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POUnable to deserializ​e a Set of polymorphi​c objects (Jackson 2.1.2)
 

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  1. POUnable to deserializ​e a Set of polymorphi​c objects (Jackson 2.1.2)
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    <p>I’m trying to deserialize the following:</p> <pre><code>{ "type":"GIQuestionnaire", "id":6051, "questions":[ { "type":"IncludeExcludeQuestion", "id":24057, "answers":[ { "type":"IncludeExcludeAnswer", "id":101497 }, { "type":"IncludeExcludeAnswer", "id":101496 } ] } ] } </code></pre> <p>Which results in this error:</p> <pre><code>java.lang.AssertionError: Can not handle managed/back reference 'questionnaire-questions': value deserializer is of type ContainerDeserializerBase, but content type is not handled by a BeanDeserializer (instead it's of type com.foo.questionnaire.json.QuestionDeserializer) </code></pre> <p>The Junit test:</p> <pre><code>@Test public void testDeserializeQuestionnaire() { ObjectMapper mapper = new ObjectMapper(); GIQuestionnaire q = manager.createGIQuestionnaire(…); try { String json = mapper.writeValueAsString(q); assertTrue(q.equals(mapper.readValue(json, GIQuestionnaire.class))); } catch (Exception e) { fail(e.getMessage()); } } </code></pre> <p>A Questionnaire contains a Set (implemented as TreeSet) of Question objects. A Question contains a Set (TreeSet) of Answer objects.</p> <p>Here are the relevant snippets of code that show how I used Jackson annotations:</p> <pre><code>// Questionnaire abstract base class @JsonTypeInfo(use=JsonTypeInfo.Id.NAME, include=JsonTypeInfo.As.PROPERTY, property="type") @JsonSubTypes({ @JsonSubTypes.Type(value=GIQuestionnaire.class, name="GIQuestionnaire"), @JsonSubTypes.Type(value=PolicyQuestionnaire.class, name="PolicyQuestionnaire") }) public abstract class Questionnaire implements Serializable { @JsonManagedReference("questionnaire-questions") @JsonDeserialize(as = TreeSet.class, contentAs = Question.class) private Set&lt;Question&gt; questions = new TreeSet&lt;&gt;(); // … remainder omitted for brevity } // Question abstract base class @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type") @JsonSubTypes({ @JsonSubTypes.Type(value = EntityQuestion.class, name = "EntityQuestion"), @JsonSubTypes.Type(value = IncludeExcludeQuestion.class, name = "IncludeExcludeQuestion") }) @JsonDeserialize(using = QuestionDeserializer.class) public abstract class Question implements Comparable&lt;Question&gt;, Serializable { @JsonBackReference("questionnaire-questions") private Questionnaire questionnaire; @JsonManagedReference("question-answers") @JsonDeserialize(as = TreeSet.class, contentAs = Answer.class) private Set&lt;Answer&gt; answers = new TreeSet&lt;&gt;(); // … remainder omitted for brevity } // Answer abstract base class @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type") @JsonSubTypes({ @JsonSubTypes.Type(value = EntityAnswer.class, name = "EntityAnswer"), @JsonSubTypes.Type(value = IncludeExcludeAnswer.class, name = "IncludeExcludeAnswer") }) @JsonDeserialize(using = AnswerDeserializer.class) public abstract class Answer implements Comparable&lt;Answer&gt;, Serializable { @JsonBackReference("question-answers") private Question question; // … remainder omitted for brevity } public class QuestionDeserializer extends JsonDeserializer&lt;Question&gt; { @Override public Question deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException { //deserialize a Question to a concrete instance } } public class AnswerDeserializer extends JsonDeserializer&lt;Answer&gt; { @Override public Answer deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException { //deserialize an Answer to a concrete instance } } </code></pre> <p>Where am I going wrong with my annotations and/or Deserializers? Thanks very much!</p>
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