Support Kotlin parameter default values in HTTP handler methods [SPR-16598]

[spring-issuemaster]

Take Weiland opened SPR-16598 and commented

Support specifying defaults for e.g. @RequestMapping via Kotlin parameter default values like so:

@GetMapping
fun get(@RequestParam limit: Int = 20)

Such a method should behave equivalent to @RequestMapping with defaultValue, except that the value does not need to be processed by converters, etc.

This can be implemented in org.springframework.web.method.support.InvocableHandlerMethod using Kotlin Reflection (KCallable#callBy), which allows omitting parameters with default values.

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Affects: 5.0.4

Referenced from: pull request #1741

2 votes, 5 watchers

[spring-issuemaster]

Alex Rader commented

In Kotlin @RequestBody required=false when use default arguments
spring-projects/spring-boot#12691

[spring-issuemaster]

Sébastien Deleuze commented

As discussed in the PR, current Kotlin API force us to integrate that as a rather involved and not very elegant way, I will raise and discuss that point with Kotlin team. As a consequence, I think it is more reasonable to target 5.2 for that one.