I'm new to Kotlin & understanding the concepts as I move. Stuck in creating one type of Data class model where the response json structure as shown below
data class SPLPlayer(
#field:Json(name ="id") val playerId: String?,
val type: String?,
#field:Json(name ="value") val currentValue: String?,
#field:Json(name ="Confirm_XI") val isIn_XI: Boolean = false,
#field:Json(name ="Matches") val totalMatchs: String?,
#field:Json(name ="Position") val position: String?,
#field:Json(name ="Skill") val skill: String?,
#field:Json(name ="skill_name") val skillName: String?,
val teamId: String?,
val name: String?, // other keys to refer Name_Full, short_name
#field:Json(name ="Bowling") val bowler: SPLBowler? = null,
#field:Json(name ="Batting") val batsmen: SPLBatsmen? = null
)
data class SPLTeamInfo (
**How to parse the Team object which is dictionary**
)
Thanks & appreciate to every reader. Looking forward for the solution.
You should be able to use your own deserializer by adding annotation to a setter #set:JsonDeserialize() and passing your own deserializer implementation.
along the lines of:
import com.fasterxml.jackson.databind.annotation.JsonDeserialize
import com.fasterxml.jackson.databind.JsonDeserializer
.. rest of imports
// for a given simplified json string
val json: String = """{"teams":{"1":{"name":"foo"},"2":{"name":"bar"}}}"""
class MyDeserializer : JsonDeserializer<List<Team>> {
override fun deserialize(json: JsonElement?, typeOfT: Type?, context: JsonDeserializationContext?): List<Team>? {
// iterate over each json element and return list of parsed teams
}
}
data class JsonResp (
#set:JsonDeserialize(using = MyDeserializer::class)
var teams: List<Team>
)
data class Team (
var id: String, // this is going to be a team key
var name: String
)
Tried GitHub search with query #set:JsonDeserialize and it shows thousands of examples.
Related
I am trying to implement a custom deserializer and when I try to install it on the ObjectMapper it never gets invoked, but when I use it directly as an annotation on the class, it does. Can someone explain why and how I can actually install it on the object mapper itself?
This is never invoked
val bug = ObjectMapper().registerModule(KotlinModule.Builder().build())
.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
.registerModule(SimpleModule().addDeserializer(Bug::class.java, BugDeserializer()))
.readValue(bugStream, Bug::class.java)
data class Bug(
#JsonProperty("rptno")
val id: Long,
#JsonProperty("status")
#JsonDeserialize(using = StatusDeserializer::class)
val status: Status,
#JsonProperty("reported_date")
val reportedDate:Instant,
#JsonProperty("updated_date")
val updatedDate: Instant,
// val pillar: String = "",
#JsonProperty("product_id")
#JsonDeserialize(using = ProductDeserializer::class)
val product: Product,
#JsonProperty("assignee")
val assignee: String,
// val serviceRequests: List<Long> = listOf(),
#JsonProperty("subject")
val title: String,
#JsonProperty("bug_type")
val type: String
)
But, this does:
val bug = ObjectMapper().registerModule(KotlinModule.Builder().build())
.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
.readValue(bugStream, Bug::class.java)
#JsonDeserialize(using = BugDeserializer::class)
data class Bug(
#JsonProperty("rptno")
val id: Long,
#JsonProperty("status")
#JsonDeserialize(using = StatusDeserializer::class)
val status: Status,
#JsonProperty("reported_date")
val reportedDate:Instant,
#JsonProperty("updated_date")
val updatedDate: Instant,
// val pillar: String = "",
#JsonProperty("product_id")
#JsonDeserialize(using = ProductDeserializer::class)
val product: Product,
#JsonProperty("assignee")
val assignee: String,
// val serviceRequests: List<Long> = listOf(),
#JsonProperty("subject")
val title: String,
#JsonProperty("bug_type")
val type: String
)
```kotlin
I have the following classes
class A(
val value1: String,
val value2: String,
val value3: String,
val value4: String,
val value5: String,
)
class B(
val value1: String,
val value2: String,
val value3: String,
val value4: String,
val value5: String,
) {
compaion object {
from(a: A) = B(
value1 = a.value1,
value2 = a.value2,
value3 = a.value3,
value4 = a.value4,
value5 = a.value5,
)
}
}
I write codes as follows when I want to create an instance of B from A
val a: A = getAFromSomewhere()
val b: B = B.from(a)
I have a lot of codes as above and It's very boring for me to write the factory method, 'from'. Is there any easy way of writing this kind of codes in Kotlin??
You might be interested in the MapStruct library.
https://mapstruct.org/
It helps map between two objects(DTO, Entity, etc..).
Code
In this example we want to map between a Person (Model) and a PersonDto (DTO).
data class Person(var firstName: String?, var lastName: String?, var phoneNumber: String?, var birthdate: LocalDate?)
data class PersonDto(var firstName: String?, var lastName: String?, var phone: String?, var birthdate: LocalDate?)
The MapStruct converter:
#Mapper
interface PersonConverter {
#Mapping(source = "phoneNumber", target = "phone")
fun convertToDto(person: Person) : PersonDto
#InheritInverseConfiguration
fun convertToModel(personDto: PersonDto) : Person
}
Usage:
val converter = Mappers.getMapper(PersonConverter::class.java) // or PersonConverterImpl()
val person = Person("Samuel", "Jackson", "0123 334466", LocalDate.of(1948, 12, 21))
val personDto = converter.convertToDto(person)
println(personDto)
val personModel = converter.convertToModel(personDto)
println(personModel)
From: https://github.com/mapstruct/mapstruct-examples/tree/master/mapstruct-kotlin
I have the following data classes:
sealed class ExampleDto
object Type1ExampleDto : ExampleDto()
object Type2ExampleDto : ExampleDto()
data class Type3ExampleDto(val name: Int, val age: Int) : ExampleDto()
data class Type4ExampleDto(val name: Int, val age: Int) : ExampleDto()
data class Type5ExampleDto(val email: String) : ExampleDto()
data class Type6ExampleDto(val name: Int, val age: Int, val email: String) : ExampleDto()
In particular, Type3ExampleDto, Type4ExampleDto and Type6ExampleDto share some common fields but it's important for my business logic to distinguish between types (i.e. even if Type3ExampleDto and Type4ExampleDto are identical, I have to know if I'm in the type3 or type4 case).
In one of my method I have the following call:
when (type) {
is Type3ExampleDto -> myMethod(type.vote, type.text)
is Type4ExampleDto -> myMethod(type.vote, type.text)
is Type6ExampleDto -> myMethod(type.vote, type.text)
else -> null
}
I find very ugly that I'm doing the same operation in all 3 cases and repeating the same line...
It makes sense to made Type3ExampleDto, Type4ExampleDto and Type6ExampleDto an implementation of some kind of interface just because only in this point I'm doing this kind of ugly repetition?
If all three dtos implement the following interface
interface MyInterface{
fun getVote() : Int
fun getText() : String
}
I can write:
if (type is MyInterface) {
myMethod(type.getVote(), type.getText())
}
So, it's acceptable to create this interface just to solve this isolated repetition?
Thanks
Note you can do it much more cleanly like this:
interface NameAndAgeDto {
val name: Int
val age: Int
}
data class Type3ExampleDto(override val name: Int, override val age: Int) : ExampleDto(), NameAndAgeDto
if (type is NameAndAgeDto) {
myMethod(type.name, type.age)
}
Whether it's "acceptable" is opinion. Looks fine to me.
You may change your model to have your logic based on behaviour instead of inheritance.
This way of modelling is based on principles of (but ain't exactly) Strategy Design Pattern.
interface HasName {
val name: String
}
interface HasAge {
val age: Int
}
interface HasEmail {
val email: String
}
object Type1
object Type2
data class Type3(
override val name: String,
override val age: Int
) : HasName, HasAge
data class Type4(
override val name: String,
override val age: Int
) : HasName, HasAge
data class Type5(
override val email: String
) : HasEmail
data class Type6(
override val name: String,
override val age: Int,
override val email: String
) : HasName, HasAge, HasEmail
// Then you can pass any object to it.
fun main(obj: Any) {
// Koltin type-casts it nicely to both interfaces.
if (obj is HasName && obj is HasAge) {
myMethod(text = obj.name, vote = obj.age)
}
}
fun myMethod(vote: Int, text: String) {
}
If you still want all the types to belong to some parent type, you can use marker interface (without any methods).
interface DTO
interface HasName {
val name: String
}
interface HasAge {
val age: Int
}
interface HasEmail {
val email: String
}
object Type1 : DTO
object Type2 : DTO
data class Type3(
override val name: String,
override val age: Int
) : HasName, HasAge, DTO
data class Type4(
override val name: String,
override val age: Int
) : HasName, HasAge, DTO
data class Type5(
override val email: String
) : HasEmail, DTO
data class Type6(
override val name: String,
override val age: Int,
override val email: String
) : HasName, HasAge, HasEmail, DTO
// Here, it is DTO instead of Any
fun main(obj: DTO) {
if (obj is HasName && obj is HasAge) {
myMethod(text = obj.name, vote = obj.age)
}
}
And use sealed class instead of marker interface if you need classes as enum.
In that case, when over sealed class is exhaustive with all options without null ->.
My problem is that I need to transform a data class in kotlin to a map, because I need to work with this structure as a requirement, because this response will be used for a groovy classes and there is a post-process where there are validations iterations etc, with this map. My data class is the next (Podcast):
data class PodCast(val id: String, val type: String, val items: List<Item>, val header: Header, val cellType:String? = "")
data class Item(val type: String, val parentId: String, val parentType: String, val id: String, val action: Action, val isNew: Boolean)
data class Header(val color: String, val label: String)
data class Action(val type: String, val url: String)
I made the transformation manually, but I need a more sophisticated way to achieve this task.
Thanks.
You can also do this with Gson, by serializing the data class to json, and then deserializing the json to a map. Conversion in both directions shown here:
val gson = Gson()
//convert a data class to a map
fun <T> T.serializeToMap(): Map<String, Any> {
return convert()
}
//convert a map to a data class
inline fun <reified T> Map<String, Any>.toDataClass(): T {
return convert()
}
//convert an object of type I to type O
inline fun <I, reified O> I.convert(): O {
val json = gson.toJson(this)
return gson.fromJson(json, object : TypeToken<O>() {}.type)
}
See similar question here
I have done this very simple. I got the properties of the object, just using the .properties groovy method, which gave me the object as a map.
Hi there im trying to make a generic client and trying to parse the json to a object.
gson?.fromJson(khttpResponse.jsonObject.toString(),
UserInfo::class.java)
works.
val listType = object : TypeToken<T>() {}.type
gson?.fromJson(khttpResponse.jsonObject.toString(), listType)
Doesnt't work. So my question is there a workaround to to parse json in gson or do you guys use some other libary?
UserInfo:
open class UserInfo (
val profileId: String,
val code: String,
val message: String,
val path: String,
val profile: Profile,
val errorDetail: Any
)
data class Profile(
val firstname: String,
val lastname: String
)