Java JAX-RS @DefaultValue用于列表

Question

I have a List of enum values as a query parameter. I want to have a @DefaultValue (single value). Is it possible to have an empty list as actual parameter to overwrite this default value?

The reason for this question is that Swagger (2.0) shows a list of the enum string values and an additional first entry -- . I can select any number of entries, including the empty set. So the -- entry seems to make no much sense. But selecting nothing or the -- entry results in 2 different request URLs, one without the parameter and one with the parameter with empty value.

So my expectation was that the request without the parameter results in an list with the default value on service side (as it actually is). And I expected an empty list in the other case, so that I would have a way to overwrite the default value also with an empty list. But that seems not the case.

I also expected that the default value would be pre-selected in the Swagger UI list, which is also not the case.

So the answer to my first question seems to be no .

So the second question is: What is the reason or use of the -- entry in the list in Swagger UI?

Answer 1

For problem number 1 you can try something like this:

@GET
public Response getList(@QueryParam("enumList") @DefaultValue("#{T(java.util.Collections).emptyList()}") List<EnumType> enumList) {

}