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[jsonb-spec users] [jsr367-experts] Re: Re: Re: Re: Re: Re: Re: JSONB De/Serializers proposal

From: Eugen Cepoi <cepoi.eugen_at_gmail.com>
Date: Tue, 10 May 2016 10:55:35 -0700

About using writeName followed by writeXXX: it is prevented by the api. For
example the writeValueXXX without the name as parameter can be called only
once in the root context or in an array,
https://github.com/json-processing-inofficial/jsonp/blob/master/api/src/main/java/javax/json/stream/JsonGenerator.java#L185

Indeed we could have a wrapper that does this logic and then does the
respective calls to the backed JsonGenerator, but I am not a big fan of
this option. It adds another api and feels like a disagreement with what
has been done in jsonp (be it good or bad), which I really see as the low
level streaming pendent of jsonb.




2016-05-10 7:30 GMT-07:00 Romain Manni-Bucau <rmannibucau_at_tomitribe.com>:

>
> 2016-05-10 15:51 GMT+02:00 Roman Grigoriadi <roman.grigoriadi_at_oracle.com>:
>
>>
>>
>> On 05/10/2016 03:37 PM, Romain Manni-Bucau wrote:
>>
>>
>> 2016-05-10 15:26 GMT+02:00 Roman Grigoriadi <roman.grigoriadi_at_oracle.com>
>> :
>>
>>>
>>>
>>> On 05/10/2016 08:14 AM, Romain Manni-Bucau wrote:
>>>
>>> Ok, let step back. Before all *technically* I fully agree with you. Why
>>> I defend a different position is from my experience a lot of people will
>>> not be able to use such an API so i'm trying to ensure our API is adopted
>>> whatever use case we support.
>>>
>>> Whats wrong with JsonParser API from user perspective? If JsonStructure
>>> is needed instead of event driven api, it can be provided by mapper API (as
>>> Eugene mentioned). JsonParser will be at START_OBJECT position when passed
>>> to deserializer, so user can get JsonStructure for whole deserializer
>>> root/return type. Furthermore, according to JSONP master branch, looks like
>>> there will be methods for getting JsonArray/JsonObject directly on
>>> JsonParser since JSONP 1.1 release.
>>>
>>>
>>>
>> Proposal is just to add an abstract child already doing
>> context.deserialize(JsonObject.class, parser) and giving as parameter
>> the JsonObject instead of the parser. Making it direct and not requiring
>> users to look for this or to know they have to pass JsonObject.class as
>> parameter is good enough.
>>
>> But wouldn't it be redundant after JSONP 1.1, which has those already in
>> JsonParser?
>>
>>
>>
>>
> Maybe but it doesn't cost much and makes it an easier entry point for
> several users so I think it does worth it.
>
>
>> Secondly the fact jsonp doesnt support writeKey()writeValue() doesnt
>>> prevent us to do it (we actually do since we have the key before the value
>>> in the mapper model ;)).
>>>
>>> Didn't get this one, we do writeStartObject(String key), and
>>> writeEndObject() in the mapper.
>>>
>>>
>> In the API or the impl? Globally point is we can support a single
>> serialize method as mentionned by Eugen.
>>
>> Ok, I missed the point.
>>
>>
>>
>>>
>>> It means I think we can go for Eugen proposal BUT to support my case too
>>> we would need a subclass/abstract impl giving the JsonReader (read(parser,
>>> Object) doesn't work, see polymorphism thread).
>>>
>>> Would it be a good compromise?
>>>
>>>
>>>
>>> Romain Manni-Bucau
>>> @rmannibucau
>>> http://www.tomitribe.com
>>> http://rmannibucau.wordpress.com
>>> https://github.com/rmannibucau
>>>
>>> 2016-05-10 0:46 GMT+02:00 Eugen Cepoi < <cepoi.eugen_at_gmail.com>
>>> cepoi.eugen_at_gmail.com>:
>>>
>>>> Ahh damn I remember now... in jsonp we have a separate methods to be
>>>> used inside objects which takes the key and others without the key, but you
>>>> can't first write the key and then write the value...which sucks. I should
>>>> have insisted more on that :p
>>>>
>>>> So in short my comment is irrelevant as I was assuming that we have
>>>> writeName+writeValue methods in JsonGenerator...so yeah in this case there
>>>> is no choice, we need serialize methods that take a key and another that
>>>> doesn't... :(
>>>>
>>>> 2016-05-09 15:22 GMT-07:00 Dmitry Kornilov <
>>>> <dmitry.kornilov_at_oracle.com>dmitry.kornilov_at_oracle.com>:
>>>>
>>>>>
>>>>> I also think that passing jsonp parser/generator as an argument is OK.
>>>>>> The question here is that we are forcing implementations to use
>>>>>> parser/generator. What if (as Romain mentioned somewhere in this thread)
>>>>>> some implementations will use reader/writer as a parsing mechanism? Shall
>>>>>> we consider this option? Folks, I need you opinion here.
>>>>>>
>>>>>>
>>>>> JsonReader/writer just deal with the full dom structures, to get a dom
>>>>> structure one could simply do ctx.deserialize(JsonObject.class, stream).
>>>>> So I think it is just fine and is the right thing to do: use the low
>>>>> level jsonp api.
>>>>>
>>>>>
>>>>> Agree.
>>>>>
>>>>> But there is another use case. What if we have a list inside an object
>>>>>> we are serializing.
>>>>>>
>>>>>> public class Create {
>>>>>> public List items;
>>>>>> }
>>>>>>
>>>>>> For some reason we don’t want to serialize items list using
>>>>>> context.serialize(“items”, crate.items, generator).
>>>>>> We want to serialize each item manually in a cycle.
>>>>>>
>>>>>> generator.writeStartArray();
>>>>>> for (Object item in crate.items) {
>>>>>> // Ooops! We don’t have a method to write an object without a key in
>>>>>> SerializationContext
>>>>>> // It should be something like this
>>>>>> *context.serialize(item, generator); // This is a new method to add I
>>>>>> was talking about*
>>>>>> }
>>>>>> generator.writeEnd();
>>>>>>
>>>>>>
>>>>> Not sure if I followed everything (I have been busy with other things
>>>>> lately), but IMO the context should not provide different methods for
>>>>> arrays, objects etc. Only one that takes an object, a generator and
>>>>> eventually a type (if we want to allow a user to say serialize object of
>>>>> type B but using his super type A). One could pass to it arrays, lists,
>>>>> pojos, primitives, whatever he wants and it will get serialized/deser using
>>>>> the registered serializers for that type.
>>>>> I hope I am not adding more confusion here…if you want some code
>>>>> examples let me know.
>>>>>
>>>>>
>>>>> Yes, I think we have some misunderstanding here. Below I copied our
>>>>> latest version of SerializationContext interface to make it clear. As you
>>>>> see there are no methods for arrays, lists, etc. The method I was talking
>>>>> about above is marked bold.
>>>>>
>>>>> public interface SerializationContext {
>>>>>
>>>>> /**
>>>>> * Serializes arbitrary object to JSON, using current {_at_link
>>>>> javax.json.stream.JsonGenerator} instance.
>>>>> *
>>>>> * @param key JSON key name
>>>>> * @param object object to serialize
>>>>> * @param generator JSONP generator to serialize with
>>>>> * @param <T> Type of serialized object
>>>>> */
>>>>> <T> void serialize(String key, T object, JsonGenerator generator);
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> * /** * Serializes arbitrary object to JSON, using current
>>>>> {_at_link javax.json.stream.JsonGenerator} instance. * * @param
>>>>> object object to serialize * @param generator JSONP generator to
>>>>> serialize with * @param <T> Type of serialized object */ <T>
>>>>> void serialize(T object, JsonGenerator generator);*
>>>>>
>>>>> /**
>>>>> * Converts string value into provided type. String value has to
>>>>> be single JSON value, not a part
>>>>> * of a JSON document representing JSON object.
>>>>> *
>>>>> * @param obj object to convert to string
>>>>> * @param generator JSONP generator to serialize with
>>>>> * @param <T> type of object
>>>>> *
>>>>> * @return converted string value
>>>>> * @throws javax.json.bind.JsonbException if conversion of given
>>>>> type is not supported
>>>>> */
>>>>> <T> String convertDefault(T obj, JsonGenerator generator);
>>>>> }
>>>>>
>>>>> Thanks,
>>>>> Dmitry
>>>>>
>>>>>
>>>>
>>>
>>>
>>
>>
>