MongoDB十进制舍入

Question

我使用了词素对MongoDB进行数据聚合。但我需要四舍五入汇总管道投影数据。我的代码是

 aggregationPipeline.project(
            Projection.projection("_id").suppress(),
            Projection.projection("query", "_id.query"),
            Projection.projection("clicks", "clicks"),
            Projection.projection("impressions", "impressions"),
            Projection.projection("ctr",  "ctr"),
            Projection.projection("position", "position")
);

我的输出是

{
        "query": "google",          
        "clicks": 5,
        "impressions": 16,
        "ctr": 0.19375,
        "position": 3.39375,          
},

但我希望

{
        "query": "google",          
        "clicks": 5,
        "impressions": 16,
        "ctr": 0.19,
        "position": 3.39,          
},