Correct me if I am wrong, but the approach you described works well when I
want to serialize the POJO into JSON (by using a custom serializer and
overriding serialize method). However, what I actually want to achieve is
change how POJO is used to obtain the AVRO schema from the POJO. I want to
generate an AVRO schema that is able to parse Mongo generated JSON. Now as
I said, Mongo stores ObjectId as :
'id' : {
'oid' : '24-character-hex-string';
}
So, is there any way to override some methods and get that? It's something
similar to the JSON serialization you said about, but for AVRO schema
generation.
On Thursday, October 24, 2019 at 5:19:37 AM UTC+5:30, Tatu Saloranta wrote:
>
> Ok, so: if you do want `ObjectId` type handled, you will just need to
> provide a custom serializer (JsonSerializer), registered for that type:
> otherwise it is assumed to be a Bean, and properties discovered. This is
> probably the easiest way.
>
> If you just want to ignore all properties with value of ObjectId, there
> are couple of ways to do that: `@JsonIgnoreType` annotation on class does
> it -- in this case you would want to attach it via mix-in.
> But Jackson 2.9 adds "config override" support too, something like:
>
> mapper.configOverride(ObjectId.class).setIsIgnoredType(true);
>
> I hope this helps,
>
> -+ Tatu +-
>
>
> On Wed, Oct 23, 2019 at 12:26 AM Amit Singh <amitd...@gmail.com
> <javascript:>> wrote:
>
>> I have been able to track down the solution to somehow overriding
>> expectAnyFormat in VisitorFormatWrapperImpl.java but have no clue how to
>> do that. Is there someway I can extend that?
>>
>> On Tuesday, October 22, 2019 at 8:14:18 PM UTC+5:30, Amit Singh wrote:
>>>
>>> I was trying to modify how ObjectId is serialized by the Jackson Avro
>>> library. Default serializer creates an AVRO having following structure :
>>>
>>> {
>>> "name" : "id",
>>> "type" : [ "null", {
>>> "type" : "record",
>>> "name" : "ObjectId",
>>> "namespace" : "org.bson.types",
>>> "fields" : [ {
>>> "name" : "counter",
>>> "type" : {
>>> "type" : "int",
>>> "java-class" : "java.lang.Integer"
>>> }
>>> }, {
>>> "name" : "date",
>>> "type" : [ "null", {
>>> "type" : "long",
>>> "java-class" : "java.util.Date"
>>> } ]
>>> }, {
>>> "name" : "machineIdentifier",
>>> "type" : {
>>> "type" : "int",
>>> "java-class" : "java.lang.Integer"
>>> }
>>> }, {
>>> "name" : "processIdentifier",
>>> "type" : {
>>> "type" : "int",
>>> "java-class" : "java.lang.Short"
>>> }
>>> }, {
>>> "name" : "time",
>>> "type" : {
>>> "type" : "long",
>>> "java-class" : "java.lang.Long"
>>> }
>>> }, {
>>> "name" : "timeSecond",
>>> "type" : {
>>> "type" : "int",
>>> "java-class" : "java.lang.Integer"
>>> }
>>> }, {
>>> "name" : "timestamp",
>>> "type" : {
>>> "type" : "int",
>>> "java-class" : "java.lang.Integer"
>>> }
>>> } ]
>>> } ]
>>> }
>>>
>>> However, MongoDB has following format for ObjectId as per official
>>> source
>>> <https://github.com/mongodb/specifications/blob/master/source/extended-json.rst#conversion-table>
>>>
>>> :
>>>
>>> {"$oid": <ObjectId bytes as 24-character, big-endian
>>> *hexstring*>}
>>>
>>> So ideally, the AVRO, that I want to generate for this, should have the
>>> following structure :
>>>
>>> {
>>> "name" : "oid",
>>> "type" : {
>>> "type" : "string"
>>> }
>>> }]
>>> }
>>>
>>> What I have been able to do so far is to extend the SerializerModifier
>>> and use changeProperties to remove all the fields generated by the ObjectId
>>> by first comparing the class. However, using this approach, I am not able
>>> to create my own property to add to the List<BeanPropertyWriter> which
>>> later gets serialized.
>>>
>>> public class ObjectIdSerializerModifier extends BeanSerializerModifier {
>>>
>>> @Override
>>> public List<BeanPropertyWriter> changeProperties(SerializationConfig
>>> config, BeanDescription beanDesc, List<BeanPropertyWriter> beanProperties) {
>>> if ( beanDesc.getBeanClass().equals(ObjectId.class) ) {
>>> beanProperties.clear(); // I need to add the 'oid' string
>>> element here.
>>> }
>>> return beanProperties;
>>> }
>>> }
>>>
>>>
>>> The above code piece fails with the following error :
>>>
>>> com.fasterxml.jackson.databind.exc.InvalidDefinitionException: "Any"
>>> type (usually for `java.lang.Object`) not supported: `expectAnyFormat`
>>> called with type [simple type, class org.bson.types.ObjectId]
>>> at
>>> com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:77)
>>> at
>>> com.fasterxml.jackson.dataformat.avro.schema.VisitorFormatWrapperImpl.expectAnyFormat(VisitorFormatWrapperImpl.java:174)
>>> at
>>> com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.acceptJsonFormatVisitor(UnknownSerializer.java:66)
>>> at
>>> com.fasterxml.jackson.dataformat.avro.schema.RecordVisitor.schemaFieldForWriter(RecordVisitor.java:178)
>>> at
>>> com.fasterxml.jackson.dataformat.avro.schema.RecordVisitor.optionalProperty(RecordVisitor.java:121)
>>> at
>>> com.fasterxml.jackson.databind.ser.BeanPropertyWriter.depositSchemaProperty(BeanPropertyWriter.java:839)
>>> at
>>> com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.acceptJsonFormatVisitor(BeanSerializerBase.java:863)
>>> at
>>> com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.acceptJsonFormatVisitor(DefaultSerializerProvider.java:566)
>>> at
>>> com.fasterxml.jackson.databind.ObjectMapper.acceptJsonFormatVisitor(ObjectMapper.java:4046)
>>> at
>>> com.fasterxml.jackson.databind.ObjectMapper.acceptJsonFormatVisitor(ObjectMapper.java:4025)
>>> at com.amitds1997.avroserializer.Main.main(Main.java:55)
>>>
>>> This is probably because I have emptied the List and it no longer
>>> contains any elements. So how can I do this? Also, is this the right
>>> approach to take or should I modify some other parameters and functions?
>>>
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