I have the following data class as a data transfer object.

data class Continent(
    val continent: String,
    val countries: List<String>
)

so the JSON response is like below.

{
  "content": [
       {
           "continent": "Europe",
           "countries": [
              "France",
              "Germany"
           ]
       }
  ]
}

However, what I want to do is this:

{
  "content": [
        {
            "continent": "Europe",
            "country": "France"
        },
        {
            "continent": "Europe",
            "country": "Germany"
        }
  ]
}

I suppose there must be some kotlin collection functions to apply. Since the dto i wrote in the first code block is unable to be moderated, i have to apply collection functions on the service layer and make response dto accordingly.

Could you please let me know? Thanks in advance.

CodePudding user response：

data class Country(
    val continent: String,
    val country: String
)

fun List<ContinentResponse>.toCountries(): List<Country> =
    flatMap { r -> r.countries.map { country -> Country(r.continent, country) } }