Allow @JsonSerialize to be used on @Controller methods [SPR-13369]

[spring-projects-issues]

Phil Webb opened SPR-13369 and commented

Similar to the @JsonView support it would be helpful if the @JsonSerialize annotation could be used on a @Controller method.

Possibly raised before in #13935

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Issue Links:

• MappingJacksonJsonView: Recognize Jackson Annotations (ex @JsonSerialize) when returning objects from methods annotated with @ResponseBody [SPR-9297] #13935 MappingJacksonJsonView: Recognize Jackson Annotations (ex @JsonSerialize) when returning objects from methods annotated with @ResponseBody

[spring-projects-issues]

Sébastien Deleuze commented

That would be indeed useful, but I am not sure Jackson API allows us to specify a JsonSerializer to use just for serializing a specific value.

We currently use writerWithView(Class<?> serializationView) or writer(FilterProvider filterProvider) to get an ObjectWriter instance specific to the value to serialize, but it seems there is no equivalent for JsonSerializer and ObjectWriter itself does not seem to allow to customize that.

That makes me think that even if you can annotate POJOs with @JsonSerialize, that's still something that remains mostly static for Jackson, not dynamic like @JsonView or filters ...

Any thoughts ?

[spring-projects-issues]

Phil Webb commented

Perhaps a custom com.fasterxml.jackson.databind.JsonSerializable could be passed to the ObjectWriter? It could wrap the the response object, create the JsonSerializer instance then from the annotation and delegate the serialize... methods.

[spring-projects-issues]

Dmitry F. commented

it would be best future

[spring-projects-issues]

Jon Edvardsson commented

I am looking for the same feature. Infact, I think it can be done quite easily by just some minor tweaks of the existing code.

Consider that we add support for JsonSerialize.as, then we need to add a field writerFor in MappingJacksonValue. We need to create a new class JsonSerializeResponseBodyAdvice similar to the JsonViewResponseBodyAdvice that copies this info over to MappingJacksonValue.

Then finally update the AbstractJackson2HttpMessageConverter#writeInternal to:

// ... code left out before
        ObjectWriter objectWriter;
        if (filters != null) {
            objectWriter = this.objectMapper.writer(filters);
        }
        else if (writerFor != null) {
            objectWriter = this.objectMapper.writerFor(writerFor);
        }
        else if (javaType != null && javaType.isContainerType()) {
            objectWriter = objectWriter.withType(javaType);
        else {
            
            objectWriter = this.objectMapper.writer();
        }

        if (serializationView != null) {
            objectWriter = objectWriter.withView(serializationView);
        }
        objectWriter.writeValue(generator, value);
//... code left out after

[spring-projects-issues]

Bulk closing outdated, unresolved issues. Please, reopen if still relevant.