Spring Webflux：仍然需要可选的RequestPart / RequestParam吗？

Question

I'm trying to use optional request parameters / request parts, but when I don't provide an optional parameter, my request just hangs indenfinitely.

@RestController
@RequestMapping("/service")
class MyController {
    @PostMapping
    fun print(@RequestPart("name", required = false) name: String) {
        if (name != null)
            print(name)
        else
            print("grr")
    }
}

If I provide the parameter name in my request, it no longer hangs definitely in postman, the request goes through. But I expected it to go through anyway when I don't provide the parameter name and print "grr".

This required property not working properly (at least in my mind) is validated when you add another supposedly optional property.

@RestController
@RequestMapping("/service")
class MyController {
    @PostMapping
    fun print(@RequestPart("name", required = false) name: String,
              @RequestPart("friend_name", required = false) friendsName: String) {
        if (name != null)
            print(name)
        else
            print("grr")
    }
}

Now when I provide the parameter name but not friend_name , it says the value cannot be null.

{
    "timestamp": "2018-10-10T09:50:49.305+0000",
    "path": "/service",
    "status": 500,
    "error": "Internal Server Error",
    "message": "Parameter specified as non-null is null: method co.example.controllers.MyController.print, parameter friendsName"
}

I have tried the same for @RequestParam and @RequestPart with the same results.

Answer 1

Mark your optional parameters as nullable. Therefore:

@RequestPart("name", required = false) name: String?
@RequestPart("friend_name", required = false) friendsName: String?