I just added @JsonAnyGetter to the wrapper class and now when I write
mapper.writeValueAsString(wrapper), it gives the expected output. I don't
understand why but it just works!
@JsonAnyGetter
@JsonSerialize(contentUsing = ItemRowSerializer.class)
private Map<RecordDomain, ItemRow> foo;
On Monday, December 24, 2018 at 4:56:27 PM UTC-8, Tatu Saloranta wrote:
>
> On Fri, Dec 21, 2018 at 2:30 PM matt Smith <[email protected]
> <javascript:>> wrote:
> >
> > In the above case, I called
> `mapper.writeValueAsString(wrapper.getFoo());`
> >
> > I changed to the following (moved to annotation to the field level).
> when I write using `mapper.writeValueAsString(wrapper)`, I see the
> expected serialization applied. However, extra node "foo" is added at root.
> is there a way to not have it?
>
> No, if applied as content serializer, Map serializer will produce
> wrapping.
> You would need custom serializer that just serializes entries and not
> enclose them within START_OBJECT / END_OBJECT.
>
> -+ Tatu +-
>
> > public class Wrapper {
> >
> >
> > @JsonSerialize(contentUsing = ItemRowSerializer.class)
> > private Map<RecordDomain, ItemRow> foo;
> >
> >
> > public Wrapper(Map<RecordDomain, ItemRow> fooz) {
> > foo = new HashMap<>(fooz);
> > }
> >
> >
> > public Map<RecordDomain, ItemRow> getFoo() {
> > return foo;
> > }
> >
> >
> > public void setFoo(Map<RecordDomain, ItemRow> foo) {
> > this.foo = foo;
> > }
> > }
> >
> >
> > On Friday, December 21, 2018 at 1:52:41 PM UTC-8, matt Smith wrote:
> >>
> >> even moving annotation to the field did not work.
> >> Note I have annotated class ItemRow class which ofcourse i can't since
> it is part of legacy code.
> >>
> >> On Friday, December 21, 2018 at 12:49:21 PM UTC-8, Tatu Saloranta
> wrote:
> >>>
> >>> On Fri, Dec 21, 2018 at 12:06 AM matt Smith <[email protected]>
> wrote:
> >>> >
> >>> > so I have made this wrapper and annotated getter with
> @JsonSerialize. however, I do not see it being applied. what is wrong here?
> >>>
> >>> That looks like it should work. If not, a unit test & issue would make
> sense.
> >>>
> >>> -+ Tatu +-
> >>>
> >>> >
> >>> > public class Wrapper {
> >>> >
> >>> >
> >>> > private Map<RecordDomain, ItemRow> foo;
> >>> >
> >>> >
> >>> > public Wrapper(Map<RecordDomain, ItemRow> fooz) {
> >>> > foo = new HashMap<>(fooz);
> >>> > }
> >>> >
> >>> >
> >>> > @JsonSerialize( contentUsing = ItemRowSerializer.class)
> >>> > public Map<RecordDomain, ItemRow> getFoo() {
> >>> > return foo;
> >>> > }
> >>> >
> >>> >
> >>> > public void setFoo(Map<RecordDomain, ItemRow> foo) {
> >>> > this.foo = foo;
> >>> > }
> >>> > }
> >>> >
> >>> >
> >>> > On Thursday, December 20, 2018 at 1:25:59 PM UTC-8, Tatu Saloranta
> wrote:
> >>> >>
> >>> >> On Thu, Dec 20, 2018 at 11:22 AM matt Smith <[email protected]>
> wrote:
> >>> >> >
> >>> >> > I encountered a case where class level JsonSerializable
> annotation does not require registration with Simple Module but method
> level does.
> >>> >>
> >>> >> Hmmh. This seems odd, let's see.
> >>> >>
> >>> >> > Here is the example I tried
> >>> >> >
> >>> >> > @JsonSerialize(using = ItemRowSerializer.class )
> >>> >> > private ItemRow tes
> >>> >> > tItem(){
> >>> >> > return new ItemRow("abc", Arrays.asList("item1",
> "item2", "item3"));
> >>> >> > }
> >>> >> >
> >>> >> >
> >>> >> > I test it out like this
> >>> >> >
> >>> >> >
> >>> >> > String jsonResult = new
> ObjectMapper().writeValueAsString(testItem());
> >>> >> > System.out.println(jsonResult);
> >>> >> >
> >>> >> > I noticed that jsonString did not serialize using
> ItemRowSerializer.
> >>> >>
> >>> >> Ah. No, it won't. Jackson does not see you calling the method;
> Jackson
> >>> >> sees the object you pass, which was returned by the method. There
> is
> >>> >> no linkage there: Jackson can only introspects classes you pass to
> it.
> >>> >>
> >>> >> > However, when I did this, it gave the expected jsonString
> >>> >> >
> >>> >> >
> >>> >> > SimpleModule module = new SimpleModule()
> >>> >> > module.addSerializer(ItemRowSerializer.class)
> >>> >> > mapper.register(module);
> >>> >> > String jsonResult = new
> ObjectMapper().writeValueAsString(testItem());
> >>> >> > System.out.println(jsonResult);
> >>> >> >
> >>> >> >
> >>> >> > On the otherhand, if I had my ItemRow class annoated with
> @JsonSerializable, there was no need with module at all.
> >>> >>
> >>> >> I think you mean `@JsonSerialize` here (there is interface type
> >>> >> `JsonSerializable`, but no annotation).
> >>> >>
> >>> >> > i.e
> >>> >> >
> >>> >> > @JsonSerializable(using = ItemRowSerailizer
> >>> >> > public class ItemRow<T> {...}
> >>> >> >
> >>> >> >
> >>> >> > Since I am passing this serialized object over the wire, I do not
> prefer to write to mapper and send string representation across.
> >>> >> >
> >>> >> > how would I go about getting method level annotation working
> without module registration?
> >>> >>
> >>> >> Method level annotations only work when property is accessed via
> >>> >> method (or field) in question.
> >>> >>
> >>> >> So if you had something like:
> >>> >>
> >>> >> public class Rows
> >>> >> @JsonSerialize(using = .... )
> >>> >> public ItemRow<Type> getRows() { ... }
> >>> >> }
> >>> >>
> >>> >> and serialized an instance of `Rows`, serializer would be found.
> But
> >>> >> for root values, there is no such reference.
> >>> >>
> >>> >> On related note, I strongly recommend always using a wrapper type
> >>> >> around generic values, so that root value is never of generic type.
> >>> >> Reason for this is that Java Type Erasure will often cause problems
> if
> >>> >> attempting to pass an instance of generic type -- so Jackson can
> not
> >>> >> detect intended type (all it sees is type variable from class
> >>> >> declaration).
> >>> >>
> >>> >> So, attempts to serialize, say, Row<T>, will be seen as `Row<?>`,
> and
> >>> >> possibly (although not always) cause issues in finding handlers for
> >>> >> the type -- for example, if value type has annotations, they may
> not
> >>> >> be visible.
> >>> >>
> >>> >> -+ Tatu +-
> >>> >
> >>> > --
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