Here is a quick reference guide to MongoDB Java Driver version 3.0

How to connect to a local Database and get an handle to DB named "mydb"

MongoClient mongoClient = new MongoClient();
MongoDatabase database = mongoClient.getDatabase("mydb");

How to get an handle to the Collection named "test"

MongoCollection<Document> collection = database.getCollection("test");

How to create a Document and insert it:

Document doc = new Document("name", "MongoDB")
			   .append("type", "database")
			   .append("count", 1)
			   .append("info", new Document("x", 203).append("y", 102));

collection.insertOne(doc);

How to convert a Document into JSON:

String json = myDoc.toJson();

How to find the first Document in a Collection

Document myDoc = collection.find().first();

How to insert multiple Documents in one shot:

List<Document> documents = new ArrayList<Document>();
for (int i = 0; i < 100; i++) {
	documents.add(new Document("i", i));
}
collection.insertMany(documents);

How to count the number of Documents in a Collection:

System.out.println("total # of documents " + collection.count());

How to iterate over a Collection

MongoCursor<Document> cursor = collection.find().iterator();
try {
	while (cursor.hasNext()) {
		System.out.println(cursor.next().toJson());
	}
} finally {
	cursor.close();
}

How to find one Document whose key matches with a value:

Document myDoc = collection.find(eq("i", 71)).first();

How to find all Documents which are matching a constraint:

MongoCursor<Document> cursor = collection.find(gt("i", 50)).iterator();

How to find all Documents which are matching multiple constraints:

MongoCursor<Document> cursor = collection.find(and(gt("i", 50), lte("i", 100))).iterator();

How to apply a filter which executes a Callback method defined in a Block class:

Block<Document> printBlock = new Block<Document>() {
	@Override
	public void apply(final Document document) {
		System.out.println(document.toJson());
	}
};
collection.find(gt("i", 50)).forEach(printBlock);

How to use a Projection:

Document myDoc = collection.find().projection(excludeId()).first();

How to update a Document:

collection.updateOne(eq("i", 10), new Document("$set", new Document("i", 110)));

How to update multiple Documents:

UpdateResult updateResult = collection.updateMany(lt("i", 100),
		new Document("$inc", new Document("i", 100)));
System.out.println(updateResult.getModifiedCount());

How to delete a Document

collection.deleteOne(eq("i", 110));

How to delete multiple Documents:

DeleteResult deleteResult = collection.deleteMany(gte("i", 100));
System.out.println(deleteResult.getDeletedCount());

How to perform a Bulk write:

List<WriteModel<Document>> writes = new ArrayList<WriteModel<Document>>();
writes.add(new InsertOneModel<Document>(new Document("_id", 4)));
writes.add(new InsertOneModel<Document>(new Document("_id", 5)));
writes.add(new InsertOneModel<Document>(new Document("_id", 6)));
writes.add(new UpdateOneModel<Document>(new Document("_id", 1), new Document("$set", new Document("x", 2))));
writes.add(new DeleteOneModel<Document>(new Document("_id", 2)));
writes.add(new ReplaceOneModel<Document>(new Document("_id", 3), new Document("_id", 3).append("x", 4)));

collection.bulkWrite(writes);

 

 

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