I'm using Jackson 2.8.0 to serialize some JPA Entities over a REST API with
Spring Data REST. I'm having a problem with serializing an Array of
Entities that contain references to the same child object. All objects are
using JsonIdentityInfo as below, where the key property is a Long @Id field.
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
property = "key", scope = MyClass.class)
I believe the expected JSON should look like the below. The relevant object
is supportEmailAddress.
"companies" : [ {
"key" : 1,
"name" : "company1",
*"supportEmailAddress" : { "key" : 1, "emailAddrType" : "support",
"emailAddress" : "[email protected]" }*
"aliases" : [ ],
"contacts" : [ ],
"owner" : {
"key" : 1,
"name" : "owner 1",
"contacts" : [ ],
"_links" : {
"company" : {
"href" : "http://localhost:8080/company/1";
}
}
}
}, {
"key" : 2,
"name" : "company2",
*"supportEmailAddress" : {[1]}*
"aliases" : [ ],
"contacts" : [ ],
"owner" : {
"key" : 2,
"name" : "owner 2",
"contacts" : [ ],
"_links" : {
"company" : {
"href" : "http://localhost:8080/company/2";
}
}
}
The first time the child object is referenced, it serializes correctly. The
second time, it fails with the stack trace below.
<...>
Caused by: com.fasterxml.jackson.core.JsonGenerationException: Can not
write a number, expecting field name
at
com.fasterxml.jackson.core.JsonGenerator._reportError(JsonGenerator.java:1676)
at
com.fasterxml.jackson.core.json.UTF8JsonGenerator._verifyValueWrite(UTF8JsonGenerator.java:925)
at
com.fasterxml.jackson.core.json.UTF8JsonGenerator.writeNumber(UTF8JsonGenerator.java:787)
at
com.fasterxml.jackson.databind.ser.std.NumberSerializers$LongSerializer.serialize(NumberSerializers.java:188)
at
com.fasterxml.jackson.databind.ser.impl.WritableObjectId.writeAsId(WritableObjectId.java:35)
at
com.fasterxml.jackson.databind.ser.std.BeanSerializerBase._serializeWithObjectId(BeanSerializerBase.java:584)
at
com.fasterxml.jackson.databind.ser.impl.UnwrappingBeanSerializer.serialize(UnwrappingBeanSerializer.java:114)
at
com.fasterxml.jackson.databind.ser.impl.UnwrappingBeanPropertyWriter.serializeAsField(UnwrappingBeanPropertyWriter.java:127)
at
com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:678)
at
com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:157)
at
com.fasterxml.jackson.databind.SerializerProvider.defaultSerializeValue(SerializerProvider.java:985)
at
org.springframework.data.rest.webmvc.json.PersistentEntityJackson2Module$PersistentEntityResourceSerializer.serialize(PersistentEntityJackson2Module.java:193)
at
org.springframework.data.rest.webmvc.json.PersistentEntityJackson2Module$PersistentEntityResourceSerializer.serialize(PersistentEntityJackson2Module.java:140)
at
com.fasterxml.jackson.databind.SerializerProvider.defaultSerializeValue(SerializerProvider.java:985)
at
org.springframework.data.rest.webmvc.json.PersistentEntityJackson2Module$NestedEntitySerializer.serialize(PersistentEntityJackson2Module.java:356)
at
com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:672)x
at
com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:678)
at
com.fasterxml.jackson.databind.ser.std.BeanSerializerBase._serializeWithObjectId(BeanSerializerBase.java:600)
at
com.fasterxml.jackson.databind.ser.impl.UnwrappingBeanSerializer.serialize(UnwrappingBeanSerializer.java:114)
at
com.fasterxml.jackson.databind.ser.impl.UnwrappingBeanPropertyWriter.serializeAsField(UnwrappingBeanPropertyWriter.java:127)
at
com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:678)
at
com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:157)
at
com.fasterxml.jackson.databind.SerializerProvider.defaultSerializeValue(SerializerProvider.java:985)
at
org.springframework.data.rest.webmvc.json.PersistentEntityJackson2Module$PersistentEntityResourceSerializer.serialize(PersistentEntityJackson2Module.java:193)
at
org.springframework.data.rest.webmvc.json.PersistentEntityJackson2Module$PersistentEntityResourceSerializer.serialize(PersistentEntityJackson2Module.java:140)
at
com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:119)
at
com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:79)
at
com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:18)
at
com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:616)
at
com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:519)
at
com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:31)
at
org.springframework.hateoas.hal.Jackson2HalModule$HalResourcesSerializer.serialize(Jackson2HalModule.java:340)
at
org.springframework.hateoas.hal.Jackson2HalModule$HalResourcesSerializer.serialize(Jackson2HalModule.java:302)
at
com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:672)
at
com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:678)
at
com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:157)
at
com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:130)
at
com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1428)
at
com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:930)
at
org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:269)
... 57 more
If I remove the JsonIdentityInfo, I get the results back correctly.
However, there are no Object references, and the full child object is
serialized every time it is referenced. I'm concerned that this "fix" is
not effective, because I originally added the JsonIdentityInfo annotations
to get around some recursive relationships (ORM bi-directional stuff). If I
have to remove them every time I might refer to the same instance in a
result set, what is the point of the JsonIdentityInfo annotation in the
first place?
I'm sure I'm just applying something incorrectly, but I'm not able to find
documentation on what I may be missing. Do I need a custom serializer to
make use of this feature?
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