------------------------------

About the same idea, it would be great to have {{MapElements}} working with=
 POJO. For instance if the {{PCollection}} contains POJO like:

{code}
class MyPojo implements Serializable {
  ...
  public String getName() { ...=C2=A0}
  public Integer getAge() { ... }
}
{code}

today, to map this POJO to just name, we have to use {{MapElements}} with a=
 function. It could be interesting to provide a convenient function like {{=
MapElements.with("name"))}} that will use reflection to map on {{getName()}=
}.

> Add MapValues and MapKeys functions
> -----------------------------------
>
>                 Key: BEAM-621
>                 URL: https://issues.apache.org/jira/browse/BEAM-621
>             Project: Beam
>          Issue Type: New Feature
>          Components: beam-model
>            Reporter: Jean-Baptiste Onofr=C3=A9
>            Assignee: Jean-Baptiste Onofr=C3=A9
>
> Currently, we have the {{MapElements}} {{PTransform}} that "convert" a {{=
PCollection}} of {{KV}} to another {{PCollection}} (for instance {{String}}=
).
> A very classic mapping function is to just have the keys or values of {{K=
V}}.
> To do it currently, we can use {{MapElements}} or a generic {{ParDo}} (wi=
th {{DoFn}}).
> It would be helpful and reduce the user code to have {{MapValues}} and {{=
MapKeys}}. It would take a {{PCollection}}=C2=A0of {{KV}}: {{MapKeys}} will=
 map the=C2=A0input {{PCollection}}=C2=A0to a {{PCollection}} of {{K}} and =
{{MapValues}} to a {{PCollection}} of {{V}}.


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