推土机深度映射字段为String

Question

I have an object that is entirely too complicated.

public class OrderItem {
    private Survey survey;
    ...
}

public class Survey {
    private QuestionAnswerGroup questionAnswerGroup;
    ...
}

public class QuestionAnswerGroup {
    private Map<String, List<QuestionAnswerSet>> questionAnswerSets;
    ...
}

My goal is to flatten the questionAnswerSets map so that all of the lists in the values are consolidated into one as

public class OrderItemDTO {
    private List<OrderItemQuestionAnswer> survey;
    ...
}

Rather than try to figure out how to join all those lists into one in Dozer, which I'm not sure it can even do, I wrote a custom setter.

<mapping wildcard="false">
    <class-a>OrderItem</class-a>
    <class-b>OrderItemDTO</class-b>
    <field>
        <a get-method="getSurvey" is-accessible="false">survey</a>
        <b set-method="makeFlatSurvey" get-method="makeDomainSurvey" is-accessible="false">survey</b>
    </field>
    ...
</mapping>

Which I would assume would mean that Dozer would simply read the Survey off of the first object and plop it into makeFlatSurvey but instead it is reading off the questionAnswerGroup field on the Survey object and then going through each item in the questionAnswerSets and replacing them with a String version of themselves. A breakpoint in the toString method on QuestionAnswerSet shows that Dozer is calling that as part of its process.

I'm stumped here on a way to force Dozer to just accept the Survey object without changing it.

Answer 1

The only way I've found to do this is to set copy-by-reference to true.

You haven't posted OrderItemQuestionAnswer class, but I'm assuming it's as follows:

public class OrderItemQuestionAnswer {
    private String question;
    private String answer;  
    // Getters/setters and toString omitted
}

I'm also assuming OrderItemDTO.makeFlatSurvey looks something like this:

public void makeFlatSurvey(Survey survey)
{
    for (List<QuestionAnswerSet> questionAnswerSets : survey.getQuestionAnswerGroup().getQuestionAnswerSets().values())
    {
        for (QuestionAnswerSet questionAnswerSet : questionAnswerSets)
        {
            OrderItemQuestionAnswer orderItemQuestionAnswer = new OrderItemQuestionAnswer();
            orderItemQuestionAnswer.setQuestion(questionAnswerSet.getQuestion());
            orderItemQuestionAnswer.setAnswer(questionAnswerSet.getAnswer());
            this.survey.add(orderItemQuestionAnswer);
        }
    }
}

Modifying the field element in the mapping and adding copy-by-reference="true" will prevent the ClassCastException (I have no idea why):

<mapping wildcard="false">
    <class-a>OrderItem</class-a>
    <class-b>OrderItemDTO</class-b>
    <field copy-by-reference="true">
        <a get-method="getSurvey" is-accessible="false">survey</a>
        <b set-method="makeFlatSurvey" get-method="makeDomainSurvey" is-accessible="false">survey</b>
    </field>
    ...
</mapping>