Hi Sergey,

thanks for your answer.
I think a good solution could be to pass the ParamConverter a string
containing all the values of a multi-valued query parameter, and let the
user build the collection object.
So, if I have a query string like:
MY_PARAM=VALUE_1&FOO=BAR&MY_PARAM=VALUE_2, the ParamConvert should receive
the string MY_PARAM=VALUE_1&MY_PARAM=VALUE_2, and the user should build the
collection in in the fromString() method. In this way the user can deal
with both the whole collection and its single values.
I also suggest this behaviour should be activated through a property in
order not to break backward compatibility.
What do you think?



2016-10-17 11:47 GMT+02:00 Sergey Beryozkin <sberyoz...@gmail.com>:

> Hi
> Thanks for this query, let me redirect to the CXF users list.
> FYI, CXF JAX-RS runtime prepares a List itself and only expects
> ParamConverters if any to convert individual values.
> I believe RI (Jersey) will also act the same way - but I may be wrong now.
> You can check a "ParamConverter and Collections" thread on the jaxrs users
> list. My understanding there was no any agreement reached.
> Cheers, Sergey
> On 16/10/16 23:48, Diego Ruotolo wrote:
>> Hi everybody,
>> this is my first post to this mailing list.
>> I am using Apache CXF and I have the following problem: I need to read a
>> multiple-value query parameter that is written in a
>> comma-separated-values (CSV) format, hence non standard HTTP way.
>> I know that this will be fixed in versions 3.1.8 and 3.2.0 with the
>> contextual property "parse.query.value.as.collection", as written here:
>> https://issues.apache.org/jira/browse/CXF-6941
>> but the above solution works for ALL query parameters, I want to be
>> selective, for instance I just want query parameters annotated with
>> @MyAnnotation to be parsed as CSV collection, other query parameters may
>> accept commas as a value.
>> Therefore I've written a ParamConverter provided by a
>> ParamConverterProvider: the latter reads the annotation and returns the
>> appriopriate ParamConverter that converts a String into a List. But this
>> is not working since the returned List is used as first element of the
>> linked method parameter, so in the end I have a List of List.
>> Example:
>> Query parameter: MY_PARAM=VALUE_1,VALUE_2,VALUE_3
>> Method parameter: List<?> myParam; // Here I put "?" instead of "String"
>> as generic type in order to explain this example
>> ParamConverter fromString() method: return
>> Arrays.asList(value.split(",")); //returns a List<String>
>> Expected result: myParam is a List<String>, a list of 3 elements
>> (VALUE_1, VALUE_2, VALUE_3)
>> Actual result: myParam is a List<List<String>>, a list with one element,
>> this single element is a list of 3 elements (VALUE_1, VALUE_2, VALUE_3)
>> It seems that when used in conjuction with a List (a Collection?) method
>> parameter, a ParamConverter works per-element, not for the whole list.
>> Is this the correct behaviour? Do you know some work-around that I could
>> use without writing an Apache CXF Interceptor (I don't want to be bound
>> to an implementation of JAX-RS) ?
>> I've noticed that Jersey has a similar issue too:
>> https://java.net/jira/browse/JERSEY-2763
>> Thanks in advice,
>> best regards
> --
> Sergey Beryozkin
> Talend Community Coders
> http://coders.talend.com/

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