验证失败时不会抛出 MethodArgumentNotValidException

Question

我正尝试按照 this 教程在 Spring REST 中实施验证。不过，与教程不同，我的代码在 Koltin 中。

我的代码如下-

实体class

@Entity
class PodcastEntity(@Id @GeneratedValue(strategy = GenerationType.AUTO) @NotNull
                    var id: Long = 0,
                    @field:NotEmpty(message = "Please provide an author")
                    var author: String,
                    @field:NotEmpty(message = "Please provide a title")
                    var title: String,
                    @field:NotEmpty(message = "Please provide a description")
                    var description: String,
                    @field:NotEmpty(message = "Please provide category one")
                    var categoryOne: String,
                    @field:NotEmpty(message = "Please provide category two")
                    var categoryTwo: String,
                    var filePath: String = "")

我的post方法在controller-

中是这样的

@PostMapping("details")
fun addPodcast(@Valid @RequestBody podcastEntity: PodcastEntity) {
    podcastService.addPodcast(podcastEntity)
}

我在postman中的POST请求是这样的-

{
    "author" : "me 3",
    "title" : "File three",
    "description" : "this is a test desc"
}

由于缺少categoryOne和categoryTwo并且我没有自己处理异常，根据教程我的控制台应该显示MethodArgumentNotValidException。但是，我没有得到这样的例外。我得到的是 HttpMessageNotReadableException 异常 -

Resolved [org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Instantiation of [simple type, class com.krtkush.test.entities.PodcastEntity] value failed for JSON property categoryOne due to missing (therefore NULL) value for creator parameter categoryOne which is a non-nullable type; nested exception is com.fasterxml.jackson.module.kotlin.MissingKotlinParameterException: Instantiation of [simple type, class com.krtkush.test.entities.PodcastEntity] value failed for JSON property categoryOne due to missing (therefore NULL) value for creator parameter categoryOne which is a non-nullable type  at [Source: (PushbackInputStream); line: 5, column: 1] (through reference chain: com.krtkush.test.entities.PodcastEntity["categoryOne"])]

我不明白我哪里出错了。请帮忙？

Answer 1

您可以通过提供 HttpMessageNotReadableException 处理程序来处理这个问题然后检查主要原因是否是 MissingKotlinParameterException.

之后，您可以提供自定义验证错误。

    @ExceptionHandler
    override fun handleMessageNotReadableException(
        exception: HttpMessageNotReadableException,
        request: NativeWebRequest
    ): ResponseEntity<Problem> {
        // workaround
        val cause = exception.cause
        if (cause is MissingKotlinParameterException) {
            val violations = setOf(createMissingKotlinParameterViolation(cause))
            return newConstraintViolationProblem(exception, violations, request)
        }
        return create(Status.BAD_REQUEST, UnableToReadInputMessageProblem(), request)
    }

    private fun createMissingKotlinParameterViolation(cause: MissingKotlinParameterException): Violation {
        val name = cause.path.fold("") { jsonPath, ref ->
            val suffix = when {
                ref.index > -1 -> "[${ref.index}]"
                else -> ".${ref.fieldName}"
            }
            (jsonPath + suffix).removePrefix(".")
        }
        return Violation(name, "must not be null")
    }

通过这种方式，您可以获得具有适当约束错误的良好输出。

您可以尝试直接为 MissingKotlinParameterException 声明 @ExceptionHandler。

根据问题回答

Answer 2

根据 Damian 的 SO link 在他的回答中，我发现第一个答案确实很有帮助而且更合适。我修改了@Entitiy class，使所需的字段可以为空（?），就像这样-

@Entity
class PodcastEntity(@Id @GeneratedValue(strategy = GenerationType.AUTO)
                    var id: Long = 0,
                    @field:NotEmpty(message = "Please provide an author")
                    var author: String?,
                    @field:NotEmpty(message = "Please provide a title")
                    var title: String?,
                    @field:NotEmpty(message = "Please provide a description")
                    var description: String?,
                    @field:NotEmpty(message = "Please provide category one")
                    var categoryOne: String?,
                    @field:NotEmpty(message = "Please provide category two")
                    var categoryTwo: String?,
                    var filePath: String = "")

这确保代码在所有三种情况下都抛出 MethodArgumentNotValidException - 1. 空参数 2. null 参数 3. 缺少参数

验证失败时不会抛出 MethodArgumentNotValidException

MethodArgumentNotValidException not thrown in case of validation fail

spring

spring-validator

spring-boot

spring-rest