JSOGDeserializeTest

package com.jackson.jsog;

import java.io.IOException;

import org.testng.annotations.Test;

import com.fasterxml.jackson.annotation.JsonIdentityInfo;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.ObjectIdGenerator;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JSOGDeserializeTest {

  /** the key of the property that holds the ref */
  public static final String REF_KEY = "@ref";
  
  /**
   * JSON input
   */
  private static final String EXP_EXAMPLE_JSOG = "{\"@id\":\"1\",\"foo\":66,\"next\":{\"@ref\":\"1\"}}";

  ObjectMapper mapper = new ObjectMapper();

  /**
   * Customer IdGenerator
   */
  static class JSOGGenerator extends ObjectIdGenerator<JSOGRef>  {

    private static final long serialVersionUID = 1L;
    protected transient int _nextValue;
    protected final Class<?> _scope;

    protected JSOGGenerator() { this(null, -1); }

    protected JSOGGenerator(Class<?> scope, int nextValue) {
        _scope = scope;
        _nextValue = nextValue;
    }

    @Override
    public Class<?> getScope() {
        return _scope;
    }

    @Override
    public boolean canUseFor(ObjectIdGenerator<?> gen) {
        return (gen.getClass() == getClass()) && (gen.getScope() == _scope);
    }

    @Override
    public ObjectIdGenerator<JSOGRef> forScope(Class<?> scope) {
          return (_scope == scope) ? this : new JSOGGenerator(scope, _nextValue);
    }

    @Override
    public ObjectIdGenerator<JSOGRef> newForSerialization(Object context) {
          return new JSOGGenerator(_scope, 1);
    }

    @Override
    public com.fasterxml.jackson.annotation.ObjectIdGenerator.IdKey key(Object key) {
          return new IdKey(getClass(), _scope, key);
    }

    @Override
    public JSOGRef generateId(Object forPojo) {
          int id = _nextValue;
          ++_nextValue;
          return new JSOGRef(id);
    }

  }


  /**
   * The reference deserializer
   */
  static class JSOGRefDeserializer extends JsonDeserializer<JSOGRef>
  {
    @Override
    public JSOGRef deserialize(JsonParser jp, DeserializationContext ctx) throws IOException, JsonProcessingException {
      JsonNode node = jp.readValueAsTree();
      if (node.isTextual()) {
        return new JSOGRef(node.asInt());
      } else {
        return new JSOGRef(node.get(REF_KEY).asInt());
      }
    }
  
  }

  /**
   * The reference object
   */
  @JsonDeserialize(using=JSOGRefDeserializer.class)
  static class JSOGRef
  {

    @JsonProperty(REF_KEY)
    public int ref;

    public JSOGRef() {
    }

    public JSOGRef(int val) {
      ref = val;
    }
  }

  
  /**
   * Example class using JSOGGenerator
   */
  @JsonIdentityInfo(generator=JSOGGenerator.class)
  public static class IdentifiableExampleJSOG {
    public int foo;
    public IdentifiableExampleJSOG next;
  }




  @Test
  public void testStructJSOGRef() throws Exception {
    
    // Because the value ({@ref:1}) is not scalar, parser thinks it is not an id 
    // and tries to deserialize as normal a new IdentifiableExampleJSOG 
    // then  complains about unrecognized field "@ref"
    IdentifiableExampleJSOG result = mapper.readValue(EXP_EXAMPLE_JSOG, IdentifiableExampleJSOG.class);
    
    assert 66 == result.foo;
    assert result == result.next;
  }
}