Convert string data representation back to Kotlin Data Class - kotlin

Question

In Kotlin how is possible to convert a data class from its string representation back to the actual data class without having to manually parse the string?
for example, I have the next data class where both Interest and EmploymentType are enums, being the second element a List.
data class DataFilter(val mainInterest: Interest, val employments: List<EmploymentType>)
with toString I can get the contents its string representation, but if I want to get it back to a data class, how is it done?

Answer 1

For this purpose, you need to use a serialization library. I recommend you use Kotlinx.serialization library. This will help you convert the data object into a JSON String and convert it back to the data object easily.
You can follow the guideline to setup Kotlinx.serialization library.
After the setup is done, look at the following example:
I will define both enum classes Interest and EmploymentType, and the DataFilter class:
import kotlinx.serialization.Serializable
import kotlinx.serialization.decodeFromString
import kotlinx.serialization.encodeToString
import kotlinx.serialization.json.Json
enum class Interest {
SPORTS,
BOOKS,
TRAVEL,
FOOD,
TECHNOLOGY,
ART,
OTHER
}
enum class EmploymentType {
FULL_TIME,
PART_TIME,
CONTRACT,
FREELANCE,
OTHER
}
#Serializable //You have to annotate your class as Serializable to make it works.
data class DataFilter(
val mainInterest: Interest,
val employment: List<EmploymentType>
)
Notice that Interest and EmploymentType are not annotated as #Serializable because enums are Serializable by default, but if you defined any other normal classes to use with DataFilter, then you have to annotate them as well.
Next, I will show you how conversions work:
fun main() {
val filter = DataFilter(
mainInterest = Interest.BOOKS,
employment = listOf(EmploymentType.FULL_TIME, EmploymentType.FREELANCE)
)
// Converting filter object into JSON String:
val filterAsJsonString = Json.encodeToString(filter)
println(filterAsJsonString) //prints {"mainInterest":"BOOKS","employment":["FULL_TIME","FREELANCE"]}
//Convert JSON String back to data object:
val filterAsDataObject: DataFilter = Json.decodeFromString(filterAsJsonString)
println(filterAsDataObject) //prints DataFilter(mainInterest=BOOKS, employment=[FULL_TIME, FREELANCE])
}