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How to upgrade this code to latest Mongo Java driver?

I am working on this legacy application (7 years old). I have many methods that do the same thing that I am trying to upgrade to a newer MongoDB Java driver, but it won't compile.
#Override
public void saveOrUpdatePrinter(Document printer) {
printer.put(PRINTER_COLUMNS.updateDate,new Date());
MongoCollection<Document> collection = mongoTemplate.getCollection("PRINTERS");
printer.remove("_id");
Document query = new Document().append(PRINTER_COLUMNS.internal_id, printer.get(PRINTER_COLUMNS.internal_id));
WriteResult result = collection.update(query, printer, true, false);
logger.debug("saveOrUpdatePrinter updeded records: " + result.getN());
}//
The error is:
The method update(Document, Document, boolean, boolean) is undefined
for the type MongoCollection<Document>
Why was this removed?
printer.remove("_id");
Also I would like to know how to do either update or save on the document in one go?
And what will be the proper way to update a single document in the new (MongoDB Java driver 4.7.0)?
Reading this code a little more seems like it was an attempt to do UPSERT operation (update or insert).

I will try to answer your questions.
Q : How to do either Update or Save on the Document in one go?
-> MongoDB's update method updates the values in the existing document whereas the save method replaces the existing document with the document passed. Nothing happens in one go.
update method only updates which are specific fields which are modified by comparing the fields from the modified document with the original document whereas the save method updates/replaces the values of all the fields of an original document by the taking values from the modified document and setting the values into the original document.
Q : What will be the proper way to update a single document in the new (Mongo Java driver 4.7.0)
-> You should be using updateOne(query, updates, options) to update a single document on a MongoCollection object.
From updateOne docs :
The method accepts a filter that matches the document you want to
update and an update statement that instructs the driver how to change
the matching document. The updateOne() method only updates the first
document that matches the filter.
To perform an update with the updateOne() method, you must pass a
query filter and an update document. The query filter specifies the
criteria for which document to perform the update on and the update
document provides instructions on what changes to make to it.
You can optionally pass an instance of UpdateOptions to the
updateOne() method in order to specify the method's behavior. For
example, if you set the upsert field of the UpdateOptions object to
true, the operation inserts a new document from the fields in both the
query and update document if no documents match the query filter.
Q : Is it seems like it was an attempt to do UPSERT operation (Update or Insert) ?
-> Yes, it's an upsert operation.
Q : Why the code is trying to remove _id from document ?
-> The update method will update the document if the document was found by internal_id. If the document was not found and also if there is no _id field in the document, then the mongoshell will consider it as a new document and will invoke insert method internally via the update method to insert the document. For the insertion to happen, that's why it was removed from document.
Just update the code to this.
#Override
public void saveOrUpdatePrinter(Document printer) {
MongoCollection<Document> collection = mongoTemplate.getCollection("PRINTERS");
Document query = new Document().append(PRINTER_COLUMNS.internal_id, printer.get(PRINTER_COLUMNS.internal_id));
UpdateOptions options = new UpdateOptions().upsert(true);
printer.put(PRINTER_COLUMNS.updateDate,new Date());
UpdateResult result = collection.updateOne(query, printer, options);
logger.debug("saveOrUpdatePrinter updated records: " + result.getModifiedCount());
}

You can update a document using the MongoCollection#updateOne() method
An example would be:
collection.updateOne(Filters.eq("_id", new ObjectId("1234")), Updates.set("date", new Date());

Using MongoDB 3.4 to load and save userdata

How can I find a document and retrieve it if found, but insert and retrieve it if not found in one command?
I have an outline for the formats I wish my documents to look like for a user's data. Here is what it looks like
{
"username": "HeyAwesomePeople",
"uuid": "0f91ede5-54ed-495c-aa8c-d87bf405d2bb",
"global": {},
"servers": {}
}
When a user first logs in, I want to store the first two values of data (username and uuid) and create those empty values (global and servers. Both those global and servers will later on have more information filled into them, but for now they can be blank). But I also don't want to override any data if it already exists for the user.
I would normally use the insertOne or updateOne calls to the collection and then use the upsert (new UpdateOptions().upsert(true)) option to insert if it isn't found but in this case I also need to retrieve the user's document aswell.
So in a case in which the user isn't found in the database, I need to insert the outlined data into the database and return the document saved. In a case where the user is found in the database, I need to just return the document from the database.
How would I go about doing this? I am using the latest version of Mongo which has deprecated the old BasicDBObject types, so I can't find many places online that use the new 'Document' type. Also, I am using the Async driver for java and would like to keep the calls to the minimum.

How can I find a document and retrieve it if found, but insert and retrieve it if not found in one command?
You can use findOneAndUpdate() method to find and update/upsert.
The MongoDB Java driver exposes the same method name findOneAndUpdate(). For example:
// Example callback method for Async
SingleResultCallback<Document> printDocument = new SingleResultCallback<Document>() {
#Override
public void onResult(final Document document, final Throwable t) {
System.out.println(document.toJson());
}
};
Document userdata = new Document("username","HeyAwesomePeople")
.append("uuid", "0f91ede5")
.append("global", new Document())
.append("servers", new Document());
collection.findOneAndUpdate(userdata,
new Document("$set", userdata),
new FindOneAndUpdateOptions()
.upsert(true)
.returnDocument(ReturnDocument.AFTER),
printDocument);
The query above will try to find a document matching userdata; if found set it to the same value as userdata. If not found, the upsert boolean flag will insert it into the collection. The returnDocument option is to return the document after the action is performed.
The upsert and returnDocument flags are part of FindOneAndUpdateOptions
See also MongoDB Async Java Driver v3.4 for tutorials/examples. The above snippet was tested with current version of MongoDB v3.4.x.

How to update a document in MongoDB using ObjectID in Java

What I am trying to accomplish here is pretty simple. I am trying to update a single document in MongoDB collection. When I look up the document using any field, such as "name", the update query succeeds. Here is the query:
mongoDB.getCollection("restaurants").updateOne(
new BasicDBObject("name", "Morris Park Bake Shop"),
new BasicDBObject("$set", new BasicDBObject("zipcode", "10462"))
);
If I try to lookup the document with the ObjectId, it never works as it doesn't match any document.
mongoDB.getCollection("restaurants").updateOne(
new BasicDBObject("_id", "56110fe1f882142d842b2a63"),
new BasicDBObject("$set", new BasicDBObject("zipcode", "10462"))
);
Is it possible to make this query work with Object IDs?
I agree that my question is a bit similar to How to query documents using "_id" field in Java mongodb driver? however I am not getting any errors while trying to update a document. It just doesn't match anything.

You're currently trying to update based on a string, not an ObjectId.
Make sure to initialise a new ObjectId from the string when building your query:
mongoDB.getCollection("restaurants").updateOne(
new BasicDBObject("_id", new ObjectId("56110fe1f882142d842b2a63")),
new BasicDBObject("$set", new BasicDBObject("zipcode", "10462"))
);

#sheilak's answer is the best one but,
You could use {"_id", {"$oid","56110fe1f882142d842b2a63"}} as the filter for the update query if you want it to be in the string format

Convert the string to objectid:
from bson.objectid import ObjectId
db.collection.find_one({"_id":ObjectId('5a61bfadef860e4bf266edb2')})
{u'_id': ObjectId('5a61bfadef860e4bf266edb2'), ...

Mongodb avoid duplicate entries

I am newbie to mongodb. May I know how to avoid duplicate entries. In relational tables, we use primary key to avoid it. May I know how to specify it in Mongodb using java?

Use an index with the {unique:true} option.
// everyone's username must be unique:
db.users.createIndex({email:1},{unique:true});
You can also do this across multiple fields. See this section in the docs for more details and examples.
A unique index ensures that the indexed fields do not store duplicate values; i.e. enforces uniqueness for the indexed fields. By default, MongoDB creates a unique index on the _id field during the creation of a collection.
If you wish for null values to be ignored from the unique key, then you have to also make the index sparse (see here), by also adding the sparse option:
// everyone's username must be unique,
//but there can be multiple users with no email field or a null email:
db.users.createIndex({email:1},{unique:true, sparse:true});
If you want to create the index using the MongoDB Java Driver. Try:
Document keys = new Document("email", 1);
collection.createIndex(keys, new IndexOptions().unique(true));

This can be done using "_id" field although this use is discouraged.
suppose you want the names to be unique, then you can put the names in "_id" column and as you might know "_id" column is unique for each entry.
BasicDBObject bdbo = new BasicDBObject("_id","amit");
Now , no other entry can have name as "amit" in the collection.This can be one of the way you are asking for.

As of Mongo's v3.0 Java driver, the code to create the index looks like:
public void createUniqueIndex() {
Document index = new Document("fieldName", 1);
MongoCollection<Document> collection = client.getDatabase("dbName").getCollection("CollectionName");
collection.createIndex(index, new IndexOptions().unique(true));
}
// And test to verify it works as expected
#Test
public void testIndex() {
MongoCollection<Document> collection = client.getDatabase("dbName").getCollection("CollectionName");
Document newDoc = new Document("fieldName", "duplicateValue");
collection.insertOne(newDoc);
// this will throw a MongoWriteException
try {
collection.insertOne(newDoc);
fail("Should have thrown a mongo write exception due to duplicate key");
} catch (MongoWriteException e) {
assertTrue(e.getMessage().contains("duplicate key"));
}
}

Theon solution didn't work for me, but this one did:
BasicDBObject query = new BasicDBObject(<fieldname>, 1);
collection.ensureIndex(query, <index_name>, true);

I am not a Java programmer however you can probably convert this over.
MongoDB by default does have a primary key known as the _id you can use upsert() or save() on this key to prevent the document from being written twice like so:
var doc = {'name': 'sam'};
db.users.insert(doc); // doc will get an _id assigned to it
db.users.insert(doc); // Will fail since it already exists
This will stop immediately duplicates. As to multithread safe inserts under certain conditions: well, we would need to know more about your condition in that case.
I should add however that the _id index is unqiue by default.

using pymongo it looks like:
mycol.create_index("id", unique=True)
where myCol is the collection in the DB
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import pymongo
myclient = pymongo.MongoClient("mongodb://localhost:27017/")
mydb = myclient["mydatabase"]
mycol = mydb["customers"]
mycol.create_index("id", unique=True)
mydict = {"name": "xoce", "address": "Highway to hell 666", "id": 1}
x = mycol.insert_one(mydict)

Prevent mongoDB to save duplicate email
UserSchema.path('email').validate(async(email)=>{
const emailcount = await mongoose.models.User.countDocuments({email})
return !emailcount
}, 'Email already exits')
May this help ur question...
worked for me..
use in user model.
refer for explaination
THANKS...

Retrieving the UUID from Apache Solr after a commit

I am using Solrj to add new documents to a Solr instance. In my document schema the id is a UUID (solr.UUIDField). Each time a document is created the id is filled with the unique id, which is exactly what I want. Sometimes it's necessary in my application that I can retrieve this unique id to add it as a field value when inserting another document. So my question is, how can I retrieve this generated uuid from solr after adding a document?
Solrj returns me this UpdateResponse object after commiting, but I don't know how to get the new uuid out of it.
I am adding a document like this
CommonsHttpSolrServer server = new CommonsHttpSolrServer(MY_SERVER_URL);
SolrInputDocument doc = new SolrInputDocument();
// [...] multiple addField calls
server.add(doc);
UpdateResponse ur = server.commit();

AFAIK you aren't going to ever get a UUID from an add or a commit. When you do an add or commit, the update request handler gives you back query time and status, but not much else (assuming it is successful). You can actually see what is in the HTTP response by running a manual add/commit like so:
http://localhost:8983/solr/update?stream.body=<add><doc><field name="id">test</field><field name="title">test title</field></doc></add>
http://localhost:8983/solr/update?stream.body=<commit/>
If you run those queries in a web browser, they will submit a test document and commit it, respectively. You will then be able to see what information is available to SolrJ (not much).
You could write your own (modified) update handler in Java, but that seems like a ton of work. You could also enable the "timestamp" field in your Solr schema so you can query solr by last modified date and find the items you just committed.
Both of those methods would be major hacks, though. Your best bet is to figure out a unique ID for your documents before you submit them to Solr, then use that unique ID to retrieve them. Using a generated UUID is more of a "fire and forget about this" method. Since you don't want to forget, you will need to generate your own UUID.
Since you're using Java, it should be dead simple to do with UUID, using some code like this:
CommonsHttpSolrServer server = new CommonsHttpSolrServer(MY_SERVER_URL);
SolrInputDocument doc = new SolrInputDocument();
UUID uuid = UUID.randomUUID();
doc.addField("id", uuid.toString());
// [...] multiple addField calls
server.add(doc);
UpdateResponse ur = server.commit();