CODEWITHSUNDEEP
javahibernatedatabase-designpersistenceclone
Agustinus Verdy
Agustinus Verdy

Reputation: 7295

Deep clone of Hibernate entity

I am wondering how can I create a deep copy of a persisted object with all of its association. Let say I have the following model.

class Document {
    String title;
    String content;
    Person owner;
    Set<Citation> citations;
}

class Person {
    String name;
    Set<Document> documents;
}

class Citation {
    String title;
    Date date;
    Set<Document> documents;
}

I have a scenario in which a user might want to grab a copy of a particular document from a person and make the document his/hers then later he / she can change its content and name. In that case I can think of one way to implement that kind of scenario which is creating a deep copy of that document (with its associations).

Or maybe if anyone knows of any other possible way to do such thing without doing huge copy of data because I know it may be bad for the app performance.

I was also thinking of may be creating a reference of to the original document like having an attribute originalDocument but that way I won't be able to know which attribute (or maybe association) has been changed.

Upvotes: 15

Views: 14788

Answers (2)

Mr_Thorynque
Mr_Thorynque

Reputation: 2002

Jackon serialisation configuration for hibernate :

  ObjectMapper mapperInstance 
     Hibernate4Module module = new Hibernate4Module();
        module.configure(Hibernate4Module.Feature.FORCE_LAZY_LOADING, false);

        mapperInstance.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
        mapperInstance.disable(MapperFeature.USE_GETTERS_AS_SETTERS);
        mapperInstance.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        mapperInstance.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);

        mapperInstance.registerModule(module);

And next 

clone = getMapperInstance().readValue(getMapperInstance().writeValueAsString(this));

Ok it cost some memory and cpu...

Upvotes: 0

Jayaram
Jayaram

Reputation: 1725

To perform a deep copy :

public static <T> T clone(Class<T> clazz, T dtls) { 
        T clonedObject = (T) SerializationHelper.clone((Serializable) dtls); 
        return clonedObject; 
  }

This utility method will give a deep copy of the entity, and you can perform your desired things what you want to do with the cloned object.

Upvotes: 7

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