Deserialization of empty JsonNode fails if @JsonValue is used

[agavrilov76]

I'm not sure whether this is a defect, but I'm getting an exception when trying to de-serialize an empty "{}" object into a JsonNode when using @jsonvalue.

Please see the code below:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonValue;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;

import java.io.IOException;

/**
 * Deserialization of an empty JsonNode fails if  @JsonValue is used
 */
public class JsonNodeIssue {

    @JsonDeserialize(as = JsonDataImpl.class)
    public static interface Data {
        String getString();
    }

    public static class JsonDataImpl implements Data {
        private final JsonNode jsonNode;

        @JsonCreator
        public JsonDataImpl(JsonNode jsonNode) {
            this.jsonNode = jsonNode;
        }

        @JsonValue
        public JsonNode getJsonNode() {
            return jsonNode;
        }

        @Override
        public String getString() {
            JsonNode string = jsonNode.get("string");
            return string == null ? null : string.toString();
        }
    }

    @JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
    public static class DataImpl implements Data {

        final private String string;

        public DataImpl(String string) {
            this.string = string;
        }

        @Override
        public String getString() {
            return string;
        }
    }

    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper();

        System.out.println("Json: " + new String(mapper.writeValueAsBytes(new DataImpl("abc"))));
        System.out.println("Json2: " + new String(mapper.writeValueAsBytes(new DataImpl(null))));

        Data data = mapper.readValue("{\"string\":\"abc\"}", Data.class);
        System.out.println("string1:" + data.getString());

        // the following line fails:
        data = mapper.readValue("{}", Data.class);
        System.out.println("string2:" + data.getString());
    }
}

Here is the output:

Json: {"string":"abc"}
Json2: {}
Exception in thread "main" com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of com.fasterxml.jackson.databind.JsonNode out of END_OBJECT token
 at [Source: java.io.StringReader@2b94d9d5; line: 1, column: 2]
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:164)
    at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:575)
    at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:569)
    at com.fasterxml.jackson.databind.deser.std.BaseNodeDeserializer.deserializeAny(JsonNodeDeserializer.java:322)
    at com.fasterxml.jackson.databind.deser.std.JsonNodeDeserializer.deserialize(JsonNodeDeserializer.java:63)
    at com.fasterxml.jackson.databind.deser.std.JsonNodeDeserializer.deserialize(JsonNodeDeserializer.java:15)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:973)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:276)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2034)
    at JsonNodeIssue.main(JsonNodeIssue.java:65)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)
string1:"abc"

[cowtowncoder]

Quick question: which version is this with? 2.3.0 was just released, and I could not reproduce this immediately with a simplified test, so I want to make sure problem still exists.

[cowtowncoder]

Ah. Actually, I can reproduce it, when keeping @JsonCreator.