CODEWITHSUNDEEP
javajsonspringjackson
Amine Hakkou
Amine Hakkou

Reputation: 574

Deserializing JSON to polymorphic object model using @JsonTypeInfo & @JsonSubTypes not working?

I am trying to have a REST endpoint create a subtype of Widget when POSTing to it,

here is the base class for all Widgets

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "widgetType")
@JsonSubTypes({
        @JsonSubTypes.Type(value = TextWidget.class, name = WidgetType.Constants.TEXT),
        @JsonSubTypes.Type(value = ImageWidget.class, name = WidgetType.Constants.IMAGE),
        @JsonSubTypes.Type(value = IndicatorWidget.class, name = WidgetType.Constants.INDICATOR),
        @JsonSubTypes.Type(value = MapWidget.class, name = WidgetType.Constants.MAP),
        @JsonSubTypes.Type(value = ChartWidget.class, name = WidgetType.Constants.CHART)
})
@Data
@Slf4j
public abstract class Widget {
...
}

this is the WidgetType enum:

public enum WidgetType {
    TEXT(Constants.TEXT),
    IMAGE(Constants.IMAGE),
    INDICATOR(Constants.INDICATOR),
    MAP(Constants.MAP),
    CHART(Constants.CHART);
    private final String type;
    WidgetType(final String type) {
        this.type = type;
    }

    public static class Constants {
        public static final String TEXT = "TEXT";
        public static final String IMAGE = "IMAGE";
        public static final String INDICATOR = "INDICATOR";
        public static final String MAP = "MAP";
        public static final String CHART = "CHART";
    }
}

and this is my Spring endpoint:

@RequestMapping(method = RequestMethod.POST)
public Optional<Widget> createWidget(@Valid final Widget widget) {
    ...
    }

when hitting that endpoint it throws this exception:

{
  "timestamp": 1493029336774,
  "status": 500,
  "error": "Internal Server Error",
  "exception": "org.springframework.beans.BeanInstantiationException",
  "message": "Failed to instantiate [....models.Widget]: Is it an abstract class?; nested exception is java.lang.InstantiationException",
  "path": "...."
}

skimming through few solutions for my problem, I might have to manually register the subtypes, I might be wrong, but I think there must be a way to make it work with annotations, maybe I am missing something?

Upvotes: 2

Views: 819

Answers (1)

Amine Hakkou
Amine Hakkou

Reputation: 574

problem solved, I was annotating my classes with Jackson annotation and forgot that I was sending multipart POST requests, that wasn't even going to Jackson. The solution is as simple as this:

@RequestMapping(method = RequestMethod.POST)
public Optional<Widget> createWidget(@RequestBody final Widget widget) {
    ...
    }

Upvotes: 3

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