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

第2回関西Kotlin勉強会( http://connpass.com/event/18102/ )の発表資料です。

1. Kotlinͷdata class΁ JacksonͰσγϦΞϥΠζ͠Α͏ ͱͯۤ͠࿑ͨ͠࿩ 
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2. ࣗݾ঺հ w ௕ᖒ
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3. Α͋͘ΔJSON
4. {! "id": 123,! "title": "Kotlinೖ໳",! "deletedAt": null,! "author": {! "id": 456,! "name": "ͨΖ͏",! "paying": true! }! }
5. {! "id": 123,! "title": "Kotlinೖ໳",! "deletedAt": null,! "author": {! "id": 456,! "name": "ͨΖ͏",! "paying": true! }! } Article
6. {! "id": 123,! "title": "Kotlinೖ໳",! "deletedAt": null,! "author": {! "id": 456,! "name": "ͨΖ͏",! "paying": true! }! } User
7. ొ৔Ϋϥε w"SUJDMF
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8. JacksonͰσγϦΞϥΠζ͍ͨ͠ val objectMapper = ObjectMapper()! val article: Article =! objectMapper.readValue(json,! Article::class.java)! println(article)
9. ֦ுؔ਺ + reifiedܕύϥϝʔλ inline fun <reified T> ! ObjectMapper.read(json: String): T =! readValue(json, javaClass<T>())! ! val article: Article = objectMapper read json
10. 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, $deletedAt)"! }
11. Userͷఆٛ ͦͷ1 class User {! var id: Long? = null! var name: String? = null! var paying: Boolean = false! ! override fun toString(): String =! "User($id, $name, $paying)"! }
12. Userͷఆٛ ͦͷ1 class User {! var id: Long? = null! var name: String? = null! var paying: Boolean = false! ! override fun toString(): String =! "User($id, $name, $paying)"! } σϑΥϧτ
    ίϯετϥΫλ WBSϓϩύςΟ
    
    TFUUFSHFUUFS
13. 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 EBUBΫϥεʹ͍ͨ͠ͳʂ
14. Articleͷఆٛ ͦͷ2 data class Article(! var id: Long? = null,! var title: String? = null,! var author: User? = null,! var deletedAt: Date? = null! )
15. Userͷఆٛ ͦͷ2 data class User(! var id: Long? = null,! var name: String? = null,! var paying: Boolean = false! )
16. Userͷఆٛ ͦͷ2 data class User(! var id: Long? = null,! var name: String? = null,! var paying: Boolean = false! ) EBUBΫϥεʹͳͬͨͧ
17. Userͷఆٛ ͦͷ2 data class User(! var id: Long? = null,! var name: String? = null,! var paying: Boolean = false! ) EBUBΫϥεʹͳͬͨͧ ͢΂ͯͷҾ਺ʹσϑΥϧτ஋ ͕͍ͭͯΔͷͰσϑΥϧτίϯετ ϥΫλ͕खʹೖΔͬΆ͍
18. Userͷఆٛ ͦͷ2 data class User(! var id: Long? = null,! var name: String? = null,! var paying: Boolean = false! ) EBUBΫϥεʹͳͬͨͧ ͢΂ͯͷҾ਺ʹσϑΥϧτ஋ ͕͍ͭͯΔͷͰσϑΥϧτίϯετ ϥΫλ͕खʹೖΔͬΆ͍ WBSμαΠΑͶ
19. 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! )
20. Userͷఆٛ ͦͷ3 data class User(! @JsonProperty(“id") val id: Long,! @JsonProperty(“name") val name: String,! @JsonProperty(“paying") val paying: Boolean = false! ) WBMʹͳͬͨ !+TPO1SPQFSUZ
21. Userͷఆٛ ͦͷ3 data class User(! @JsonProperty(“id") val id: Long,! @JsonProperty(“name") val name: String,! @JsonProperty(“paying") val paying: Boolean = false! )
22. Α͋͘Δʁ Πέͯͳ͍JSON
23. {! "id": 123,! "title": "Kotlinೖ໳",! "deletedAt": null,! "userId": 456,! "userName": "ͨΖ͏",! "payingUser": true! }
24. 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)! }
25. 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)! } BVUIPS͕
    EBUBͷԸܙΛड͚ͳ͍ ίϯετϥΫλ͕
    ඒ͘͠ͳ͍
26. Articleͷఆٛ ͦͷ5 data class Article(! val id: Long,! val title: String,! val author: User,! val deletedAt: Date? = null! ) {
27. 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)! )
28. Java͔Β࢖͏
29. kotlin: user.paying java : user.getPaying()
30. kotlin: user.paying java : user.getPaying() μα͍
31. 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! }
32. kotlin: user.copy(paying=false) ! java: user.copy(user.getId(), user.getName(), false)
33. kotlin: user.copy(paying=false) ! java: user.copy(user.getId(), user.getName(), false) ΊΜͲ͍
34. 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)! }
35. Ҏ্
36. ͓·͚ Kotlinมଶจ๏
37. fun f(x: String) {! x.fun String.() {! println(toUpperCase())! }()! } https://twitter.com/vreshetnikov/status/613487198801780736 ΑΓҾ༻
38. x.(y())()! ! ϥΠϒίʔσΟϯά! Ͱ͖ͳ͔ͬͨΒΰϝϯω https://twitter.com/vreshetnikov/status/613464247784214529 ΑΓҾ༻
39. object: (() -> Unit) ->! Unit by {} {} {} https://twitter.com/vreshetnikov/status/611677438620241921 ΑΓҾ༻
40. fun(String.()->Unit).f() =! "A"() https://twitter.com/vreshetnikov/status/610624254996951040 ΑΓҾ༻
41. ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠