[OASIS Issue Tracker] (ODATA-9) allow expressions in the $select query option

[OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>]

    [ https://issues.oasis-open.org/browse/ODATA-9?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=59652#comment-59652 ] 

Ralf Handl commented on ODATA-9:
--------------------------------

Adding a calculated field without aggregating the result can be achieved via $apply:

GET Products?$apply=groupby((<key properties, other properties to include in projection>),aggregate(<expr> as <propertyname>, ...))

Having to list all properties desired in the selection plus the key properties is a bit clumsy, so a shortcut syntax would be convenient, e.g.

GET Products?$calculate=<expr> as <propertyname>, ...

Instead of a new system query option this could also be done as a new set transformation for $apply:

GET Products?$apply=calculate(<expr> as <propertyname>, ...)

The "calculate" transformation would keep all properties and items of the input set and just add the calculated fields to each item. This form could already be specified with a new CSD of the Extension for Data Aggregation.

> allow expressions in the $select query option
> ---------------------------------------------
>
>                 Key: ODATA-9
>                 URL: https://issues.oasis-open.org/browse/ODATA-9
>             Project: OASIS Open Data Protocol (OData) TC
>          Issue Type: Improvement
>          Components: OData Protocol, OData URL Conventions
>    Affects Versions: V4.0_WD01
>         Environment: [Proposed]
>            Reporter: Andrew Eisenberg
>              Labels: GoodIdea, Usability
>             Fix For: V4.1_WD01
>
>
> OData could be extended to allow expressions in the $select query option, allowing derived values to be returned along with the properties of an entity.
> This could be expressed as:
> http://odata.netflix.com/v2/Catalog/Titles?$select=Name,substring(ShortSynopsis,20) as Summary
> or
> http://odata.netflix.com/v2/Catalog/Titles?$select=Name&$extendedSelect=substring(ShortSynopsis,20) as Summary



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