PROBLEM

Given the following controller …

@RestController
@RequestMapping(value = '/controller')
class MyController {

    @RequestMapping(method = RequestMethod.GET)
    ResponseEntity main(@RequestParam(name = 'dateTime') LocalDateTime dateTime) {
        // ...

        return ResponseEntity.noContent().build()
    }
}

When executing …

GET https://localhost:8443/controller?dateTime=2017-06-22T17:38

… the web service call returns 400 Bad Request with the following error in the console log:-

Failed to bind request element: org.springframework.web.method.annotation.MethodArgumentTypeMismatchException: 
Failed to convert value of type 'java.lang.String' to required type 'java.time.LocalDateTime'; nested exception 
is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] 
to type [@org.springframework.web.bind.annotation.RequestParam java.time.LocalDateTime] for value '2017-06-22T17:38'; 
nested exception is java.lang.IllegalArgumentException: Parse attempt failed for value [2017-06-22T17:38]

SOLUTION

One solution is to change the data type from java.time.LocalDateTime to java.lang.String before parsing it to java.time.LocalDateTime. However, it is a little more verbose than I like.

A better way is to leverage @DateTimeFormat:-

@RestController
@RequestMapping(value = '/controller')
class MyController {

    @RequestMapping(method = RequestMethod.GET)
    ResponseEntity main(@RequestParam(name = 'dateTime') @DateTimeFormat(pattern = "yyyy-MM-dd'T'HH:mm") LocalDateTime dateTime) {
        // ...

        return ResponseEntity.noContent().build()
    }
}