Kotlinのdata classへJacksonでデシリアライズしようとして苦労した話 #ashiyakt

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Kotlinͷdata class΁ JacksonͰσγϦΞϥΠζ͠Α͏ ͱͯۤ͠࿑ͨ͠࿩ ୈճؔ੢,PUMJOษڧձ ! ೔ຊ,PUMJOϢʔβάϧʔϓ  ௕ᖒଠ࿠!OHTX@UBSP

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ࣗݾ঺հ w ௕ᖒଠ࿠!OHTX@UBSP w ,PUMJOΤϰΝϯδΣϦετ ࣗশ w ࡀɺֈ࠲ɺͱ͕େ޷͖

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Α͋͘ΔJSON

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{! "id": 123,! "title": "Kotlinೖ໳",! "deletedAt": null,! "author": {! "id": 456,! "name": "ͨΖ͏",! "paying": true! }! }

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{! "id": 123,! "title": "Kotlinೖ໳",! "deletedAt": null,! "author": {! "id": 456,! "name": "ͨΖ͏",! "paying": true! }! } Article

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{! "id": 123,! "title": "Kotlinೖ໳",! "deletedAt": null,! "author": {! "id": 456,! "name": "ͨΖ͏",! "paying": true! }! } User

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ొ৔Ϋϥε w"SUJDMF w6TFS

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JacksonͰσγϦΞϥΠζ͍ͨ͠ val objectMapper = ObjectMapper()! val article: Article =! objectMapper.readValue(json,! Article::class.java)! println(article)

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֦ுؔ਺ + reiﬁedܕύϥϝʔλ inline fun ! ObjectMapper.read(json: String): T =! readValue(json, javaClass())! ! val article: Article = objectMapper read json

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Articleͷఆٛ ͦͷ1 class Article {! var id: Long? = null! var title: String? = null! var author: User? = null! var deletedAt: Date? = null! ! override fun toString(): String =! "Article($id, $title, $author, $deletedAt)"! }

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Userͷఆٛ ͦͷ1 class User {! var id: Long? = null! var name: String? = null! var paying: Boolean = false! ! override fun toString(): String =! "User($id, $name, $paying)"! }

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Userͷఆٛ ͦͷ1 class User {! var id: Long? = null! var name: String? = null! var paying: Boolean = false! ! override fun toString(): String =! "User($id, $name, $paying)"! } σϑΥϧτ ίϯετϥΫλ WBSϓϩύςΟ TFUUFSHFUUFS

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Articleͷఆٛ ͦͷ2 data class Article(! var id: Long? = null,! var title: String? = null,! var author: User? = null,! var deletedAt: Date? = null! )

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Userͷఆٛ ͦͷ2 data class User(! var id: Long? = null,! var name: String? = null,! var paying: Boolean = false! )

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Userͷఆٛ ͦͷ2 data class User(! var id: Long? = null,! var name: String? = null,! var paying: Boolean = false! ) EBUBΫϥεʹͳͬͨͧ

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Userͷఆٛ ͦͷ2 data class User(! var id: Long? = null,! var name: String? = null,! var paying: Boolean = false! ) EBUBΫϥεʹͳͬͨͧ ͢΂ͯͷҾ਺ʹσϑΥϧτ஋ ͕͍ͭͯΔͷͰσϑΥϧτίϯετ ϥΫλ͕खʹೖΔͬΆ͍

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Userͷఆٛ ͦͷ2 data class User(! var id: Long? = null,! var name: String? = null,! var paying: Boolean = false! ) EBUBΫϥεʹͳͬͨͧ ͢΂ͯͷҾ਺ʹσϑΥϧτ஋ ͕͍ͭͯΔͷͰσϑΥϧτίϯετ ϥΫλ͕खʹೖΔͬΆ͍ WBSμαΠΑͶ

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Articleͷఆٛ ͦͷ3 data class Article(! @JsonProperty(“id") val id: Long,! @JsonProperty(“title") val title: String,! @JsonProperty(“author") val author: User,! @JsonProperty(“deletedAt") val deletedAt: Date? = null! )

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Userͷఆٛ ͦͷ3 data class User(! @JsonProperty(“id") val id: Long,! @JsonProperty(“name") val name: String,! @JsonProperty(“paying") val paying: Boolean = false! ) WBMʹͳͬͨ !+TPO1SPQFSUZ

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Userͷఆٛ ͦͷ3 data class User(! @JsonProperty(“id") val id: Long,! @JsonProperty(“name") val name: String,! @JsonProperty(“paying") val paying: Boolean = false! )

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Α͋͘Δʁ Πέͯͳ͍JSON

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{! "id": 123,! "title": "Kotlinೖ໳",! "deletedAt": null,! "userId": 456,! "userName": "ͨΖ͏",! "payingUser": true! }

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Articleͷఆٛ ͦͷ4 data class Article(! @JsonProperty(“id") val id: Long,! @JsonProperty(“title") val title: String,! @JsonProperty(“deletedAt") val deletedAt: Date? = null,! @JsonProperty(“userId") userId: Long,! @JsonProperty(“userName") userName: String,! @JsonProperty(“payingUser") payingUser: Boolean = false! ) {! val author: User = User(userId, userName, payingUser)! }

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Articleͷఆٛ ͦͷ5 data class Article(! val id: Long,! val title: String,! val author: User,! val deletedAt: Date? = null! ) {

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Articleͷఆٛ ͦͷ5 constructor(! @JsonProperty(“id") id: Long,! @JsonProperty(“title") title: String,! @JsonProperty(“deletedAt") deletedAt: Date? = null,! @JsonProperty(“userId") userId: Long,! @JsonProperty(“userName") userName: String,! @JsonProperty(“payingUser") payingUser: Boolean = false! ): this(! id = id,! title = title,! deletedAt = deletedAt,! author = User(userId, userName, payingUser)! )

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Java͔Β࢖͏

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kotlin: user.paying java : user.getPaying()

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kotlin: user.paying java : user.getPaying() μα͍

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Userͷఆٛ ͦͷ5 data class User(! @JsonProperty(“id") val id: Long,! @JsonProperty(“name") val name: String,! @JsonProperty(“paying") val paying: Boolean = false! ) {! fun isPaying(): Boolean = paying! }

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kotlin: user.copy(paying=false) ! java: user.copy(user.getId(), user.getName(), false)

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kotlin: user.copy(paying=false) ! java: user.copy(user.getId(), user.getName(), false) ΊΜͲ͍

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Userͷఆٛ ͦͷ6 data class User(! @JsonProperty(“id") val id: Long,! @JsonProperty(“name") val name: String,! @JsonProperty(“paying") val paying: Boolean = false! ) {! fun isPaying(): Boolean = paying! fun withPaying(paying: Boolean) = copy(paying = paying)! }

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Ҏ্

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͓·͚ Kotlinมଶจ๏

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fun f(x: String) {! x.fun String.() {! println(toUpperCase())! }()! } https://twitter.com/vreshetnikov/status/613487198801780736 ΑΓҾ༻

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x.(y())()! ! ϥΠϒίʔσΟϯά! Ͱ͖ͳ͔ͬͨΒΰϝϯω https://twitter.com/vreshetnikov/status/613464247784214529 ΑΓҾ༻

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object: (() -> Unit) ->! Unit by {} {} {} https://twitter.com/vreshetnikov/status/611677438620241921 ΑΓҾ༻

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fun(String.()->Unit).f() =! "A"() https://twitter.com/vreshetnikov/status/610624254996951040 ΑΓҾ༻

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͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠