如何 return MongoDB 中没有 objectId 的集合的文档？

Question

DB db = mongo.getDB("sample");
DBCollection table = db.getCollection("samplecollection");
DBCursor cursor2 = table.find();

给出的结果为： { “_id”：{ “$oid”：“58bfbcff1d30d8a8c1194328”}，"ID"：1，"NAME"："dgsdg"}

如何获取没有objectid的文档？

Answer 1

您可以使用 projection。

试试这个：

DBCursor cursor2 = table.find().projection(excludeId())

阅读 this MongoDB 文档以了解更多信息。

Answer 2

你可以使用聚合框架来实现你想要的：

db.getCollection('samplecollection').aggregate([{$project: { field1:1 ,field2: 1......,'_id': 0} }])

https://docs.mongodb.com/manual/reference/operator/aggregation/project/

Answer 3

我已经完成并工作了：

MongoDatabase database = mongo.getDatabase("db");
     MongoCollection<org.bson.Document> contCol = database.getCollection("test");
     FindIterable<org.bson.Document> it = contCol.find().projection(excludeId());
     ArrayList<Document> docs = new ArrayList();


       for (org.bson.Document its : it) {
           System.out.println(its);
       }

Answer 4

首先你要导入这个，导入com.mongodb.client.model.Projections;

那你也试试这个吧..

MongoClient client = new MongoClient("hostName");
MongoDatabase db = client.getDatabase("dbName");
MongoCollection<Document> collection = db.getCollection("collectionName");
collection.withWriteConcern(new WriteConcern(1));
/*   whatever field you dosn`t need.. you will run this following code, 

        FindIterable<Document> findDoc = collection.find().projection(new Document().append("_id",0));  //if you need mean, you put _id value is 1.

    */
FindIterable<Document> findDoc = collection.find().projection(Projections.excludeId()) ;
 for (Document doc : findDoc) {
       System.out.println(doc);
   }

如何 return MongoDB 中没有 objectId 的集合的文档？

How to return documents of a collection without objectId in MongoDB?

java

mongodb

mongodb-java