On Fri, Jun 18, 2021 at 7:30 AM Jon Harper <[email protected]> wrote:
>
> Hi, sorry for digging up this old post. This seems like not such a rare case.
> Is there a way to do it without any code (reusing existing standard
> converters) today ?
I am not 100% sure. There isn't anything specifically designed for
this; however, there's both `MapEntrySerialzier` and
`MapEntryDeserializer` so pieces are there that might allow composing
handling. Especially serialization could be composable.
But I have not tested if it possible to easily reuse these.
> I don't care if it's [ [ k, v], [ k, v] ...] or [ { key: k, value: v}, { key:
> k, value: v},...], or even [{ myname: k, myothername: v}, { myname: k,
> myothername: v}...]
> On deserialization, I don't care about what happens if the input has
> duplicates keys.
Right,but my guess is that there would be many others with different
preferences. :)
(that is, if a specific choice is introduced, the very first RFE would
be to add another alternative)
> I think it's worth documenting in the main site (maybe it is and I missed it
> ?). Actually I think that relying on toString() by default to serialize
> maps<Complex,X> is surprising, and maybe it's worth adding a global option to
> objectmapper to choose to convert all the maps<ComplexTypes, X> into lists of
> key value pairs ?
Given that JSON only allows String keys, the choice would typically be
either relying on `toString()` or throwing an exception; I could see
an option that would force throwing an exception to prevent surprises
about inability to deserialize such keys.
Now... I kind of do like the concept of transformation at a high
level. There would be challenges as (de)serializer type
parameterization would change for conversion; possibly this could be
done by reusing mechanism(s) used for Converters.
Besides this, there is the question of API for users: what I have
learned over time is that it makes a lot of sense to have multiple
levels of applicability; typically something like:
1. Global default
2. Per-type default
3. Per-property override(s)
Doing this is easiest with `@JsonFormat` settings (possibly including
JsonFormat.Feature on/off settings).
This assumes there'd be just a single way to translate Map into
Collection (JSON Object into JSON Array); further choices
would get a bit complicated.
I would be open to contributions here, if anyone is interested. I
probably will not have time myself to work on this in near future.
-+ Tatu +-
>
> Thanks in advance,
>
> On Thursday, June 25, 2015 at 8:41:01 PM UTC+2 [email protected] wrote:
>>
>> Right, not as well known as others. Couple of ways to use it:
>>
>> 1. Use of annotations, @JsonSerialize(converter=....),
>> @JsonDeserialize(converter=...) (either on type or for property)
>> 2. Use StdDelegatingSerializer (instantiate, or sub-class), register via
>> module.
>>
>> Converters were briefly mentioned along with 2.2 release (2 years ago) at:
>>
>> http://www.cowtowncoder.com/blog/archives/2013/08/entry_480.html
>>
>> -+ Tatu +-
>>
>>
>> On Thu, Jun 25, 2015 at 11:34 AM, Benson Margulies <[email protected]>
>> wrote:
>>>
>>> Converters are new to me :-)
>>>
>>> On Thu, Jun 25, 2015 at 2:33 PM, Tatu Saloranta <[email protected]> wrote:
>>>>
>>>> There isn't anything to do exactly that, but I think use of Converters
>>>> with intermediate type (Pair for List<Pair<K,V>>) might simplify the task.
>>>> Converter can then handle conversion from Map to List<Pair>, Jackson
>>>> serialize that using default mechanics.
>>>>
>>>> -+ Tatu +-
>>>>
>>>>
>>>> On Thu, Jun 25, 2015 at 8:57 AM, Benson Margulies <[email protected]>
>>>> wrote:
>>>>>
>>>>> Given a
>>>>>
>>>>> Map<somethingcomplex, value>
>>>>>
>>>>> I'd rather just have it serialize as
>>>>>
>>>>> [ [ k, v], [ k, v] ...]
>>>>>
>>>>> Is there a quick path here, or do I need a full custom setup?
>>>>>
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