MongoDB with Java

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我正在尝试使用 java 为 MongoDB 传输 PostgreSQL.

i am trying transfer the PostgreSQL for MongoDB using java.

我有 SQL

SELECT id_buyer, buyer, SUM(qtde) FROM test.log GROUP BY id_buyer, buyer

和我的新代码

MongoClient mongoClient = new MongoClient(); MongoDatabase db = mongoClient.getDatabase("teste"); MongoCollection<Document> coll = db.getCollection("log"); DBObject groupFields = new BasicDBObject(); groupFields.put("id_buyer", "$id_buyer"); groupFields.put("buyer", "$buyer"); AggregateIterable<Document> mongoCollectionList = coll.aggregate( Arrays.asList( Aggregates.group(groupFields, Accumulators.sum("qtde", "$qtde")), Aggregates.project(fields(include("comprador", "Quantidade"))) )); MongoCursor<Document> mongoCursor = mongoCollectionList.iterator(); while (mongoCursor.hasNext()) { System.out.println(mongoCursor.next().toJson()); }

结果

{ "_id" : { "id_buyer" : 2, "buyer" : "COMPS" }, "qtde" : 16703 }

如何删除_id"中的id_buyer"和buyer"?

How do i remove "id_buyer" and "buyer" that is into "_id" ?

谢谢

推荐答案

我已经测试了 答案 由 Veeram 发布，它非常适合我.

I have tested the answer posted by Veeram and it worked perfectly for me.

这是他的建议:

Aggregates.project(fields(excludeId(), computed("id_buyer", "$_id.id_buyer"), computed("buyer", "$_id.buyer"), include("comprador", "Quantidade")));