MongoDB 分组查询（Group）

集合：collectTest
{
    "_id" : NumberLong("908531627875254272"),
    "_class" : "com.XXXX",
    "tripId" : NumberLong("908531628206604288"),
    "userId" : NumberLong("888236517070209024"),
    "payAmount" : "77.80",
    "orderPrice" : "77.80",
    "couponValue" : "0",
    "insurancePrice" : "0",
    "payType" : "BALANCE",
    "orderStatus" : "CANCELED",
    "payStatus" : "NOT_NEED_PAY",
    "paidTime" : ISODate("2017-09-15T12:29:26.035+08:00"),
    "orderCode" : "cra20170915000001",
    "createTime" : ISODate("2017-09-15T11:23:14.522+08:00")
}

分组查询如下：

类似与 sql中的 select userId,count(*) from tableName group by userId;

db.collectTest.aggregate([
    { 
          $match: {
            "userId": NumberLong("888236517070209024"),
            "orderStatus": "CANCELED"
         }
    },
    {
        $group: {
            _id: "$userId",
            count: {
                $sum: 1
            }
        }
    }
]);

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一些聚合的表达式请参考 这里写链接内容

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在 java 中使用MongoTemplate 的调用方式如下：

 public void groupTest(){
        List<DBObject> list = Lists.newArrayList(new BasicDBObject("$match", new BasicDBObject("orderStatus", "CANCELED")
                .append("userId",888236517070209024L)

        ),new BasicDBObject("$group",new BasicDBObject("_id","$userId").append("total", new BasicDBObject("$sum",1)))

        );
        Cursor cursor = mongoTemplate.getCollection("collectTest").aggregate(list, AggregationOptions.builder().build());

        while (cursor.hasNext()){
            cursor.next();
        }
    }