How to query documents using "_id" field in Java mongodb driver?

Question

I am trying to find documents in MongoDB by searching on "_id" key. My document looks like this-

{   "_id" : ObjectId("4f693d40e4b04cde19f17205"),   "hostname" : "hostnameGoesHere",   "OSType" : "OSTypeGoesHere" } 

I am trying to search this document as-

ObjectId id= new ObjectId("4f693d40e4b04cde19f17205");         BasicDBObject obj = new BasicDBObject();         obj.append("_id", id);         BasicDBObject query = new BasicDBObject();         query.putAll(query); 

But I get below error-

error: reference to putAll is ambiguous, both method putAll(Map) in BasicBSONObject and method putAll(BSONObject) in BasicBSONObject match         query.putAll(query); 

The append method of BasicDBObject supports (String Key, Value) and if I pass "_id" as String to this method, no documents are matched.

So my question is how do I pass "_id"?

Answer 1

Not sure if others might be searching for answers on this topic, but here is the easiest way to search for a MongoDB record based on "_id". The MongoDB documentation is not updated and still shows ObjectId as being part of the com.mongodb package (it also generally does not give a lot of information on searching by ObjectId).

import org.bson.types.ObjectId;  public DBObject findDocumentById(String id) {      BasicDBObject query = new BasicDBObject();     query.put("_id", new ObjectId(id));      DBObject dbObj = collection.findOne(query);     return dbObj; } 

Answer 2

For those who are seeking a more up to date method, especially with 3.4:

import com.mongodb.client.MongoCollection; import com.mongodb.client.MongoDatabase; import org.bson.Document; import org.bson.types.ObjectId;  import static com.mongodb.client.model.Filters.eq;  //...... MongoCollection<Document> myCollection = database.getCollection("myCollection"); Document document = myCollection.find(eq("_id", new ObjectId("4f693d40e4b04cde19f17205"))).first(); if (document == null) {     //Document does not exist } else {     //We found the document }