[jira] Created: (JDO-633) List.get(int) support in JDOQL is missing

List.get(int) support in JDOQL is missing
-----------------------------------------

                 Key: JDO-633
                 URL: https://issues.apache.org/jira/browse/JDO-633
             Project: JDO
          Issue Type: New Feature
            Reporter: Timo Westkämper


It would be nice to get List.get(int) into JDOQL, in other words access of indexed list elements.

Querydsl has support for that and for consistency it would be nice if JDOQL supported it as well.

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Timo Westkämper updated JDO-633:
--------------------------------

    Component/s: query2

> List.get(int) support in JDOQL is missing
> -----------------------------------------
>
>                 Key: JDO-633
>                 URL: https://issues.apache.org/jira/browse/JDO-633
>             Project: JDO
>          Issue Type: New Feature
>          Components: query2
>            Reporter: Timo Westkämper
>
> It would be nice to get List.get(int) into JDOQL, in other words access of indexed list elements.
> Querydsl has support for that and for consistency it would be nice if JDOQL supported it as well.

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     [ https://issues.apache.org/jira/browse/JDO-633?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Michael Bouschen updated JDO-633:
---------------------------------

          Component/s: specification
    Affects Version/s: JDO 2 maintenance release 2

> List.get(int) support in JDOQL is missing
> -----------------------------------------
>
>                 Key: JDO-633
>                 URL: https://issues.apache.org/jira/browse/JDO-633
>             Project: JDO
>          Issue Type: New Feature
>          Components: query2, specification
>    Affects Versions: JDO 2 maintenance release 2
>            Reporter: Timo Westkämper
>
> It would be nice to get List.get(int) into JDOQL, in other words access of indexed list elements.
> Querydsl has support for that and for consistency it would be nice if JDOQL supported it as well.

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     [ https://issues.apache.org/jira/browse/JDO-633?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Michael Bouschen updated JDO-633:
---------------------------------

    Component/s:     (was: query2)
                 tck2

> List.get(int) support in JDOQL is missing
> -----------------------------------------
>
>                 Key: JDO-633
>                 URL: https://issues.apache.org/jira/browse/JDO-633
>             Project: JDO
>          Issue Type: New Feature
>          Components: specification, tck2
>    Affects Versions: JDO 2 maintenance release 2
>            Reporter: Timo Westkämper
>
> It would be nice to get List.get(int) into JDOQL, in other words access of indexed list elements.
> Querydsl has support for that and for consistency it would be nice if JDOQL supported it as well.

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    [ https://issues.apache.org/jira/browse/JDO-633?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12724602#action_12724602 ]

Craig Russell commented on JDO-633:
-----------------------------------

Andy commented:

A List has an order (whether it is an "indexed" List, or
an "ordered" List (using JPA-style ordering criteria)). The user puts items
in the List and persists the List. The user then wants to grab element at
index 2. Storing the order in the datastore, in some way, is essential to
support (indexed) Lists, hence querying should be straightforward. Since JDO
doesn't define an ordering constraint, it is reasonable to assume that in JDO
a List is an "indexed" List, hence retains the users ordering.

As far as testing goes, surely all you need to do is persist an object with a
List with some elements in some order, and then do a query, assuming the same
order as they had at the moment of persistence. Where does DB-specific SQL
come into this ? surely that is the problem for the implementation.

> List.get(int) support in JDOQL is missing
> -----------------------------------------
>
>                 Key: JDO-633
>                 URL: https://issues.apache.org/jira/browse/JDO-633
>             Project: JDO
>          Issue Type: New Feature
>          Components: specification, tck2
>    Affects Versions: JDO 2 maintenance release 2
>            Reporter: Timo Westkämper
>
> It would be nice to get List.get(int) into JDOQL, in other words access of indexed list elements.
> Querydsl has support for that and for consistency it would be nice if JDOQL supported it as well.

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Craig Russell commented on JDO-633:
-----------------------------------

The specification update is trivial. The RI sounds straightforward. Interim to being part of the required query methods, perhaps Timo and Andy can collaborate on seeing how to make this work?

> List.get(int) support in JDOQL is missing
> -----------------------------------------
>
>                 Key: JDO-633
>                 URL: https://issues.apache.org/jira/browse/JDO-633
>             Project: JDO
>          Issue Type: New Feature
>          Components: specification, tck2
>    Affects Versions: JDO 2 maintenance release 2
>            Reporter: Timo Westkämper
>
> It would be nice to get List.get(int) into JDOQL, in other words access of indexed list elements.
> Querydsl has support for that and for consistency it would be nice if JDOQL supported it as well.

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Andy Jefferson commented on JDO-633:
------------------------------------

DataNucleus query language="JDOQL2" (a replacement for the JDOQL implementation that we've used since day 1, for RDBMS datastores) now has support for List.get(int). Set persistence property "datanucleus.query.JDOQL.implementation" to be "JDOQL2" and it will use this implementation.

In-memory evaluation of JDOQL also has support for List.get(int).

> List.get(int) support in JDOQL is missing
> -----------------------------------------
>
>                 Key: JDO-633
>                 URL: https://issues.apache.org/jira/browse/JDO-633
>             Project: JDO
>          Issue Type: New Feature
>          Components: specification, tck2
>    Affects Versions: JDO 2 maintenance release 2
>            Reporter: Timo Westkämper
>
> It would be nice to get List.get(int) into JDOQL, in other words access of indexed list elements.
> Querydsl has support for that and for consistency it would be nice if JDOQL supported it as well.

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