java 数组 mongodb_java mongoDB 二级数组嵌套查询

场景：

会员集合下有多个会员文档，会员文档下有多个订单文档，订单买了多个商品文档

member->orders>orderItems

要求：

通过会员id和商品id验证会员是否购买过该商品。

数据示例

{

"_id" : ObjectId("57e395c7a8a9b40d62008704"),

"orders" : [

{

"_id" : ObjectId("582d5633c8ddd70b75a7a050"),

"paid" : true,

"status" : "PAID",

"orderItems" : [

{

"ID" : ObjectId("582d5633c8ddd70b75a7a051"),

"requestId" : "582d5633c8ddd70b75a7a04f",

"price" : "4",

"ultimatePrice" : "4",

"quantity" : NumberInt("1")

}

]

}

]

}

mongodb语句：

db.getCollection("f.member").find({_id:ObjectId("memberId……"),"orders.paid":true,"orders":{"$elemMatch":{"orderItems":{"$elemMatch" :{"ID":ObjectId("itemId……")}}}}},{"orders.$.orderItems":1})

java代码：

BasicDBObject itemIdDbObject=new BasicDBObject("ID",itemId);

BasicDBObject itemsIdElem=new BasicDBObject().append(QueryOperators.ELEM_MATCH,itemIdDbObject);

BasicDBObject orderItemsElem=new BasicDBObject().append("orderItems",itemsIdElem);

BasicDBObject orderElem=new BasicDBObject().append(QueryOperators.ELEM_MATCH,orderItemsElem);

BasicDBObject fiedValue=new BasicDBObject();

fiedValue.put("_id",memberId);

fiedValue.put("orders.paid",true);

fiedValue.append("orders",orderElem);

BasicDBObject retrievedFields=new BasicDBObject("orders.$",1);

System.out.println(fiedValue.toJson());

DBCursor rs = this.getCollection().find(fiedValue);

DBObject explain = rs.explain();

int count = rs.count();