Deserializing JSON objects with variable structure, GSON - json

Question

I'm trying to deserialize JSON with the following structure using GSON:
"FKeyColumn": [{
"ForeignKeyColumns": {
"Id": "Id"
},
"ReferenceTable": "Expense_Group_Configurations"
}],
"FKeyColumn": [{
"ForeignKeyColumns": {
"Vid": "Id"
},
"ReferenceTable": "Expense_Group_Configurations"
}]
...
I'm not sure how to structure my ForeignKeyColumns class though, since the JSON object it represents contains arbitrary key-value pairings (there's no set structure aside from the object always being named ForeignKeyColumns). How can I parse this with GSON?

Answer 1

It required a custom deserializer for FKeyColumn objects:
public class FKeyColumnDeserializer implements JsonDeserializer<FKeyColumn> {
public FKeyColumn deserialize(final JsonElement json, final Type typeOfT, final JsonDeserializationContext context)
throws JsonParseException {
final JsonArray jsonFKArray = json.getAsJsonArray();
final FKeyColumn fkc = new FKeyColumn();
for (int i = 0; i < jsonFKArray.size(); i++) {
final JsonObject fkObject = (JsonObject) jsonFKArray.get(i);
final String ReferenceTable = fkObject.get("ReferenceTable").getAsString();
final JsonObject ForeignKeyColumns = (JsonObject) fkObject.get("ForeignKeyColumns");
Set<Entry<String, JsonElement>> entrySet = ForeignKeyColumns.entrySet();
for(HashMap.Entry<String, JsonElement> entry : entrySet){
fkc.fkRefTableMap.put(entry.getKey(), ReferenceTable);
}
}
return fkc;
}
}