Helidon 4.0.7: Parameters.first(String) generates java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0 about helidon

[talios]

I hit something similar to this the other day and worked around it with:

var query = req.query();
if (!query.isEmpty() && query.get("period") instanceof String period) {

Having to check the isEmpty is kind-of a pain. Tho the out-of-bounds you got seems worse.

[hrstoyanov]

@talios have you tried:

var period = req.query().first("period").asString().orElse("whatever);

//or

req
    .query()
    .first("period")
    .asString()
    .ifPresent(period->{....});

[talios]

@hrstoyanov That works nicely - even better using .as(Period::parse) to map to the desired type. Much cleaner - cheers!

[tomas-langer]

Reason for this bug is that the implementation did not expect an empty list as a value in the map used to create it.
The place we introduced this (I think the only one) is in URI Query, where we handle the case of a parameter without a follow-up = as a name without a value - so contains returns true, but there is no value.
So we were missing a validation of the map for the assumption of the implementation, and a change once we decided to support it.
The only sloppiness I see here is the lack of test for a query parameter without a value...

[hrstoyanov]

@tomas-langer apologies, the code is actaully very nicely designed maybe needs unit test, I updated the initial report. Sorry!

[jbescos]

Merged, thank you for reporting it