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    <p>I use a way to handle it. Not sure it's perfect but it works for myself.</p> <p>Let's say you have these classes</p> <pre><code>public class MyObject { @Id private String id; private MyEmbeddedObject embeddedObject; public String getId() { return this.id; } public void setId(String id) { this.id = id; } public MyEmbeddedObject getEmbeddedObject() { return this.embeddedObject; } public void setEmbeddedObject(MyEmbeddedObject embeddedObject) { this.embeddedObject = embeddedObject; } } public class MyEmbeddedObject { @Id private String id; public String getId() { return this.id; } public void setId(String id) { this.id = id; } } </code></pre> <p>You want to store MyEmbeddedObject in collection "embed" and Object in collection "object" with a manual reference to "embed" collection ids. For example :</p> <pre><code>object : { id:1, embeddedObjectId: 99 } embed : { id : 99 } </code></pre> <p>You can implement a custom serializer and deserializer for the MyEmbeddedObject</p> <pre><code>public class MyEmbeddedObjectSerializer extends JsonSerializer&lt;MyEmbeddedObject&gt; { @Override public void serialize(MyEmbeddedObject value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException { jgen.writeText(value.getId()); } } public class MyEmbeddedObjectDeserializer extends JsonDeserializer&lt;MyEmbeddedObject&gt; { @Override public MyEmbeddedObject deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException { MyEmbeddedObject obj = new MyEmbeddedObject(); obj.setId(jsonParser.getString()); return new MyEmbeddedObject(); } } </code></pre> <p>If your register your serializer in Jongo, the problem is that it will be used for MyEmbeddedObject as a member of MyObject but also for MyEmbeddedObject when it is stored by itself in the "embed" collection.</p> <p>To apply the custom serizalizers/deserializers only when MyEmbeddedObject is embed in MyOBject, I use Mixin annotations.</p> <pre><code>public interface MyObjectMixIn { @JsonSerialize(using=MyEmbeddedObjectSerializer .class) public MyEmbeddedObject getEmbeddedObject(); @JsonDeserialize(using=MyEmbeddedObjectDeserializer.class) public void setEmbeddedObject(MyEmbeddedObject embeddedObject); } </code></pre> <p>Then define a module</p> <pre><code>public class MyModule extends SimpleModule { @Override public void setupModule(SetupContext context) { context.setMixInAnnotations(MyObject.class, MyObjectMixIn.class); } } </code></pre> <p>Finaly register the module in Jongo</p> <pre><code>Jongo jongo = new Jongo(db, JacksonMapper.Builder().registerModule(new MyModule ()).build()); </code></pre> <p>Now to use it for storage in Mongo</p> <ol> <li>Store the embeddedObject by itself in collection "embed" to get an id</li> <li>Be sure the embeddedObject member of object contains the id</li> <li>Store the object in collection "object". Only the id of the embedded object will be stored</li> </ol> <p>And to read datastore</p> <ol> <li>Read the object from collection "object". The embeddedobject will be initialize only with its ID</li> <li>If you need it, read the embeddedObject in collection "embed".</li> </ol> <p>EDIT : to avoid lazy loading and load the complete object at deserialization, <a href="http://wiki.fasterxml.com/HandlerInstantiator" rel="nofollow">HandlerInstantiator</a> object from Jackson is useful to customize serializer and deserializer construction mechanism. </p> <p>Hope that helps.</p>
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