On Sep 23, 2009, at 3:51 AM, Jordi Domingo wrote:
> I know what happens with Java :)
>
> What I expected is Jersey check the value before doing the
> conversion and then setting the value to null. Tomorrow i will think
> the best approach to solve this.
>
The value will be null if and only if the parameter is not declared in
the request.
If the parameter is declared then the value of that parameter will be
converted accordingly and errors may result if the value cannot be
converted, and the error is reported back to the client.
What null means is *absence* of the parameter and not absence of a
parameter value.
IIUC what you want is the ability to consider the following cases
semantically equivalent:
1) absence of a parameter; and
2) absence of a parameter value;
There are a number of approaches you can utilize:
1) Use a type of List<Long>, check if there is one or more entries,
and use the first entry if not null.
A null entry value in a list declares that the parameter was
present but the value was absent.
2) Implement is to support a request filter that obtains the form
parameters, removes all parameters that have
empty values, then re-serializes the form contents.
3) Implement support for a StringReaderProvider [1] that supports the
known concrete types that extend Number,
such that an empty String value will return null. This could be
generalized to support the type, say,
ParamValue<T> where the T is deferred to by StringReaderWorkers.
A value of ParamValue<T> that holds
null declared the parameter was present but has no value.
If people think that ParamValue<T> then i can implement support for
that.
Hope this helps,
Paul.
[1]
https://jersey.dev.java.net/nonav/apidocs/1.1.2-ea/jersey/com/sun/jersey/spi/StringReaderProvider.html
[2]
https://jersey.dev.java.net/nonav/apidocs/1.1.2-ea/jersey/com/sun/jersey/spi/StringReaderWorkers.html