deserialize list of strings into JSON in kotlin

June 7, 2023

I’m trying to deserialize the following string into JSON

val myList ="""{"user_id": "id1" ,"old_user_ids": "["id1,id2,id3"]", "status":"ACTIVE"}"""

I tried to deserialize using

val record = objectMapper.readValue(myList, UserRecord::class.java)

my data class looks like this

data class UserRecord(

    var user_id: String = "",
    var old_user_ids: List<String> = emptyList(),
    var status: String = ""

)

however, I’m getting the following error

Cannot construct instance of `java.util.ArrayList` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('[') at [Source: (String)"{"user_id": "id1" ,"old_user_ids": "["id1,id2,id3"]", "status":"ACTIVE"}";

I would appreciate if someone can point me to what I’m having wrong.

Output I’m trying to get is

{
 "user_id": "id1",
 "old_user_ids": ["id1","id2","id3"],
 "status":"ACTIVE"
}

>Solution :

Your JSON is invalid, it should be

{"user_id": "id1" ,"old_user_ids": ["id1","id2","id3"], "status":"ACTIVE"}

You have quotes around the [ ] array delimiters which is why it’s choking on that first character. Also your items in the array need quotes around each.