Kotlin 数据类和 LocalDateTime

Question

我有票类:

data class Ticket(
        var contact_email : String? = null,
        var date_opened : LocalDateTime? = null
)

但我在从字符串读取时出错:

Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of java.time.LocalDateTime (no Creators, like default construct, exist): no String-argument constructor/factory method to deserialize from String value ('2017-11-13T06:40:00Z') at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: rnd_classifier.model.Ticket["date_opened"])

我尝试添加注释但没有成功:

data class Ticket(
        var contact_email : String? = null,

        @JsonSerialize(using = ToStringSerializer::class)
        @JsonDeserialize(using = LocalDateTimeDeserializer::class)
        var date_opened : LocalDateTime? = null
)

如何修复它？

Answer 1

您的问题更多是关于 jackson 而不是 kotlin。
如 serialize/deserialize java 8 java.time with Jackson JSON mapper 中所述

你需要添加一个额外的gradle依赖来解决它

implementation("com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.9.5")

之后它应该工作

import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule
import org.testng.annotations.Test
import java.time.LocalDateTime

class SoTest {

    data class Ticket(
            var contact_email: String? = null,
            var date_opened: LocalDateTime? = null
    )

    @Test
    fun checkSerialize() {
        val mapper = ObjectMapper()
        mapper.registerModule(JavaTimeModule())
        val ticket = mapper.readValue(inputJsonString, Ticket::class.java)
        assert ("$ticket"=="Ticket(contact_email=contact@ema.il, date_opened=2017-11-13T06:40)")
    }

    val inputJsonString = """{
        "contact_email": "contact@ema.il",
        "date_opened": "2017-11-13T06:40:00Z"
    }""".trimIndent()

}