Re: CustomId serialization

pieter gmail Mon, 25 Jun 2018 09:52:54 -0700

Ok, ah well I briefly searched for "@class" magic and did not find it.
I find Jackson's docs surprisingly bad.


Anyway no matter, it works for now.

Thanks
Pieter

On 25/06/2018 18:48, Stephen Mallette wrote:

I think - "think" being the key word - that Jackson parses that CLASS to
determine the deserializer to use and then hands your deserializer the
contents of the rest of the JSON (which is all the deserializers needs once
the right one is chosen).

On Mon, Jun 25, 2018 at 8:08 AM pieter gmail <[email protected]>
wrote:

Hi,

Just manage to get it to work, but not really sure whats going on.

So Sqlg's RecordId itself consist of a SchemaTable and a Long. Both
RecordId and SchemaTable has serialization code.

The part I don't quite get is that serializeWithType and deserialize is
not symmetrical.
Here is RecordId's serialization code.

          @Override
          public void serializeWithType(final RecordId recordId, final
JsonGenerator jsonGenerator,
                                        final SerializerProvider
serializerProvider, final TypeSerializer typeSerializer) throws
IOException, JsonProcessingException {

              jsonGenerator.writeStartObject();
jsonGenerator.writeStringField(GraphSONTokens.CLASS,
RecordId.class.getName());
              jsonGenerator.writeObjectField("schemaTable",
recordId.getSchemaTable());
              jsonGenerator.writeNumberField("id", recordId.getId());
              jsonGenerator.writeEndObject();
          }

          @Override
          public RecordId deserialize(final JsonParser jsonParser, final
DeserializationContext deserializationContext) throws IOException,
JsonProcessingException {
              org.apache.tinkerpop.shaded.jackson.core.JsonToken
jsonToken = jsonParser.nextToken();
              Preconditions.checkState(JsonToken.START_OBJECT == jsonToken);
              SchemaTable schemaTable =
deserializationContext.readValue(jsonParser, SchemaTable.class);
              jsonToken = jsonParser.nextToken();
Preconditions.checkState(org.apache.tinkerpop.shaded.jackson.core.JsonToken.FIELD_NAME

== jsonToken);
Preconditions.checkState("id".equals(jsonParser.getValueAsString()));
              jsonToken = jsonParser.nextToken();
              Preconditions.checkState(JsonToken.VALUE_NUMBER_INT ==
jsonToken);
              long id = jsonParser.getValueAsLong();
              jsonToken = jsonParser.nextToken();
Preconditions.checkState(org.apache.tinkerpop.shaded.jackson.core.JsonToken.END_OBJECT

== jsonToken);
              return RecordId.from(schemaTable, id);
          }

What happened to the GraphSONTokens.CLASS ?
I was expecting to have to read that also but somewhere I have lost the
flow.

Just to reiterate it is working now and all the tests are passing, so
its more of a information question.

Thanks
Pieter


On 25/06/2018 13:38, Stephen Mallette wrote:

I would think that you could write your own custom deserializer if you
needed to. That error doesn't give me any hints as to what might be wrong
exactly. I can't think of why that wouldn't work, but even with a little
refresh by looking at the code just now, my memory on GraphSON 1.0 is

fuzzy.

Maybe you could try to modify the working test in TinkerPop to include a
deserializer and see if you get a similar error for your efforts? Perhaps
that would help yield a clue?

On Mon, Jun 25, 2018 at 2:58 AM pieter gmail <[email protected]>
wrote:

Hi,

I am trying to upgrade Sqlg to 3.3.3 from 3.3.1.

The only tests that are failing are the io tests for graphson V1.

I see CustomId has a CustomIdJacksonSerializerV1d0 but not a
deserializer. Looks like Jackson is using reflection to instantiate the
CustomId and set its cluster and elementId.
Is this how it must be or can it work with a deserializer? Sqlg's
RecordId does not have default constructors.

For Sqlg I added the standard deserializer but it fails with.

org.apache.tinkerpop.shaded.jackson.databind.exc.InvalidTypeIdException:
Could not resolve type id 'org.umlg.sqlg.structure.SchemaTable' as a
subtype of [map type; class java.util.LinkedHashMap, [simple type, class
java.lang.Object] -> [simple type, class java.lang.Object]]: Not a

subtype

    at [Source: (ByteArrayInputStream); line: 1, column: 105] (through
reference chain: java.util.HashMap["id"])

       at

org.apache.tinkerpop.shaded.jackson.databind.exc.InvalidTypeIdException.from(InvalidTypeIdException.java:43)

at

org.apache.tinkerpop.shaded.jackson.databind.DeserializationContext.invalidTypeIdException(DeserializationContext.java:1628)

at

org.apache.tinkerpop.shaded.jackson.databind.DatabindContext.resolveSubType(DatabindContext.java:200)

at

org.apache.tinkerpop.shaded.jackson.databind.jsontype.impl.ClassNameIdResolver._typeFromId(ClassNameIdResolver.java:49)

at

org.apache.tinkerpop.shaded.jackson.databind.jsontype.impl.ClassNameIdResolver.typeFromId(ClassNameIdResolver.java:44)

at

org.apache.tinkerpop.shaded.jackson.databind.jsontype.impl.TypeDeserializerBase._findDeserializer(TypeDeserializerBase.java:156)

at

org.apache.tinkerpop.shaded.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer._deserializeTypedForId(AsPropertyTypeDeserializer.java:113)

at

org.apache.tinkerpop.shaded.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:97)

at

org.apache.tinkerpop.shaded.jackson.databind.deser.std.MapDeserializer.deserializeWithType(MapDeserializer.java:400)

at

org.apache.tinkerpop.shaded.jackson.databind.deser.impl.TypeWrappedDeserializer.deserialize(TypeWrappedDeserializer.java:68)

at

org.apache.tinkerpop.shaded.jackson.databind.DeserializationContext.readValue(DeserializationContext.java:759)

at

org.apache.tinkerpop.shaded.jackson.databind.DeserializationContext.readValue(DeserializationContext.java:746)

at

org.umlg.sqlg.structure.RecordId$RecordIdJacksonDeserializerV1d0.deserialize(RecordId.java:205)

Any ideas as to how I should implement this?

Thanks
Pieter

Re: CustomId serialization

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