How to convert json object with objects to json array with objects - kotlin

Question

I have a json object that looks like this.
{
"Items": {
"zzzz": {
"id": "zzzz",
"title": "qqqqqqq",
"notifications": []
},
"rrrrr": {
"id": "rrrrr",
"title": "rrrrrrrrrrrrrrrrrr",
"notifications": []
},
"eeeee": {
"id": "eeeee",
"title": "eeeeeeeeeeeeeeeeeeee",
"notifications": []
},
"wwww": null,
"dddddd": {
"id": "dddddd",
"title": "ddddddddddddddddddddddddd",
"notifications": []
},
"qqq": {
"id": "qqq",
"title": "qqqqqqqqqqqqqqqqqqqqqq",
"notifications": []
},
"rrrrrr": null
}
}
My data class:
data class Response(
val Items: List<Notification>
........)
data ckass Notification(
val id : String,
val title: String,
val notifications: List<...>,
I need a List with objects zzzz,rrrr and so on to get into the data class with val items. But I can't figure out how to convert the incoming json object to a json array
I wanted to use my own deserializer, but in my case it won't help because I use one instance of okhttp and retrofit for all requests. And also, a response always comes from the server in the form of:
"Items": {
//other request body
},
.....
}

Answer 1

I am not sure what deserializer you using. Here's a solution assuming Jackson, but maybe you can take the ideas from this if you are using Gson, etc.
The key idea is to use an intermediary object to deserialize into - a Map whose key values you ignore:
// your desired data classes
data class Response(
val items: List<Notification>,
)
data class Notification(
val id: String,
val title: String,
val notifications: List<Any>,
)
// an intermediary object
// I notice that some Notifications are null, hence the `?`
data class ResponseWithObjects(
#JsonProperty("Items") // this is needed for Jackson since I used a conventional variable name Kotlin side
val items: Map<String, Notification?>,
)
fun main(args: Array<String>) {
val actualResponse: ResponseWithObjects = TestUtils.deserialize("/test.json", ResponseWithObjects::class)
println(actualResponse)
val desiredResponse = Response(
items = actualResponse.items
.values.filterNotNull() // assuming you don't want the null notifications in the resultant array
.toList(),
)
println(desiredResponse)
}

Answer 2

To convert the given JSON object to a list of Notification objects, you can iterate over the key-value pairs in the "Items" object and create a Notification object for each non-null value. Here's some sample Kotlin code that demonstrates this:
val json = // the JSON object from your example
val itemsObject = json.getJSONObject("Items")
val notifications = mutableListOf<Notification>()
for (key in itemsObject.keys()) {
val item = itemsObject.getJSONObject(key)
if (item != null) {
val notification = Notification(
item.getString("id"),
item.getString("title"),
// add logic to parse notifications list here
)
notifications.add(notification)
}
}
val response = Response(notifications)
Note that you'll need to fill in the logic to parse the "notifications" list for each Notification object. If it's just an array of strings, you can use item.getJSONArray("notifications").toList() to get a list of strings.