Map JSON field values to data class values - json

Question

I'm getting a JSON string that I'd like to clean up a bit and return less data. However, I'm having trouble figuring out how to get the values from the JSON and properly attach it to a data class I've created.
Here is the incoming JSON:
{
"continent": {
"code": "EU",
"names": {
"de": "Europa",
"ru": "Европа",
"pt-BR": "Europa",
"ja": "ヨーロッパ",
"en": "Europe",
"fr": "Europe",
"zh-CN": "欧洲",
"es": "Europa"
},
"geoname_id": 6255148
},
"country": {
"is_in_european_union": true,
"names": {
"de": "Frankreich",
"ru": "Франция",
"pt-BR": "França",
"ja": "フランス共和国",
"en": "France",
"fr": "France",
"zh-CN": "法国",
"es": "Francia"
},
"iso_code": "FR",
"geoname_id": 3017382
},
"city": {
"geoname_id": 2977058,
"names": {
"en": "Saint-Saulve",
"ru": "Сен-Сольв",
"zh-CN": "圣索尔沃"
}
},
"location": {
"accuracy_radius": 10,
"time_zone": "Europe/Paris",
"latitude": 50.3714,
"longitude": 3.5561
},
"postal": {
"code": "59880"
},
"registered_country": {
"is_in_european_union": true,
"names": {
"de": "Frankreich",
"ru": "Франция",
"pt-BR": "França",
"ja": "フランス共和国",
"en": "France",
"fr": "France",
"zh-CN": "法国",
"es": "Francia"
},
"iso_code": "FR",
"geoname_id": 3017382
},
"subdivisions": [
{
"names": {
"fr": "Hauts-de-France",
"en": "Hauts-de-France"
},
"iso_code": "HDF",
"geoname_id": 11071624
},
{
"names": {
"de": "Nord",
"en": "North",
"fr": "Nord",
"es": "Norte"
},
"iso_code": "59",
"geoname_id": 2990129
}
]
}
Data Classes:
data class locationData(val accuracyRadius: String = "", val timeZone: String = "", val latitude: String = "",
val longitude: String = "", val postalCode: String = "", val continent: Continent,
val country: Country, val city: City, val subdivision: Subdivision)
data class Continent(val code: String = "", val name: String = "", val geonameId: String = "")
data class Country(val isEU: Boolean = false, val name: String = "", val isoCode: String = "", val geonameId: String = "")
data class City(val name: String = "", val geonameId: String = "")
data class Subdivision(val name: String = "", val isoCode: String = "", val geonameId: String = "")
My sad attempt at iterating through the json and filtering out the pieces I don't want:
private fun cleanData(data: JsonNode): String {
data.fieldNames().forEachRemaining { field ->
println(field);
}
val result = data.filter { item ->
if (item.has("names")) {
return item.get("names").has("en"); item["name"] = item.get("names").get("en");
}
return item.toString();
}
return "";
/*val continent = {
"code" = data.get("continent").get("code"),
}*/
}
This is what my desired JSON output should be:
{
"accuracy_radius": 10,
"time_zone": "Europe/Paris",
"latitude": 50.3714,
"longitude": 3.5561,
"postalCode": "59880",
"continent": {
"code": "EU",
"name": "Europe",
"geonameId": 6255148
},
"country": {
"isEU": true,
"name": "France",
"isoCode": "FR",
"geonameId": 3017382
},
"city": {
"geonameId": 2977058,
"name": "Saint-Saulve",
},
"subdivisions": [
{
"name": "Hauts-de-France"
"isoCode": "HDF",
"geonameId": 11071624
},
{
"name": "North",
"isoCode": "59",
"geonameId": 2990129
}
]
}

Answer 1

I would suggest using Moshi (https://github.com/square/moshi/) and a custom adapter (see the examples on the github page) to filter/transform your data, when you read them into your data classes. If you have properly filled data objects, you should be able to write your desired JSON without any problems.