有多个$ COND MongoDB的输出领域

Question

这里的文件一个例子，我用：

{ 
    "_id" : ObjectId("554a1f5fe36a768b362ea5c0"), 
    "store_state" : 1, 
    "services" : [ 
     { 
      "id" : "XXX", 
      "state" : 1, 
      "active": true 
     }, 
     { 
      "id" : "YYY", 
      "state" : 1, 
      "active": true 
     }, 
     ... 
    ] 
} 

我要输出与“Y”一个新的领域，如果id为“XXX”和积极的真实，“N “在任何其他情况下。每个文档都没有“XXX”作为标识的服务元素（在这种情况下，输出“N”）。

这里是我的时刻查询：

db.stores.aggregate({ 
    $match : {"store_state":1} 
}, 
{ $project : { 
    "XXX_active": { 
     $cond: [ { 
      $and:[ 
       {$eq:["services.$id","XXX"]}, 
       {$eq:["services.$active",true]} 
      ]},"Y","N" 
     ] } 
    } 
}).pretty() 

但它总是输出"N"为"XXX_active"领域。

预期输出我需要的是：

{ 
    "_id" : ObjectId("554a1f5de36a768b362e7e6f"), 
    "XXX_active" : "Y" 
}, 
{ 
    "_id" : ObjectId("554a1f5ee36a768b362e9d25"), 
    "XXX_active" : "N" 
}, 
{ 
    "_id" : ObjectId("554a1f5de36a768b362e73a5"), 
    "XXX_active" : "Y" 
} 

的可能结果的其它例子：

{ 
    "_id" : ObjectId("554a1f5de36a768b362e7e6f"), 
    "XXX_active" : "Y", 
    "YYY_active" : "N" 
}, 
{ 
    "_id" : ObjectId("554a1f5ee36a768b362e9d25"), 
    "XXX_active" : "N", 
    "YYY_active" : "N" 
}, 
{ 
    "_id" : ObjectId("554a1f5de36a768b362e73a5"), 
    "XXX_active" : "Y", 
    "YYY_active" : "Y" 
} 

只有一个每个对象XXX_active并没有重复对象，但我需要一个XXX_active即使所有对象服务id元素“XXX”不存在。有人可以帮忙吗？

Answer 1

首先$unwindservices数组，然后如下面使用$cond：

db.stores.aggregate({ 
    "$match": { 
     "store_state": 1 
    } 
}, { 
    "$unwind": "$services" 
}, { 
    "$project": { 
     "XXX_active": { 
      "$cond": [{ 
       "$and": [{ 
        "$eq": ["$services.id", "XXX"] 
       }, { 
        "$eq": ["$services.active", true] 
       }] 
      }, "Y", "N"] 
     } 
    } 
},{"$group":{"_id":"$_id","XXX_active":{"$first":"$XXX_active"}}}) //group by id 

Answer 2

以下聚合管线将给出所需的结果。您需要首先将$unwind运算符应用于services阵列字段，作为您的初始聚合管道步骤。这将从输入文档中解构services数组字段以输出每个元素的文档。每个输出文档用一个元素值替换数组。

db.stores.aggregate([ 
    { 
     "$match" : {"store_state": 1} 
    }, 
    { 
     "$unwind": "$services" 
    }, 
    { 
     "$project": { 
      "store_state" : 1, 
      "services": 1, 
      "XXX_active": { 
       "$cond": [ 
        { 
         "$and": [ 
          {"$eq":["$services.id", "XXX"]}, 
          {"$eq":["$services.active",true]} 
         ] 
        },"Y","N" 
       ] 
      } 
     } 
    }, 
    { 
     "$match": { 
      "services.id": "XXX" 
     } 
    }, 
    { 
     "$group": { 
      "_id": { 
       "_id": "$_id", 
       "store_state": "$store_state", 
       "XXX_active": "$XXX_active" 
      }, 
      "services": { 
       "$push": "$services" 
      } 
     } 
    }, 
    { 
     "$project": { 
      "_id": "$_id._id", 
      "store_state" : "$_id.store_state", 
      "services": 1, 
      "XXX_active": "$_id.XXX_active" 
     } 
    } 
])