在 Ktor 中验证请求

Question

我有一个使用 Ktor 制作的 API，当请求的 som 字段失败时，它返回 500 错误，我想检查所有请求数据并返回，在本例中为 422。

请求类：

@Serializable
data class LoginRequest (
    val email: String,
    val password: String
)

路由

route("v1/auth/login") {
    post {
        val loginRequest = call.receive<LoginRequest>()
        //LOGIN METHOD
    }
}

现在Ktor显示的错误是：

[eventLoopGroupProxy-4-1] ERROR Application - Unhandled: POST - /v1/auth/login
kotlinx.serialization.MissingFieldException: Field 'password' is required for type with serial name

确保系统不会失败并以 BadRequest 响应的最佳方法是什么？

Answer 1

如果你想在特定的地方捕获异常，你可以使用try/catch:

try {
    val loginRequest = call.receive<LoginRequest>()
    ...
} catch (e: SerializationException) {
    // serialization exceptions
    call.respond(HttpStatusCode.UnprocessableEntity)
} catch (t: Throwable) {
    // other exceptions
    call.respond(HttpStatusCode.InternalServerError)
}

如果你想要一些全局的try/catch，Ktor 有StatusPages 功能来处理这种情况：它会在调用处理过程中捕获所有异常。

与try/catch 相同，您可以捕获特定异常，例如SerializationException，或使用Exception/Throwable 处理任何其他异常。

install(StatusPages) {
    exception<SerializationException> { cause ->
        // serialization exceptions
        call.respond(HttpStatusCode.UnprocessableEntity)
    }
    exception<Throwable> { cause ->
        // other exceptions
        call.respond(HttpStatusCode.InternalServerError)
    }
}

Answer 2

您可以使用默认的null 值使字段可为空，在遇到未知属性时忽略错误并手动验证结果对象。这是一个例子：

import io.ktor.application.*
import io.ktor.features.*
import io.ktor.http.*
import io.ktor.request.*
import io.ktor.response.*
import io.ktor.routing.*
import io.ktor.serialization.*
import io.ktor.server.engine.*
import io.ktor.server.netty.*
import kotlinx.serialization.Serializable
import kotlinx.serialization.json.Json

@Serializable
data class LoginRequest (
    val email: String? = null,
    val password: String? = null
)

suspend fun main() {
    embeddedServer(Netty, port = 8080) {
        install(ContentNegotiation) {
            json(Json {
                ignoreUnknownKeys = true
            })
        }

        routing {
            post("/") {
                val request = call.receive<LoginRequest>()

                if (request.email == null || request.password == null) {
                    call.respond(HttpStatusCode.UnprocessableEntity)
                    return@post
                }

                call.respond(HttpStatusCode.OK)
            }
        }
    }.start()
}

Answer 3

post {
    try {
        val customer = call.receive<Customer>()
        customerStorage.add(customer)
        call.respondText("Customer stored correctly", status = HttpStatusCode.Created)
    } catch (e: SerializationException) {
        call.respondText(e.localizedMessage, status = HttpStatusCode.UnprocessableEntity)
    } catch (e: Exception) {
        call.respondText(e.localizedMessage, status = HttpStatusCode.InternalServerError)
    }
}