Use Mongo Scala Driver Macros to read documents with additional nested fields

Question

Is it possible to use the mongo-scala-driver macros to read documents from a mongo db which contain additional fields to the fields specified in the case classes?

I expected the fields not specified in the case classes but in the document to be ignored on deserialisation. But an exception is thrown. Due to the schema less approach of mongo db it is impossible to specify the total set of fields in the case classes.

The Document I want to deserialize looks like this json:

{
    "_id": 6,
    "nestedOne": {
        "nestedOneOne": 123,
        "nestedOneTwo": 456
    },
    "nestedTwo": {
        "nestedTwoOne": 789
    }
}

I expected the following minimal example to work:

import org.bson.codecs.configuration.CodecRegistries.{fromProviders, fromRegistries}
import org.bson.codecs.configuration.CodecRegistry
import org.mongodb.scala.bson.codecs.DEFAULT_CODEC_REGISTRY
import org.mongodb.scala.bson.codecs.Macros._
import org.mongodb.scala.model.Filters
import org.mongodb.scala.MongoClient
import org.mongodb.scala.bson.collection.immutable.Document
import scala.concurrent.Await

import scala.concurrent.duration._

// prepare the case classes and register them
case class TestDocument(_id: Int, nestedOne: Option[NestedOne])
case class NestedOne(nestedOneOne: Int, nestedOneTwo: Int)
val testCodecRegistry: CodecRegistry = fromRegistries(
  fromProviders(classOf[TestDocument], classOf[NestedOne]),
  DEFAULT_CODEC_REGISTRY
)

// prepare the test data & insert them
val testDocument = Document(
  "_id" -> 6,
  "nestedOne" -> Document("nestedOneOne" -> 123, "nestedOneTwo" -> 456),
  "nestedTwo" -> Document("nestedTwoOne" -> 789)
)

val mongoClient = MongoClient("mongodb://localhost:1234")
val database = mongoClient.getDatabase("testdatabase")
val testCollection = database.getCollection("test_collection").withCodecRegistry(testCodecRegistry)
Await.result(testCollection.insertOne(testDocument).toFuture, 2.minutes)

// try to read and deserialize the document again
val _ = Await.result(testCollection.find[TestDocument](Filters.equal("_id", 6)).toFuture(), 2.minutes)

But the following Exception is thrown:

head of empty list
java.util.NoSuchElementException: head of empty list
    at scala.collection.immutable.Nil$.head(List.scala:428)
    at scala.collection.immutable.Nil$.head(List.scala:425)
    at org.mongodb.scala.bson.codecs.macrocodecs.MacroCodec.readDocument(MacroCodec.scala:204)
    at org.mongodb.scala.bson.codecs.macrocodecs.MacroCodec.readDocument$(MacroCodec.scala:193)
    at de.peterschrott.mongotest.MongoTest$$anon$1$TestDocumentMacroCodec$3.readDocument(MongoTest.scala:29)
    at org.mongodb.scala.bson.codecs.macrocodecs.MacroCodec.readValue(MacroCodec.scala:173)
    at org.mongodb.scala.bson.codecs.macrocodecs.MacroCodec.readValue$(MacroCodec.scala:169)
    at de.peterschrott.mongotest.MongoTest$$anon$1$TestDocumentMacroCodec$3.readValue(MongoTest.scala:29)
    at org.mongodb.scala.bson.codecs.macrocodecs.MacroCodec.decode(MacroCodec.scala:104)
    at org.mongodb.scala.bson.codecs.macrocodecs.MacroCodec.decode$(MacroCodec.scala:96)
    at de.peterschrott.mongotest.MongoTest$$anon$1$TestDocumentMacroCodec$3.decode(MongoTest.scala:29)
    at com.mongodb.operation.CommandResultArrayCodec.decode(CommandResultArrayCodec.java:52)
    at com.mongodb.operation.CommandResultDocumentCodec.readValue(CommandResultDocumentCodec.java:53)
    at org.bson.codecs.BsonDocumentCodec.decode(BsonDocumentCodec.java:84)
    at org.bson.codecs.BsonDocumentCodec.decode(BsonDocumentCodec.java:41)
    at org.bson.codecs.configuration.LazyCodec.decode(LazyCodec.java:47)
    at org.bson.codecs.BsonDocumentCodec.readValue(BsonDocumentCodec.java:101)
    at com.mongodb.operation.CommandResultDocumentCodec.readValue(CommandResultDocumentCodec.java:56)
    at org.bson.codecs.BsonDocumentCodec.decode(BsonDocumentCodec.java:84)
    at org.bson.codecs.BsonDocumentCodec.decode(BsonDocumentCodec.java:41)
    at com.mongodb.connection.ReplyMessage.(ReplyMessage.java:57)
    at com.mongodb.connection.CommandProtocol.getResponseDocument(CommandProtocol.java:139)
    at com.mongodb.connection.CommandProtocol.access$000(CommandProtocol.java:51)
    at com.mongodb.connection.CommandProtocol$CommandResultCallback.callCallback(CommandProtocol.java:271)
    at com.mongodb.connection.ResponseCallback.onResult(ResponseCallback.java:48)
    at com.mongodb.connection.ResponseCallback.onResult(ResponseCallback.java:23)
    at com.mongodb.connection.DefaultConnectionPool$PooledConnection$2.onResult(DefaultConnectionPool.java:470)
    at com.mongodb.connection.DefaultConnectionPool$PooledConnection$2.onResult(DefaultConnectionPool.java:464)
    at com.mongodb.connection.UsageTrackingInternalConnection$3.onResult(UsageTrackingInternalConnection.java:119)
    at com.mongodb.connection.UsageTrackingInternalConnection$3.onResult(UsageTrackingInternalConnection.java:115)
    at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
    at com.mongodb.connection.InternalStreamConnection.executeCallbackAndReceiveResponse(InternalStreamConnection.java:378)
    at com.mongodb.connection.InternalStreamConnection.access$1700(InternalStreamConnection.java:66)
    at com.mongodb.connection.InternalStreamConnection$ResponseBuffersCallback.onResult(InternalStreamConnection.java:420)
    at com.mongodb.connection.InternalStreamConnection$ResponseBuffersCallback.onResult(InternalStreamConnection.java:389)
    at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback.onSuccess(InternalStreamConnection.java:562)
    at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback.access$2200(InternalStreamConnection.java:517)
    at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback$ResponseBodyCallback.onResult(InternalStreamConnection.java:584)
    at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback$ResponseBodyCallback.onResult(InternalStreamConnection.java:568)
    at com.mongodb.connection.InternalStreamConnection$3.completed(InternalStreamConnection.java:447)
    at com.mongodb.connection.InternalStreamConnection$3.completed(InternalStreamConnection.java:444)
    at com.mongodb.connection.AsynchronousSocketChannelStream$BasicCompletionHandler.completed(AsynchronousSocketChannelStream.java:218)
    at com.mongodb.connection.AsynchronousSocketChannelStream$BasicCompletionHandler.completed(AsynchronousSocketChannelStream.java:201)
    at sun.nio.ch.Invoker.invokeUnchecked(Invoker.java:126)
    at sun.nio.ch.Invoker.invokeDirect(Invoker.java:157)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.implRead(UnixAsynchronousSocketChannelImpl.java:553)
    at sun.nio.ch.AsynchronousSocketChannelImpl.read(AsynchronousSocketChannelImpl.java:276)
    at sun.nio.ch.AsynchronousSocketChannelImpl.read(AsynchronousSocketChannelImpl.java:297)
    at com.mongodb.connection.AsynchronousSocketChannelStream.readAsync(AsynchronousSocketChannelStream.java:125)
    at com.mongodb.connection.InternalStreamConnection.readAsync(InternalStreamConnection.java:444)
    at com.mongodb.connection.InternalStreamConnection.access$2000(InternalStreamConnection.java:66)
    at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback.onResult(InternalStreamConnection.java:541)
    at com.mongodb.connection.InternalStreamConnection$ResponseHeaderCallback.onResult(InternalStreamConnection.java:517)
    at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
    at com.mongodb.connection.InternalStreamConnection$3.completed(InternalStreamConnection.java:447)
    at com.mongodb.connection.InternalStreamConnection$3.completed(InternalStreamConnection.java:444)
    at com.mongodb.connection.AsynchronousSocketChannelStream$BasicCompletionHandler.completed(AsynchronousSocketChannelStream.java:218)
    at com.mongodb.connection.AsynchronousSocketChannelStream$BasicCompletionHandler.completed(AsynchronousSocketChannelStream.java:201)
    at sun.nio.ch.Invoker.invokeUnchecked(Invoker.java:126)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.finishRead(UnixAsynchronousSocketChannelImpl.java:430)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.finish(UnixAsynchronousSocketChannelImpl.java:191)
    at sun.nio.ch.UnixAsynchronousSocketChannelImpl.onEvent(UnixAsynchronousSocketChannelImpl.java:213)
    at sun.nio.ch.KQueuePort$EventHandlerTask.run(KQueuePort.java:301)
    at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(AsynchronousChannelGroupImpl.java:112)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

Is there a way to tackle the addressed issue?

Use Mongo Scala Driver Macros to read documents with additional nested fields

Answers (1)

Related Questions