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POJackson/GSON: Selecting a different representation when object has been reached via a relationship
 

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    <p>I have a large object graph from which I would like to expose objects in a RESTful via a web-service. All objects feature an id-property, which serves as a primary key unique within the objects of that class. Further, all relationships in my object graph are bi-directional. When exposing an instance as a REST resource, I need all attributes of the instance to be written to JSON; however, I want the instances that are associated via relationships merely to be represented by their id, rather than having the entire object serialised to JSON.</p> <p>Example: So, say a Person has a Dog and a Dog has a Person.</p> <pre><code>class Person { private Integer id; private String firstName; private String lastName; private Dog dog; // public getters/setters omitted } class Dog { private Integer id; private String name; private Person owner; // public getters/setters omitted } </code></pre> <p>When serialising a given dog, I need the result to be:</p> <pre><code>{"id": 24, "name": "Fifo", "owner": 42} </code></pre> <p>And when serialising a given Person, I need the result to be:</p> <pre><code>{"id": 42, "firstName": "John", "lastName": "Blogs", "dog": 24} </code></pre> <p>rather than</p> <pre><code>{"id": 24, "name": "Fifo", "owner": {"id": 42, "firstName": "John", "lastName": "Blogs", "dog": 24} } </code></pre> <p>and</p> <pre><code>{"id": 42, "firstName": "John", "lastName": "Blogs", "dog": {"id": 24, "name": "Fifo", "owner": 42} } </code></pre> <p>respectively. I have played with the @JsonValue annotation in Jackson on the getId() method, but unfortunately, that applies always no matter whether the object it directly serialised or whether the object is reached via a relationship from another object.</p> <p>I would have thought, that this use case is reasonably common. If this is not possible, what do other people do when exposing objects in an object graph via a RESTful API.</p> <p>Thank you.</p>
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    1. COdid anything ever come of this post? Was a feature request put in, or did you find out a way of handling this situation? I am trying to do **exactly** the same kind of thing but I haven't found much information, other than folks saying to use @JsonIgnore or the Jackson bi-directional reference annotations (which won't work for this situation since the goal is not to completely ignore those fields when serializing). So far it's looking like using GSON and creating a custom GsonBuilder is my only option, but I've heard a lot of not-so-great opinions of GSON and I'm wondering if there
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    2. COAmanda. Sorry, no I have not worked out how to do this with Jackson. I agree, it's a rather straight forward feature and I have been wondering why not more people run into the same problem. I probably should have put in a feature request but I didn't. The JSON I needed to generate was reasonably simple, so I just did it myself and stopped using Jackson altogether. A pity really.
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