如何使用Java mongodb驱动程序中的“_id”字段查询文档？

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

我试图通过搜索“_id”键在MongoDB中查找文档。我的文件看起来像这样 -

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

I am trying to search this document as-

我试图搜索这份文件 -

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-

但我得到以下错误 -

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.

BasicDBObject的append方法支持(String Key,Value),如果我将“_id”作为String传递给此方法,则不匹配任何文档。

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

所以我的问题是如何通过“_id”?

4 个解决方案

#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).

不确定其他人是否可能正在搜索关于此主题的答案,但这是基于“_id”搜索MongoDB记录的最简单方法。 MongoDB文档没有更新,仍然将ObjectId显示为com.mongodb包的一部分(它通常也没有提供有关ObjectId搜索的大量信息)。

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;
}

#2

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

对于那些寻求更新方法的人,特别是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
}

#3

Solved it by using query as-

通过使用查询解决它 -

query.putAll((BSONObject)query);

#4

You can do this

你可以这样做

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

#1

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;
}

#2