How to use JsonIdentityInfo with this lib?

[bognari]

Hi I have an Object like this:

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator::class , property= "uri")
class Entry(val uri: String) {
    @JsonIdentityReference(alwaysAsId = true)
    var contains : MutableSet<Entry> = Collections.synchronizedSet(HashSet())
}

When I use the JacksonMapper from the KMongoConfiguration I get an valid JSON in with "contains" contains only the URIs from the containing entries.
But when I try to Insert it into the MongoDB I get this Exception:

Caused by: java.lang.IllegalStateException: XXX has to be class org.bson.types.ObjectId
	at org.litote.kmongo.jackson.KMongoBsonFactory$KMongoBsonGenerator.writeObjectId(KMongoBsonFactory.kt:49)
	at com.fasterxml.jackson.databind.ser.impl.WritableObjectId.writeAsField(WritableObjectId.java:67)
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase._serializeWithObjectId(BeanSerializerBase.java:627)
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:148)
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480)

If I change the Object to this I get the exception also...

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator::class , property= "_id")
class Entry(uri: String) {
    @BsonId 
    val _id: Id<Entry> = StringId(uri)
    @JsonIdentityReference(alwaysAsId = true)
    var contains : MutableSet<Entry> = Collections.synchronizedSet(HashSet())

As far as I can see the StringID Object are changed to a String inside Jackson

public void writeAsField(JsonGenerator gen, SerializerProvider provider,
            ObjectIdWriter w) throws IOException
    {
        idWritten = true;

        // 03-Aug-2013, tatu: Prefer Native Object Ids if available
        if (gen.canWriteObjectId()) {
            // Need to assume String(ified) ids, for now... could add 'long' variant?
            gen.writeObjectId(String.valueOf(id));
            return;
        }
        
        SerializableString name = w.propertyName;
        if (name != null) {
            gen.writeFieldName(name);
            w.serializer.serialize(id, gen, provider);
        }
    }

[zigzago]

Well... KMongo did not support to generate id as String with @JsonIdentityInfo. This is fixed in snapshot.
Here is a way to generate an Id with the fix:

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator::class, property = "uri")
class Entry() {

        constructor(uri:String) : this() {
            this.uri = uri
        }

        lateinit var uri: String

        @JsonIdentityReference(alwaysAsId = true)
        var contains: MutableSet<Entry> = Collections.synchronizedSet(HashSet())

    }

There is a bug in jackson-module-kotlin lib, so you can't place the id in primary constructor.

With this solution, the bson in mongo looks like this:

{"_id": "http://litote.org/kmongo", "uri": "http://litote.org/kmongo", "contains": []}

HTH

[bognari]

Thanks for the fast response and sorry for my bad mood yesterday.
I tested the fix today and it works as described. Thank you very much.