Dmitry Gusev created TAP5-2576:
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Summary: Copying annotations from interface to proxy causing
problems with type-introspecting libraries like RESTEasy
Key: TAP5-2576
URL: https://issues.apache.org/jira/browse/TAP5-2576
Project: Tapestry 5
Issue Type: Bug
Affects Versions: 5.4.1
Reporter: Dmitry Gusev
If we contribute a tapestry service as a singleton to RESTEasy (how [Tynamo's
tapestry-resteasy integration|https://github.com/tynamo/tapestry-resteasy] is
doing by default) it tries to pick a class (or one of its interfaces) with
{{java.ws.rs.Path}} annotation and uses it as a source for its configuration.
In Tapestry 5.3 the annotation was only attached to an interface, in Tapestry
5.4 proxy class takes precedence here as it also has the annotation.
The problem is tapestry proxy classes are missing generics information and
RESTEasy can't figure out which type it should use when deserialising incoming
parameters.
I.e. if you have a method {{void foo(Collection<Long> ids);}} in your interface
then service proxy class will have erased version of the method, i.e.: {{void
foo(Collection ids)}}.
When RESTEasy tries to deserialise incoming collection its best guess is to use
{{java.lang.Integer}}, because incoming JSON will have numbers. Hence {{ids}}
will be a collection of {{java.lang.Integer}} and if you try to access its
elements as {{Long}} you'll get an error:
{{noformat}}
java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Long
{{noformat}}
I couldn't find any ways how to prevent the annotation copy.
Removing the annotations during class transformation processing would also be
an option, but Tapestry IoC doesn't seem to allow to register custom
{{PlasticClassTransformer}}s for services, which came as a surprise to me,
because you have this option for Tapestry components via
{{ComponentClassTransformWorker2}}.
Ideally would be nice if proxy classes somehow preserve generics information
inherited from implementation/interface classes.
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