POJO to org.bson.Document and Vice Versa

Question

Is there a simple way to convert Simple POJO to org.bson.Document?

I'm aware that there are ways to do this like this one:

Document doc = new Document();
doc.append("name", person.getName()):

But does it have a much simpler and typo less way?

Answer 1

Currently Mongo Java Driver 3.9.1 provide POJO support out of the box
http://mongodb.github.io/mongo-java-driver/3.9/driver/getting-started/quick-start-pojo/
Let's say you have such example collection with one nested object

db.createCollection("product", {
validator: {
    $jsonSchema: {
        bsonType: "object",
        required: ["name", "description", "thumb"],
        properties: {
            name: {
                bsonType: "string",
                description: "product - name - string"
            },
            description: {
                bsonType: "string",
                description: "product - description - string"
            },
            thumb: {
                bsonType: "object",
                required: ["width", "height", "url"],
                properties: {
                    width: {
                        bsonType: "int",
                        description: "product - thumb - width"
                    },
                    height: {
                        bsonType: "int",
                        description: "product - thumb - height"
                    },
                    url: {
                        bsonType: "string",
                        description: "product - thumb - url"
                    }
                }
            }

        }
    }
}});

1. Provide a MongoDatabase bean with proper CodecRegistry

@Bean
public MongoClient mongoClient() {
    ConnectionString connectionString = new ConnectionString("mongodb://username:[email protected]:27017/dbname");

    ConnectionPoolSettings connectionPoolSettings = ConnectionPoolSettings.builder()
            .minSize(2)
            .maxSize(20)
            .maxWaitQueueSize(100)
            .maxConnectionIdleTime(60, TimeUnit.SECONDS)
            .maxConnectionLifeTime(300, TimeUnit.SECONDS)
            .build();

    SocketSettings socketSettings = SocketSettings.builder()
            .connectTimeout(5, TimeUnit.SECONDS)
            .readTimeout(5, TimeUnit.SECONDS)
            .build();

    MongoClientSettings clientSettings = MongoClientSettings.builder()
            .applyConnectionString(connectionString)
            .applyToConnectionPoolSettings(builder -> builder.applySettings(connectionPoolSettings))
            .applyToSocketSettings(builder -> builder.applySettings(socketSettings))
            .build();

    return MongoClients.create(clientSettings);
}

@Bean 
public MongoDatabase mongoDatabase(MongoClient mongoClient) {
    CodecRegistry defaultCodecRegistry = MongoClientSettings.getDefaultCodecRegistry();
    CodecRegistry fromProvider = CodecRegistries.fromProviders(PojoCodecProvider.builder().automatic(true).build());
    CodecRegistry pojoCodecRegistry = CodecRegistries.fromRegistries(defaultCodecRegistry, fromProvider);
    return mongoClient.getDatabase("dbname").withCodecRegistry(pojoCodecRegistry);
}

2. Annotate your POJOS

public class ProductEntity {

    @BsonProperty("name") public final String name;
    @BsonProperty("description") public final String description;
    @BsonProperty("thumb") public final ThumbEntity thumbEntity;

    @BsonCreator
    public ProductEntity(
            @BsonProperty("name") String name,
            @BsonProperty("description") String description,
            @BsonProperty("thumb") ThumbEntity thumbEntity) {
        this.name = name;
        this.description = description;
        this.thumbEntity = thumbEntity;
    }
}

public class ThumbEntity {

    @BsonProperty("width") public final Integer width;
    @BsonProperty("height") public final Integer height;
    @BsonProperty("url") public final String url;

    @BsonCreator
    public ThumbEntity(
            @BsonProperty("width") Integer width,
            @BsonProperty("height") Integer height,
            @BsonProperty("url") String url) {
        this.width = width;
        this.height = height;
        this.url = url;
    }
}

3. Query mongoDB and obtain POJOS

MongoCollection<Document> collection = mongoDatabase.getCollection("product");
Document query = new Document();
List<ProductEntity> products = collection.find(query, ProductEntity.class).into(new ArrayList<>());

And that's it !!! You can easily obtain your POJOS without cumbersome manual mappings and without loosing ability to run native mongo queries