Thank you for your reply. Yep, my fault, it's just a mve, I actually
receive an 'Object o' which I need to serialize, that's why i doubt i could
annotate it as it is received from external source. I mean, i cannot
annotate fields of this object and would like to avoid modifying it as it
should be used further in the program. I don't need deserialization, just
serialization.
On Saturday, April 27, 2024 at 6:27:30 PM UTC+3 Mantas Gridinas wrote:
> Is @JsonSerialize still around? You could annotate fields with that
> annotation and jackson would delegate serializing those fields to that
> particular serializer. But your code would remain largely the same - you'd
> still need to check what to write depending on the field. I suppose you
> could cheat by having that field be some value interface type Foo, and
> implementations assigned to that field be FooMap or FooString, where
> FooString would have dedicated to string serializer. Deserializing on the
> other hand of such structures is painful, but nothing you couldn't handle
> with @JsonDeserialize.
>
> On Saturday, April 27, 2024 at 2:08:47 AM UTC Viktor Remennik wrote:
>
>> Hi there!
>>
>> I hope it's a simple question but I cannot find an answer myself. So,
>> asking for help.
>> I need to implement custom map serializer when mam mets some condition.
>> the problem is, that I need to replace the map with a primitive type, e.g.
>> string. As a simple example - when map conforms to some rule I want to
>> replace it with, let's say, string value. I understand there could be at
>> least one case when primitive, like string, cannot be used witout a key.
>> It's probably if the map is the root node.Maybe I could generate a key for
>> such a case?
>> Anyways, I cannot achieve it in any way I tried. Here's the MVE for my
>> question. I want to make it producing this:
>> {
>> "Second" : "Two",
>> "Third" : "magic string",
>> "First" : 1
>> }
>>
>> instead of default:
>>
>> {
>> "Second" : "Two",
>> "Third" : {
>> "Eleventh" : 11,
>> "Twelfth" : "12"
>> },
>> "First" : 1
>> }
>>
>> Here's the mve itself. Thank you!
>>
>>
>> public class MapParseTest
>>
>> {
>>
>> private final ObjectMapper mapper;
>>
>>
>> public MapParseTest()
>>
>> {
>>
>> mapper = new ObjectMapper();
>>
>> SimpleModule module = new SimpleModule();
>>
>> module.setSerializerModifier(new MyMapSerializerModifier());
>>
>> mapper.registerModule(module);
>>
>> }
>>
>>
>> public void doTest() throws JsonProcessingException
>>
>> {
>>
>> MyMap map1 = new MyMap();
>>
>> MyMap map2 = new MyMap();
>>
>>
>> map1.setName("shtame");
>>
>> map2.setName("magic name");
>>
>>
>> map1.put("First", 1);
>>
>> map1.put("Second", "Two");
>>
>> map1.put("Third", map2);
>>
>>
>> map2.put("Eleventh", 11);
>>
>> map2.put("Twelfth", "12");
>>
>>
>> String result =
>> mapper.writerWithDefaultPrettyPrinter().writeValueAsString(map1);
>>
>> System.*out*.println(result);
>>
>> }
>>
>>
>> public static void main(String[] args) throws JsonProcessingException
>>
>> {
>>
>> MapParseTest test = new MapParseTest();
>>
>> test.doTest();
>>
>> }
>>
>>
>> @Setter
>>
>> @Getter
>>
>> public static class MyMap extends HashMap<String, Object>
>>
>> {
>>
>> private String name;
>>
>> }
>>
>>
>> public static class MyMapSerializer extends JsonSerializer<MyMap>
>>
>> {
>>
>> private final JsonSerializer<Object> defaultSerializer;
>>
>>
>> public MyMapSerializer(JsonSerializer<Object> defaultSerializer)
>>
>> {
>>
>> this.defaultSerializer = defaultSerializer;
>>
>> }
>>
>>
>> @Override
>>
>> public void serialize(MyMap value,
>>
>> JsonGenerator gen,
>>
>> SerializerProvider provider) throws
>> IOException
>>
>> {
>>
>> String className = value.getName();
>>
>> if (className.equalsIgnoreCase("magic name"))
>>
>> {
>>
>> gen.writeString("magic string");
>>
>> } else
>>
>> {
>>
>> defaultSerializer.serialize(value, gen, provider);
>>
>> }
>>
>> }
>>
>> }
>>
>>
>> public static class MyMapSerializerModifier extends
>> BeanSerializerModifier
>>
>> {
>>
>> @Override
>>
>> public JsonSerializer<?> modifyMapSerializer(SerializationConfig
>> config,
>>
>> MapType mapType,
>>
>> BeanDescription
>> beanDesc,
>>
>> JsonSerializer<?>
>> serializer)
>>
>> {
>>
>> Class<?> type = beanDesc.getBeanClass();
>>
>> if (type.equals(MyMap.class))
>>
>> {
>>
>> return new MyMapSerializer((JsonSerializer<Object>)
>> serializer);
>>
>> }
>>
>> return serializer;
>>
>> }
>>
>> }
>>
>> }
>>
>>
>>
>>
>>
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