retrofit mvvm

https://www.youtube.com/watch?v=sBCE_hOFnQU&t=68s

add dependencys
  // Retrofit
  implementation 'com.squareup.retrofit2:retrofit:2.9.0'
  implementation 'com.squareup.retrofit2:converter-gson:2.6.0'
  implementation 'com.squareup.okhttp3:logging-interceptor:4.2.1'

  // Coroutine
  implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.9'
  implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.9'
  implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0'
  
Data
  data class DataCart (
      val cartId: Int,
      val cartTitle: String,
      val cartDescription: String,
      val cartPrice: Int,
      val cartQty: Int
  )

Interface API
interface LoginAPI {
    @GET("employee/login")
    suspend fun loginValidation(
        @Query("email") email: String,
        @Query("password") password: String
    ): Response<Employee>
    
    
    // <-- POST --> DONT INSERT THIS
    @FormUrlEncoded
    @POST("user/edit_address/")
    suspend fun editUserAddress(
        @Field("user_id") user_id: Int,
        @Field("permission") permission: String,
        @Field("address") address: String,
        @Field("address_detail") addressDetail: String,
        @Field("user_latitude") user_latitude: Double,
        @Field("user_longitude") user_longitude: Double
    ): Response<User>
    
    // <-- PATH --> DONT INSERT THIS
    @GET("user/{user_id}")
    suspend fun getUserById(
        @Path("user_id") userId: Int
    ): Response<User>

}

Instance
object Instance {
    val retrofit by lazy {
        Retrofit.Builder()
            .baseUrl("https://staging.   .com/api/")
            .addConverterFactory(GsonConverterFactory.create())
            .build()
    }

    val loginAPI by lazy{
        retrofit.create(LoginAPI::class.java)
    }
}

Repository
class LoginRepository {
    suspend fun loginValidation(email: String, password: String): Response<Employee>{
        return Instance.loginAPI.loginValidation(email, password)
    }
}

ViewModel
class LoginViewModel(private val repository: LoginRepository): ViewModel() {
        val responseLogin: MutableLiveData<Response<Employee>> = MutableLiveData()

        fun loginValidation(email: String, password: String){
        viewModelScope.launch {
            val response = repository.loginValidation(email, password)
            responseLogin.value = response
        }
    }   
}

ViewModelFactory
class LoginViewModelFactory(
    private val repository: LoginRepository
) : ViewModelProvider.Factory {
    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
        return LoginViewModel(repository) as T
    }
}


Activity
val repository = LoginRepository()
val viewModelFactory = LoginViewModelFactory(repository)

viewModel = ViewModelProvider(this, viewModelFactory).get(LoginViewModel::class.java)
viewModel.loginValidation(text_email, text_password)
viewModel.responseLogin.observe(this, Observer { response ->
    if (response.isSuccessful()) {
        sharedPreferences.run {
            put(Constant.PREF_IS_LOGIN, true)
            put(Constant.PREF_EMPLOYEE_ID, response.body()!!.employee_id.toString())
            put(Constant.PREF_FULLNAME, response.body()!!.fullname)
            put(Constant.PREF_USERNAME, response.body()!!.username)
            put(Constant.PREF_GENDER, response.body()!!.gender)
            put(Constant.PREF_ADRESS, response.body()!!.address)
            put(Constant.PREF_EMAIL, response.body()!!.email)
            put(Constant.PREF_PHONE, response.body()!!.phone)
        }
        startActivity(Intent(this, HomeActivity::class.java))
        finish()
    } else {
        textViewResponse.text = "email or passord not available"
    }
})