CODEWITHSUNDEEP
javajsonjacksondeserializationjson-deserialization
ADK
ADK

Reputation: 513

Jackson use custom JSON deserializer with default

All code below is simplified version. I have JSON structure:

{
    "content" : {
        "elements" : [ {
            "type" : "simple"
            },
            {
            "type" : "complex", 
            "content" : {
                "elements" : [ {
                    "type" : "simple"
                },
                {
                    "type" : "simple"
                },
                {
                    "type" : "complex",
                    "content" : {
                      ---- /// ----
                    }
                } ] 
            } 
        } ] 
    }
}

I use Jackson lib for deserialization, and i am trying to implement a kind of "mix" custom with default deserializers. I want Element object creates using custom ElementDeserializer but for Content field inside use default. Unfortunately things like that:

@JsonDeserialize(using = StdDeserializer.class)
@JsonProperty
Content content;

isn't work =(

Here is my code now:

@JsonIgnoreProperties(ignoreUnknown = true)
public class Content {

    @JsonProperty("elements")
    ArrayList<Element> mElements;

}

@JsonDeserialize(using = ElementDeserializer.class)
@JsonIgnoreProperties(ignoreUnknown = true)
public class Element<T extends ElementType> {

    @JsonProperty
    Content content;

    T mField;

    public Element(T field) {
        mField = field;
    }

}

public class ElementDeserializer extends JsonDeserializer<Element> {

    @Override
    public Element deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
        Element element = null;
        JsonNode node = jp.getCodec().readTree(jp);
        if ("simple".equals(node.get("type").textValue())) {
            element = new Element(new SimpleField());
        } else if ("complex".equals(node.get("type").textValue())) {
            element = new Element(new ComplexField());
        }
        return element;
    }
}

I will be grateful for some help!

Upvotes: 2

Views: 1126

Answers (1)

Ceredig
Ceredig

Reputation: 131

Not sure whether it is mandatory for you to use a custom deserializer (for reasons not indicated in your post). If it is not, then you can do without one, using the default deserializers.

Here is how:

@JsonIgnoreProperties(ignoreUnknown = true)
public class TopObject {
    @JsonProperty
    public Content content;

    public TopObject() {
    }
}

@JsonIgnoreProperties(ignoreUnknown = true)
public class Content {

    @JsonProperty
    public Element elements [];

    public Content() {
    }
}

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type")
@JsonSubTypes({ 
    @Type(value = SimpleElement.class, name = "simple"),
    @Type(value = ComplexElement.class, name = "complex")
})
public class Element {     
    public Element() {
    }
}

public class SimpleElement extends Element {
    public SimpleElement() {
    }
}

public class ComplexElement extends Element {    
    @JsonProperty
    public Content content;

    public ComplexElement() {
    }
}

Then unserialize the json data as a TopObject.class

Upvotes: 1

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