Code generation for converters between data class by KAPT.

See the blog (中文博客) for more detail.

Usage

dependency

// for build.gradle.kts
repositories {
    maven("https://jitpack.io")
}

dependencies {
    kapt("com.github.lexcao:konverter:master-SNAPSHOT")
    implementation("com.github.lexcao:konverter-annotation:master-SNAPSHOT")
}

// for build.gradle
repositories {
    maven { url 'https://jitpack.io' }
}

dependencies {
    kapt 'com.github.lexcao:konverter:master-SNAPSHOT'
    implementation 'com.github.lexcao:konverter-annotation:master-SNAPSHOT'
}

Example code here

@Konvertable(
    To(name = "LoginDTO", pick = ["username", "password"]),
    To(name = "UserListDTO", omit = ["password"])
)
@Konvert(to = UserVO::class)
data class UserEntity(
    val id: Long,
    @Konvert.Field("name")
    val username: String,
    val password: String,
    @Konvert.By(GenderEnumConverter::class)
    val gender: Int
)

Then generate by compileKotlin

For @Konvertable

/**
 *  Auto generated code by @Konvertable
 */
data class LoginDTO(
  val username: String,
  val password: String
)

/**
 *  Auto generated code by @Konvertable
 */
data class UserListDTO(
  val id: Long,
  val username: String,
  val gender: Int
)

/**
 *  Auto generated code by @Konvert
 */
fun UserEntity.toLoginDTO(username: String = this@toLoginDTO.username, password: String =
    this@toLoginDTO.password): LoginDTO = LoginDTO(username=username,password=password)

/**
 *  Auto generated code by @Konvert
 */
fun LoginDTO.toUserEntity(
  id: Long = 0L,
  username: String = this@toUserEntity.username,
  password: String = this@toUserEntity.password,
  gender: Int = 0
): UserEntity = UserEntity(id=id,username=username,password=password,gender=gender)

/**
 *  Auto generated code by @Konvert
 */
fun UserEntity.toUserListDTO(
  id: Long = this@toUserListDTO.id,
  username: String = this@toUserListDTO.username,
  gender: Int = this@toUserListDTO.gender
): UserListDTO = UserListDTO(id=id,username=username,gender=gender)

/**
 *  Auto generated code by @Konvert
 */
fun UserListDTO.toUserEntity(
  id: Long = this@toUserEntity.id,
  username: String = this@toUserEntity.username,
  password: String = "",
  gender: Int = this@toUserEntity.gender
): UserEntity = UserEntity(id=id,username=username,password=password,gender=gender)

/**
 *  Auto generated code by @Konvert
 */
fun UserEntity.toRegisterDTO(
  username: String = this@toRegisterDTO.username,
  password: String = this@toRegisterDTO.password,
  gender: Int = this@toRegisterDTO.gender
): RegisterDTO = RegisterDTO(username=username,password=password,gender=gender)

/**
 *  Auto generated code by @Konvert
 */
fun RegisterDTO.toUserEntity(
  id: Long = 0L,
  username: String = this@toUserEntity.username,
  password: String = this@toUserEntity.password,
  gender: Int = this@toUserEntity.gender
): UserEntity = UserEntity(id=id,username=username,password=password,gender=gender)

For @Konvert

// the class to convert to 
data class UserVO(
    val id: String,
    val name: String,
    val gender: GenderEnum
)

enum class GenderEnum {
    MALE, FEMALE;
}

object GenderEnumConverter : Konvert.KonvertBy<Int, GenderEnum> {
    override fun Int.forward(): GenderEnum {
        return GenderEnum.values()[this]
    }

    override fun GenderEnum.backward(): Int {
        return this.ordinal
    }
}

// then generate
/**
 *  Auto generated code by @Konvert
 */
fun UserEntity.toUserVO(
  id: String = this@toUserVO.id.toString(),
  name: String = this@toUserVO.username,
  gender: GenderEnum = with(GenderEnumConverter) { this@toUserVO.gender.forward() }
): UserVO = UserVO(id=id,name=name,gender=gender)

/**
 *  Auto generated code by @Konvert
 */
fun UserVO.toUserEntity(
  id: Long = this@toUserEntity.id.toLong(),
  username: String = this@toUserEntity.name,
  password: String = "",
  gender: Int = with(GenderEnumConverter) { this@toUserEntity.gender.backward() }
): UserEntity = UserEntity(id=id,username=username,password=password,gender=gender)

Notes

the rules of conversion

• If converting to String type, it will use toString() while the type is not match
• If converting to primitive type, it will use default value of primitive type when missing
• If converting to nullable type, it will use null for default value when missing
• It will need be assigned explicitly when converting to reference type (excepting String) or unknown type

Next

• code optimization and test case
• support the default value of object and collection
• support nested class
• support for Java
• fix bugs
• support for using the default value of parameters on constructors or fields on class from original when missing(from now, Kotlin KAPT is only support for default value of fields, but not for parameters)