Property Mapping¶

When mapping between two classes, it's common for properties to have different names. AutoMapper provides the @PropertyMapping annotation to handle these scenarios gracefully.

Use the propertyMappings array within @AutoMapper to define a list of remapping. Both from (the name in the source class) and to (the name in the target class) parameters are mandatory.

Renaming Data Class Properties¶

Models:

// Domain
data class User(val id: Long, val fullName: String)

// Data Layer
data class UserEntity(val userId: Long, val name: String)

Mapping Definition:

import io.github.jacksever.automapper.annotation.AutoMapper
import io.github.jacksever.automapper.annotation.PropertyMapping

@AutoMapper(
    propertyMappings = [
        PropertyMapping(from = "id", to = "userId"),
        PropertyMapping(from = "fullName", to = "name")
    ]
)
fun userMapper(user: User): UserEntity

Generated Code:

fun User.asUserEntity(): UserEntity = UserEntity(
    userId = id,
    name = fullName
)

Tip

If the mapping is reversible, the processor will automatically generate the reverse mapping for the properties as well (e.g., userId to id).

Mapping Dissimilar Sealed Classes¶

@PropertyMapping is also powerful enough to map between sealed class or enum hierarchies that don't share the same names for their members.

Models:

// Domain
enum class Status { OPEN, IN_PROGRESS, CLOSED }

// UI Layer
enum class UiStatus { Active, Pending, Done }

Mapping Definition:

@AutoMapper(
    propertyMappings = [
        PropertyMapping(from = "OPEN", to = "Active"),
        PropertyMapping(from = "IN_PROGRESS", to = "Pending"),
        PropertyMapping(from = "CLOSED", to = "Done")
    ]
)
fun statusMapper(status: Status): UiStatus