I see.
I could get what I want with such ways.
Thanks for quick response.
2016年10月8日土曜日 2時52分18秒 UTC+9 Tatu Saloranta:
>
> So, what happens is that while you think you are giving a
> List<ExampleContent> (or List<AbstractContent>), what runtimes sees is a
> List<? extends Object>. Since `Object` has no `@JsonTypeInfo`, no type is
> included.
>
> You have been tripped by Java Type Erasure. Also, my general suggestion is
> to NEVER EVER use generic type as the root type, but always use a
> non-generic type. There are multiple ways to do that. Like:
>
> 1. Always use a POJO to contain Lists, Maps (wrapper)
> 2. Sub-class Lists, Maps:
>
> public class ExampleList extends ArrayList<AbstractContent> { }
>
> because this does retain type information
>
> But there is also one way to make generic root type to work (although with
> caveats)
>
> 1. Use `ObjectWriter`, specifying actual type, without erasure:
>
> mapper.writerFor(new TypeReference<List<AbstractContent>>() {
> }).writeValueAsString(list);
>
> in this case you may hit other problems, since type is now fixed for
> content as well, so this may fail for some type definitions.
>
> -+Tatu +-
>
>
> On Thu, Oct 6, 2016 at 5:53 PM, krrrr38 <[email protected] <javascript:>>
> wrote:
>
>> Hi. I use jackson-databind 2.8.3.
>>
>> I want to serialize value with `@JsonTypeName`. When serialize with
>> `List`, the property value is not shown.
>>
>> public class Main {
>> public static void main(String[] args) throws Exception {
>> ObjectMapper om = new ObjectMapper();
>> System.out.println(om.writeValueAsString(new ExampleContent()));
>> System.out.println(om.writeValueAsString(Arrays.asList(new
>> ExampleContent())));
>> }
>>
>> @JsonTypeInfo(
>> use = JsonTypeInfo.Id.NAME,
>> include = JsonTypeInfo.As.PROPERTY,
>> property = "type",
>> visible = true
>> )
>> @JsonSubTypes({
>> @JsonSubTypes.Type(ExampleContent.class)
>> })
>> abstract static public class AbstractContent {
>> }
>>
>> @JsonTypeName("text")
>> public static class ExampleContent extends AbstractContent {
>> }
>> }
>>
>>
>> result
>>
>> {"type":"text"}
>> [{}]
>>
>>
>> expected?
>>
>> {"type":"text"}
>> [{"type":"text"}]
>>
>> Do I need to add more annotation or something?
>>
>> Regargs.
>>
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>
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