[jira] [Commented] (TINKERPOP-2314) Employ by(String) for Map when possible and improve errors around incorrect types

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TINKERPOP-2314?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16973659#comment-16973659 ] 

ASF GitHub Bot commented on TINKERPOP-2314:
-------------------------------------------

spmallette commented on pull request #1223: TINKERPOP-2314 Employ by(String) for Map when possible
URL: https://github.com/apache/tinkerpop/pull/1223
 
 
   https://issues.apache.org/jira/browse/TINKERPOP-2314
   
   Also improve errors around incorrect types that might be called using this modulator overload. See upgrade docs for reasoning and examples of what's happening here.
   
   All tests pass with `docker/build.sh -t -n -i`
   
   VOTE +1
 
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> Employ by(String) for Map when possible and improve errors around incorrect types
> ---------------------------------------------------------------------------------
>
>                 Key: TINKERPOP-2314
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-2314
>             Project: TinkerPop
>          Issue Type: Improvement
>          Components: process
>    Affects Versions: 3.3.9
>            Reporter: Stephen Mallette
>            Assignee: Stephen Mallette
>            Priority: Major
>
> This bit of Gremlin demonstrates both problems for uses of {{by(String)}}:
> {code}
> gremlin> g.V().valueMap().project('x').by('name')
> java.util.LinkedHashMap cannot be cast to org.apache.tinkerpop.gremlin.structure.Element
> Type ':help' or ':h' for help.
> Display stack trace? [yN]n
> {code}
> First, users typically expect this to work because they figure they are just grabbing a keys value from a {{Map}} and then get the difficult to understand message which doesn't tell you how to resolve. As a side note, the way to resolve is with:
> {code}
> gremlin> g.V().valueMap().project('x').by(select('name'))
> ==>[x:[marko]]
> ==>[x:[stephen]]
> ==>[x:[matthias]]
> ==>[x:[daniel]]
> ==>[x:[gremlin]]
> ==>[x:[tinkergraph]]
> {code}



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