非规范化模型中的MongoDB查询

Question

我必须展示使用规范化模型的优势(在本例中)，在MongoDB中有两个集合:第一个用于教练，第二个用于团队。所以，我用一个非正态化的模型来显示这些差异。例如，如果我想更新巴切洛纳的手掌(从23西甲到24西甲)，用非正规化的模式，我必须找到所有教练巴切洛纳，然后我必须更新每个教练的手掌。显然太贵了。我想做这个例子。

我有一个他们所指导的足球教练和球队的非正规化模型。下面是一个示例：

     "_id" : "LEMG_1970",
  "name" : "Luis",
  "surname" : "Enrique Martinez Garcia",
  "age" : 45,
  "date_Of_birth" : {
          "day" : 8,
          "month" : 5,
          "year" : 1970
  },
  "place_Of_birth" : "Gijòn",
  "nationality" : "Spanish",
  "preferred_formation" : "4-3-3 off",
  "coached_Team" : [
          {


"_id" : "Bar.43",
   "official_name" : "Futbol Club Barcelona"
   "common_name" : "Barcellona",
   "country" : "Spain",
   "started_by" : {
           "day" : 28,
           "month" : 11,
           "year" : 1899
   },
   "championship" : "La Liga",
   "stadium" : {
           "name" : "Camp Nou",
           "capacity" : 99354
   },
   "palmarès" : {
           "La Liga" : 23,
           "Copa del Rey" : 27,
           "Supercopa de Espana" : 11,
           "UEFA Champions League" : 4,
           "UEFA Cup Winners Cup" : 4,
           "UEFA Super Cup" : 4,
           "FIFA Club World cup" : 2
   },
   "average age" : 26.9,
   "squad value(in mln)" : 591.5,
   "foreigners" : 13,
   "uniform" : [
           "blue",
           "dark red"
   ],
                  "in_charge" : {
                          "from" : {
                                  "day" : 1,
                                  "month" : 7,
                                  "year" : 2014
                          }
                  },
                  "matches" : 59
          },
          {

          {
         "_id" : "Rom.01",
   "official_name" : "Associazione Sportiva Roma SpA",
   "common_name" : "Roma",
   "country" : "Italy",
   "started_by" : {
           "day" : 22,
           "month" : 6,
           "year" : 1927
   },
   "championship" : "Serie A",
   "stadium" : {
           "name" : "Olimpico di Roma",
           "capacity" : 73261
   },
   "palmarès" : {
           "Serie A" : 3,
           "Coppa Italia" : 9,
           "Supercoppa Italiana" : 2,
           "Serie B" : 1
   },
   "average age" : 28.3,
   "squad value(in mln)" : 253.7,
   "foreigners" : 22,
   "uniform" : [
           "red",
           "yellow"
   ],
                  "in_charge" : {
                          "from" : {
                                  "day" : 7,
                                  "month" : 6,
                                  "year" : 2011
                          },
                          "to" : {
                                  "day" : 10,
                                  "month" : 5,
                                  "year" : 2012
                          }
                  },
                  "matches" : 41
          }
  ]

正如你所看到的，关于球队的信息被写入教练文档中。现在，我想更新巴塞罗纳的掌纹。我尝试了这个查询，但是我得到了一个错误：

 db.coach.update({_id:"LEMG_1970"}, {$set:{"coached_Team.palmarès.La Liga":24}})

以下是建议：

"code" : 16837,
            "errmsg" : "cannot use the part (coached_Team of coached_Team.palmarès.La Liga) to traverse the element

我能做些什么来用非正规化模型来更新手掌呢？

Answer 1

使用更新中的positional operator，这将标识要更新的数组中的元素，而无需显式指定元素在数组中的位置。由于位置$运算符充当与查询文档匹配的第一个元素的占位符，因此数组字段必须显示为查询文档的一部分，因此在查询中需要coached_Team数组字段：

var query = {
        "_id" : "LEMG_1970",
        "coached_Team._id" : "Bar.43"
    },
    update = {
        "$set": {
            "coached_Team.$.palmarès.La Liga": 24
        }
    };

db.coach.update(query, update);