JsonMappingException: Already had POJO for id

Question

I have an error when trying to work with @JsonIdentityInfo jackson annotation. When I try to deserialize the object I get the following exception:

Could not read JSON: Already had POJO for id (java.lang.Integer) [1] (through reference chain: eu.cobiz.web.domain.Site["operators"]->eu.yavix.web.domain.Account["image"]->eu.cobiz.web.domain.Image["@Image"]);nested exception is com.fasterxml.jackson.databind.JsonMappingException: Already had POJO for id (java.lang.Integer) [1] (through reference chain: eu.yavix.web.domain.Site["operators"]->eu.cobiz.web.domain.Account["image"]->eu.cobiz.web.domain.Image["@Image"])

The JSON I am trying to deserialize looks like:

{ "@Site": 1, "siteId": 1, "name": "0", "address": {     "@Address": 2,     "addressId": 4,     "number": "22" }, "operators": [     {         "accountId": 1,         "email": "[email protected]",         "image": {             "@Image": 1,             "imageId": 1,             "uri": "http://icons.iconarchive.com/icons/deleket/purple-monsters/128/Alien-awake-icon.png"         }     },     {         "accountId": 2,         "email": "[email protected]",         "image": {             "@Image": 2,             "imageId": 2,             "uri": "http://icons.iconarchive.com/icons/deleket/purple-monsters/128/Alien-awake-icon.png"         }     } ] } 

My domain object is annotated with

@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "@Image") 

The problem arises on @Id annotation since if I remove the annotation the problem disappears (as I did for account) but on my understanding the new feature is useful for cyclic dependencies which is useful for me in other scenarios. There shouldn't be a conflict between the 2 images since they are different objects.

How can I solve this or what is the problem?

Answer 1

You should use scope parameter when annotating the ids. Then the de-serializer would make sure the id is unique within the scope.

From Annotation Type JsonIdentityInfo:

Scope is used to define applicability of an Object Id: all ids must be unique within their scope; where scope is defined as combination of this value and generator type.

e.g.

@JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class,property="@id", scope = Account.class)