Thought main reason for (de)seserializers is to provide such a low level
API to drive the JSONP by hand. The drawback is that user must use
Parser/Generator judiciously, because it is shared with JSONB runtime.
If we hide it completely, what methods would JsonbXXX interfaces have?
You cant do anything like getValue(String key), because once parser is
advanced it cannot move back. How about dropping JsonbXXX completly and
using JSONP Generator / Parser along with (De)SerializationContexts?
so deserializer method may look like:
T deserialize(JsonParser parser, //JSONP parser
DeserializationContext context) //has JSONB
mapper related methods
or
T deserialize(DeserializationContext context)
and add
JsonParser DeserializationContext#getParser() ?
According to generics part, did you mean that you would not be able to
resolve X if Deserializer is defined as MyDeserializer<MyPojo<X>> and
you want JSONB to pass a type of X into deserializer? So that
deserialize(...) method would be added by argument Type typeOfX ?
Thanks,
Roman
On 04/27/2016 03:16 PM, Romain Manni-Bucau wrote:
> 2016-04-27 15:12 GMT+02:00 Roman Grigoriadi
> <roman.grigoriadi_at_oracle.com <mailto:roman.grigoriadi_at_oracle.com>>:
>
> The difference between JsonbXXX and (De)SerContext is separation
> of processing logic, former has methods for driving JSONP, latter
> uses JSONB on top of it.
>
>
> I get it but the main purpose of the mapper if IMO to hide the parsing
> part so I would keep it but not as a main concept. That said I'm ok
> with that if I'm alone on this side ;).
>
> I don't get whats wrong with runtime type, for serialization. Have
> you noticed
>
> <T>T deserialize(TypeInfo<T> typeInfo);
>
> method? It will deserialize generic types.
>
>
> Sure but how do you do a new X() if you don't know X()? so the
> deserialize should get the static type somehow. <T> T deserialize() is
> an option but guess having the type in the signature allows to not
> instantiate it if not needed.
>
> Roman.
>
>
> On 04/27/2016 02:43 PM, Romain Manni-Bucau wrote:
>> Hi Roman,
>>
>> Few points but globally I think we move in the right direction!
>>
>> - "extends JsonXXX" I'd replace the extends by a delegation to
>> keep the fluent API typed (= return type is JsonbXXX and not
>> JsonXXX) and control over jsonb API.
>> - I don't fully get the difference between context and JsonbXXX,
>> i'd merge them (otherwise we would just using jsonp API but as
>> mentionned in previous point it has the drawback to loose all the
>> control.
>> - deserialization: we still need the type found by the runtime
>> (reflection) otherwise we can't allow generic serializers at all
>>
>>
>>
>> Romain Manni-Bucau
>> @rmannibucau
>> http://www.tomitribe.com
>> http://rmannibucau.wordpress.com
>> https://github.com/rmannibucau
>>
>> 2016-04-27 14:33 GMT+02:00 Roman Grigoriadi
>> <roman.grigoriadi_at_oracle.com>:
>>
>> Hi experts,
>>
>> following previous discussions for including de/serializers
>> in JSONB along with adapters, here is proposal for interfaces
>> in JSONB API:
>>
>> public interface JsonbSerializer<T> {void serialize(T obj, JsonbGenerator generator, SerializationContext ctx);
>> }
>>
>> public interface JsonbDeserializer<T> {T deserialize(JsonbParser parser, DeserializationContext ctx);
>> }
>>
>> /** * Jsonb decorator for JSONP generator.Includes validation
>> for writing END_OBJECT / END_ARRAY checking level of closed
>> JSON structure. * Helper generator methods may be added here.
>> */ public interface JsonbGeneratorextends JsonGenerator {
>> }/** * Jsonb decorator for JSONP parser.Includes validation of
>> cursor position after leaving deserializer, alters hasNext()
>> behavior. * Helper parser methods may be added here. */ public interface JsonbParserextends JsonParser {
>> }
>>
>> public interface SerializationContext {
>>
>> /** * Serializes arbitrary object to JSON with JSONB, using
>> current {_at_link javax.json.stream.JsonGenerator} instance.*/ <T>void serialize(String key,T object);
>>
>> /** * Checks if type is supported for conversion to string by
>> JSONB.*/ boolean supportsConversion(Class<?> clazz);
>>
>> /** * Converts string value into provided type. String value
>> has to be single JSON value, not a part * of a JSON document
>> representing JSON object / array.*/ <T> String convertDefault(T obj);
>> }public interface DeserializationContext {
>>
>> /** * Deserializes JSON stream into instance of provided
>> class with JSONB using {_at_link javax.json.stream.JsonParser}.
>> * JsonParser cursor have to be at KEY_NAME before
>> START_OBJECT to call this method.*/ <T>T deserialize(Class<T> clazz);
>>
>> /** * Similar as above for generic types.*/ <T>T deserialize(TypeInfo<T> typeInfo);
>>
>> /** * Checks if type is supported for conversion from string
>> by JSONB.*/ boolean supportsConversion(Class<?> toClass);
>>
>> /** * Converts string value into provided type. String value
>> has to be single JSON value, not a part * of a JSON document
>> representing JSON object.*/ <T>T convertDefault(Class<T> toClass, String value);
>>
>> }
>>
>> JsonbParser / JsonbGenerator objects are supposed to decorate JSONP behavior.
>> For example in case of JsonParser hasNext() call may be altered to return false if currently deserialized object has ended in the stream. Helper methods (like nextKey(String), isKey(String), etc for json processing may be included here.
>>
>> In addition to Generators/Parsers, (De)SerializationContexts are intended to provide JSONB functionality such as (de)serialization of arbitrary java types, conversion to/from string of known types such are Dates or Numbers.
>> We could also add some insight into introspected customization from JSONB annotations based on a Class and property name.
>>
>> An example of how implementation of such (de)serializer may look:
>>
>> public class CrateSerializerimplements JsonbSerializer<Crate> {
>>
>> @Override public void serialize(Crate obj, JsonbGenerator generator, SerializationContext ctx) {
>> generator.write("crateStr","REPLACED");
>> ctx.serialize("crateInner", obj.crateInner);
>> ctx.serialize("crateInnerList", obj.crateInnerList);
>> generator.write("date-converted", dateValue);
>> }
>> }
>>
>> public class CrateDeserializerimplements JsonbDeserializer<Crate> { @Override public Crate deserialize(JsonbParser jsonParser, DeserializationContext ctx) {
>> Crate crate =new Crate();
>>
>> while (jsonParser.hasNext()) {
>> JsonParser.Event next = jsonParser.next();
>>
>> if (next.equals(JsonParser.Event.KEY_NAME) && jsonParser.getString().equals("crateInner")) {
>> //invokes JSONB processing for a CrateInner as a root type
>> with "shared" instance of JsonParser //may invoke other
>> serializer or adapter instances inside crate.crateInner = ctx.deserialize(CrateInner.class);
>> next = jsonParser.next();
>> }
>> if (next.equals(JsonParser.Event.KEY_NAME) && jsonParser.getString().equals("crateInnerList")) {
>> //invokes JSONB processing for a List<CrateInner> as a root
>> type with "shared" instance of JsonParser //may invoke other
>> serializer or adapter instances inside crate.crateInnerList = ctx.deserialize(new TypeToken<List<CrateInner>>() {});
>> }
>> if (next.equals(JsonParser.Event.KEY_NAME) && jsonParser.getString().equals("date-converted")) {
>> jsonParser.next();
>> //don't have context of processing here, no annotation
>> customizations applied. Date converted = ctx.convertDefault(Date.class, jsonParser.getString());
>> crate.date = converted;
>> }
>>
>> }
>>
>> return crate;
>> }
>> }
>>
>>
>> @Romain, this is similar to what you have suggested first time.
>>
>> In addition JsonbAdapters may be used to convert From / To JsonObject or JsonArray, but auto conversion between unknown JavaTypes and JsonStructure will not be supported, at least in first version of a spec.
>> WDYT?
>>
>> Thanks,
>> Roman
>>
>>
>
>