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invzbl3
Asked:2020-06-10 05:21:33 +0800 CST2020-06-10 05:21:33 +0800 CST

MongoDB 中的示例问题

  • 772

集合中文档的结构如下：

{
        "_id" : ObjectId("569190cd24de1e0ce2dfcd62"),
        "title" : "Star Trek II: The Wrath of Khan",
        "year" : 1982,
        "rated" : "PG",
        "released" : ISODate("1982-06-04T04:00:00Z"),
        "runtime" : 113,
        "countries" : [
                "USA"
        ],
        "awards" : {
                "wins" : 2,
                "nominations" : 9,
                "text" : "2 wins & 9 nominations."
        }
}

我正在尝试使用投影并添加几个附加参数来获取特定字段的内容。我想使用这些键title, year,rated和awards指定的值。（_id 已删除）

我 db.movieDetails.find( {}, {title: 1, year: 2013, rated: "PG-13", _id: 0, "awards.wins": 1 }).pretty()以获取具有值的字段的方式对其进行了规定，但在控制台中它的显示不一致：

{
        "title" : "Once Upon a Time in the West",
        "year" : 1968,
        "rated" : "PG-13",
        "awards" : {
                "wins" : 4
        }
}
{
        "title" : "A Million Ways to Die in the West",
        "year" : 2014,
        "rated" : "R",
        "awards" : {
                "wins" : 0
        }
}
{
        "title" : "Wild Wild West",
        "year" : 1999,
        "rated" : "PG-13",
        "awards" : {
                "wins" : 10
        }
}

我想要这个：

 {
            "title" : "Once Upon a Time in the West",
            "year" : 2013,
            "rated" : "PG-13",
            "awards" : {
                    "wins" : 0
            }
    }
    {
            "title" : "A Million Ways to Die in the West",
            "year" : 2013,
            "rated" : "PG-13",
            "awards" : {
                    "wins" : 0
            }
    }
    {
            "title" : "Wild Wild West",
            "year" : 2013,
            "rated" : "PG-13",
            "awards" : {
                    "wins" : 0
            }
    }

请告诉我，请求中需要更正哪些内容才能根据我的要求输出？

mongodb

1 个回答

  1. Best Answer

    最后，就我而言，这是这样决定的：

     db.movieDetails.aggregate([
      {
        $project: {
          title: 1,
          _id: 0,
          year: "2013",
          rated: "PG-13",
          "awards.wins": "0"
        }
      }
    ]).pretty()

    或者像这样针对特定请求：

    db.movieDetails.find({year : 2013, rated:"PG-13", "awards.wins": 0},{title: 1, year:1 , rated: 1, _id: 0,awards:1, "awards.wins": 1 }).pretty()
    • 0

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