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https://issues.apache.org/jira/browse/SLING-6637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15938257#comment-15938257
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Konrad Windszus edited comment on SLING-6637 at 3/23/17 1:11 PM:
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Non existing properties used in EL don't throw exceptions because
a) that is explicitly defined like this for HTL EL
b) is in line with JSP EL
Also this is one of the fundamental differences between EL and block statements.
If we wouldn't throw an explicit exception for {{data-sly-use}} then a a
developer's typo like {{data-sly-use.logo=org.apache.slign.MyModel}} would be
much harder to detect, because the HTL rendering would continue and you just
would get back the empty result for every operation on {{logo}}.
was (Author: kwin):
Non existing properties used in EL don't throw exceptions because
a) that is explicitly defined for HTL EL
b) is in line with JSP EL
Also this is one of the fundamental differences between EL and block statements.
If we wouldn't throw an explicit exception for {{data-sly-use}} then a a
developer's typo like {{data-sly-use.logo=org.apache.slign.MyModel}} would be
much harder to detect, because the HTL rendering would continue and you just
would get back the empty result for every operation on {{logo}}.
> [htl] data-sly-use should not raise an exception when resource doesn't exist
> ----------------------------------------------------------------------------
>
> Key: SLING-6637
> URL: https://issues.apache.org/jira/browse/SLING-6637
> Project: Sling
> Issue Type: Bug
> Components: Scripting
> Reporter: Feike Visser
> Assignee: Radu Cotescu
>
> Following code:
> {code}
> <sly data-sly-use.x="${ 'x/y/z' }"/>
> {code}
> You get now the following exception:
> {code}
> org.apache.sling.scripting.sightly.SightlyException: No use provider could
> resolve identifier x/y/z
> {code}
> In practice you want to have a null-value assigned to x, now developers will
> make a lot of checks to make sure the resource does exist.
> In addition we can log warning message when this happens.
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