Specify which java type to decode an embedded document to - mongodb

Question

I have a simple java type
public class Type1_ {
private int number1;
private int number2;
public Type1_(int number1, int number2) {
this.number1 = number1;
this.number2 = number2;
}
public int getNumber1() {
return number1;
}
public int getNumber2() {
return number2;
}
#Override
public String toString() {
return "Type1_{number1=" + number1 + ", number2=" + number2 + '}';
}
public static Type1_ random() {
return new Type1_(new SecureRandom().nextInt(), new SecureRandom().nextInt());
}
}
Created a simple Codec<Type1_> for this type (with loggers to know when or if they are being used)
public class Type1_Codec implements Codec<Type1_> {
#Override
public Type1_ decode(BsonReader reader, DecoderContext decoderContext) {
reader.readStartDocument();
final int number1 = reader.readInt32("number1");
final int number2 = reader.readInt32("number2");
reader.readEndDocument();
final Type1_ type1_ = new Type1_(number1, number2);
APP_LOGGER.debug(type1_);
return type1_;
}
#Override
public void encode(BsonWriter writer, Type1_ value, EncoderContext encoderContext) {
writer.writeStartDocument();
writer.writeInt32("number1", value.getNumber1());
writer.writeInt32("number2", value.getNumber2());
writer.writeEndDocument();
APP_LOGGER.debug(value);
}
#Override
public Class<Type1_> getEncoderClass() {
return Type1_.class;
}
}
Added the codec to a registry to be used in MongoClient
public class CustomCodecRegistriesFactory {
public static CodecRegistry getDefault() {
return MongoClientSettings.getDefaultCodecRegistry();
}
public static CodecRegistry getDefaultWithType1_() {
return CodecRegistries.fromRegistries(CodecRegistries.fromCodecs(new Type1_Codec()), getDefault());
}
}
public class MongoDBClientConfig {
public static MongoClient buildMongoClientWithCustomCodec(final CodecRegistry codecRegistry) {
return MongoClients.create(MongoClientSettings.builder()
.applyToClusterSettings(builder -> {
builder.hosts(Arrays.asList(new ServerAddress(url(), port())));
})
.codecRegistry(codecRegistry)
.build());
}
}
Created a test that uses a codec registry where the Type1_Codec is included and attempt to insert (encode) and read (decode) Type1_
#TestInstance(TestInstance.Lifecycle.PER_CLASS)
public class Codecs {
#Test
public void demonstrate_simpleCustomCodec() {
final MongoClient mongoClient = buildMongoClientWithCustomCodec(CustomCodecRegistriesFactory.getDefaultWithType1_());
final MongoDatabase db = mongoClient.getDatabase("db_" + new SecureRandom().nextInt(Integer.MAX_VALUE));
final String collectionName = "col1";
db.createCollection(collectionName);
final MongoCollection<Document> col1 = db.getCollection(collectionName);
int idCounter = 0;
final String type1_field = "type1_";
printTitle("Inserting Documents");
for (int i = 0; i < 10; i++) {
/*Encoding is done at insertion*/
col1.insertOne(new Document(ID, idCounter++).append(type1_field, Type1_.random()));
}
printDocumentMongoCollection(col1);
printMongoCollectionJackson(col1);
printTitle("Attempting Decoding");
/*attempt decoding*/
// final Type1_ type1_value = col1.find().first().get(type1_field, Type1_.class);
// System.out.println(type1_value);
}
}
The problem is in the decoding part.
How do i specify for MongoClient that i want a specific document to be decoded into Type1_ type?
The commented out code will attempt to cast a Document to Type1_ and will fail.

Answer 1

use db.getCollection(collectionName, Type1_.class) to "type" your collection. That should pull your codec in to play automatically for you.