Mapster Kotlin

(Experimental)

• Fun and easily mapper from object to another
• Runtime mapping
• Nested mapping
• Array & List mapping
• inverse mapping

stable-version : 0.4.0

Gradle Installation

  repositories {
    // using github packages
    maven {
        url = "https://maven.pkg.github.com/liodali/KotlinMapster"
        credentials {
            username = "YOUR-USERNAME"
            password = "YOUR-TOKEN-GITHUB"
        }
    }
}
dependencies {
    implementations "com.dali.hamza:mapster-ktx:version"
}

simple example :

  data class Person(val email: String, val password: String, val firstName: String)
  data class PersonDTO(val email: String, val firstName: String)
  
  val person = Person("[email protected]", "person", "person",)
  
  val dto = person.adaptTo(PersonDTO::class)

mapping list example :

data class Person(val email: String, val password: String, val firstName: String)
data class PersonDTO(val email: String, val firstName: String)

val persons = listOf(Person("[email protected]", "person", "person",), Person("[email protected]", "person", "person",))

val dtos = persons.adaptListTo(PersonDTO::class)

Basic Annotation :

• use MapTo annotation to map from an attribute to another with difference name

data class Person(@MapTo("login") val email: String, val password: String, val firstName: String, val adr: Address)

data class LoginUser(val login: String, val password: String)

val login = person.adaptTo(LoginUser::class)

Properties MapTo

Attribute	description
destAttName	(String) name of attribute destination

---

• use CombineTo annotation to combine attributes to another with difference name

  data class User(
    @CombineTo(destAtt = "fullName", index = 0) val firstName: String,
    @CombineTo(destAtt = "fullName", index = 1) val lastName: String,
    val CIN: String
)

data class UserDTO(
    val fullName: String,
    val CIN: String
)

val dto = user.adaptTo(UserDTO::class)

Properties CombineTo

---

Attribute	description
destAtt	(String) name of attribute destination
separator	(String) separator between the combined values
index	(Int) position in final result

Advanced Examples

• BaseMapper : mapper instance
  • you can use IMapper interface to pass it into a DI
  • support list mapping
  • support nested list mapping and nested Transformation

data class User(val name: String, val password: String, val country: String, val phone: String)
data class UserDTO(val name: String, val password: String)

val faker = Faker() // faker object to generate random data
val user = User(
    name = faker.name.firstName(),
    password = "1234",
    country = faker.address.country(),
    phone = faker.phoneNumber.phoneNumber()
)

val mapper = BaseMapper.from(user).to(UserDTO::class)
val dto = mapper.adapt()

Map List of object

data class User(val name: String, val password: String)
data class UserDTO(val name: String?, val password: String?)

val users = emptyList<User>().toMutableList()
for (i in 0..2) {
    val name = faker.name.firstName()
    val pwd = "1234"
    users.add(User(name, password = pwd))
}
// new way to create instance of BaseMapper
val mapper = BaseMapper<User, UserDTO>()
    .to(UserDTO::class).ignore("password")

val dtoList = mapper.adaptList(users)

Inverse Mapping List

 data class User(val name: String, val password: String)
 data class UserDTO(val name: String, val password: String)

 val mapper = BaseMapper<User, UserDTO>()
    .from(User::class)
    .to(UserDTO::class)
  (1..3).forEach { _ ->
  
    val name = faker.name.firstName()
    val pwd = "1234"
    listDTOs.add(UserDTO(name, password = pwd))
  }
 /// adaptListInverse for backward mapping from dto to initial object
 val listUser = mapper.adaptListInverse(listDTOs)

Mapper Manipulation

• you can create custom configuration for BaseMapper to manipulate data during mapping

 data class User(val name: String, val password: String, val dateCreation: String, val age: Int)
 data class UserDTO(val name: String?, val password: String?, val dateCreation: String?, val age: Int?)

 val name = faker.name.firstName()
 val user = User(name, password = "1234", "12/12/2020", 20)

 /// ConfigMapper Instance
 val configMapper = ConfigMapper<User, UserDTO>()
    .ignoreAtt("age") // ignore field
    .ignoreIf("dateCreation") {     // conditional ignore
        it.dateCreation.isEmpty()  //
    }
    .transformation("password") { user -> //transformation
        hashPassword(user.password)
    }.map("name", "login") // map field to another destination field
 /// BaseMapper Instance
 val mapper = BaseMapper.from(user).to(UserDTO::class).newConfig(configMapper)
 /// map user to dto
 val dto = mapper.adapt()

MultiMapping from multiple fields to single field

• should be used with transformation or InverseTransformation except that is unnecessary to use it

 data class User(val firstName: String, val lastName: String, val password: String)
 data class UserDTO(val fullName: String, val password: String)
 val mapper = BaseMapper.from(user)
  .to(UserDTO::class)
  .transformation(
    "fullName"
  ) { user ->
    user.firstName + " " + user.lastName
  }
  .mapMultiple(arrayOf("firstName", "lastName"), "fullName")

val dto = mapper.adapt()

Inverse Mapping

data class User(val firstName: String, val lastName: String, val password: String)
data class UserDTO(val fullName: String, val password: String)

val name = faker.name.firstName()
val lastName = faker.name.lastName()
val pwd = "1234"
val user = User(name, lastName, password = pwd)

val mapper = BaseMapper.from(user)
    .to(UserDTO::class).transformation(
        "fullName"
    ) { user ->
        user.firstName + " " + user.lastName
    }.inverseTransformation(
        "firstName"
    ) { dto ->
        dto.fullName.split(" ").first()
    }.inverseTransformation(
        "lastName"
    ) { dto ->
        dto.fullName.split(" ").last()
    }.mapMultiple(arrayOf("firstName", "lastName"), "fullName")

val dto = mapper.adapt()
// reverse mapping from dto to real object
val realObject = mapper.adaptInverse(dto)

• you can apply the same manipulation use BaseMapper without need to create new ConfigurationMapper

Ignore

To ignore Field, you need to mark it nullable

• Ignore Field :

 data class User(val name: String, val password: String)
 data class UserDTO(val name: String?, val password: String?)

 val name = faker.name.firstName()
 val user = User(name, password = "1234")
 val mapper = BaseMapper.from(user).to(UserDTO::class)
    .ignore("password")
 val dto = mapper.adapt()

• Conditional Ignore Field :

  You can ignore Field Conditionally with condition base on source, when condition is met,the field that has the same name in destination object will be skipped.

  You can combine it with map to skip field that has different name in destination object.

data class User(val name: String, val password: String)
data class UserDTO(val name: String?, val password: String?)

val name = faker.name.firstName()

val user = User(name, password = "1234")
val mapper = BaseMapper.from(user).to(UserDTO::class)
    .ignore("password")
val dto = mapper.adapt()

Transformation :

you can compute new values using transformation,example hash the password entered by the user

data class User(val name: String, val email: String, val password: String, val country: String)
data class LoginDTO(val login: String?, val password: String?)
// data preparation
val name = faker.name.firstName()
val email = faker.internet.email()
val country = faker.address.country()
val user = User(name, email, "1234", country)

//BaseMapper builder with mapTo and transformation 
val mapper = BaseMapper.from(user).to(LoginDTO::class)
    .mapTo("email", "login")
    .transformation("password") { user ->
        hashPassword(user.password)
    }
val dto = mapper.adapt()

Inverse Transformation :

you can reverse value computed using transformation,example reverse concat of firstName and lastName entered by the user

data class User(val firstName: String, val lastName: String, val password: String)
data class UserDTO(val fullName: String, val password: String)

val name = faker.name.firstName()
val lastName = faker.name.lastName()
val pwd = "1234"
val user = User(name, lastName, password = pwd)

//BaseMapper builder with mapTo and transformation 
val mapper = BaseMapper.from(user).to(LoginDTO::class)
    .mapTo("email", "login")
    .transformation(
        "fullName"
    ) { user ->
        user.firstName + " " + user.lastName
    }.inverseTransformation(
        "firstName"
    ) { dto ->
        dto.fullName.split(" ").first()
    }.inverseTransformation(
        "lastName"
    ) { dto ->
        dto.fullName.split(" ").last()
    }

MapTo

you can map field with difference names using MapTo

data class User(val name: String, val email: String, val password: String, val country: String)
data class LoginDTO(val login: String?, val password: String?)

val user = User(faker.name.firstName(), faker.internet.email(), password = "1234", faker.address.country())

val mapper = BaseMapper.from(user).to(UserDTO::class)
    .mapTo("email", "login")
val dto = mapper.adapt()

MapMultiple

you can map multiple fields to single destination field using mapMultiple the best usage is with InverseTransformation (see example above)

data class User(val firstName: String, val lastName: String, val password: String)
data class UserDTO(val fullName: String, val password: String)

val name = faker.name.firstName()
val lastName = faker.name.lastName()
val pwd = "1234"
val user = User(name, lastName, password = pwd)

val mapper = BaseMapper.from(user).to(UserDTO::class)
    .mapMultiple(arrayOf("firstName", "lastName"), "fullName")
val dto = mapper.adapt()

PS

• To create Github personal token follow this link and also you need to choose read:packages :
  • https://docs.github.com/en/free-pro-team@latest/github/authenticating-to-github/creating-a-personal-access-token