貓鼬，$ setIsSubset

Question

權之前對象的過濾器列表現在我有這樣的

ObjectWithElement.aggregate([{ 
     $redact: { 
     '$cond': [ 
      { 
      '$eq': [ 
       { $setIsSubset: ['$elements.element', myElements] }, true 
      ] 
      }, 
      '$$KEEP', 
      '$$PRUNE' 
     ] 
     } 
    } 
    ]).exec(listCallback); 

元的方案是聚集：

var ElementSchema = new Schema({ 
    name: { 
     type: String, 
     default: '', 
     required: 'Please fill name', 
     trim: true 
    }, 
    importance: { 
     type: String, 
     default: 'Medium', 
     enum: ['Low', 'Medium', 'High'] 
    }, 
    user: { 
     type: Schema.ObjectId, 
     ref: 'User' 
    } 
    }, 
    { 
    timestamps: true 
    }); 

但我想過濾「$ elements.element '通過只保留具有「高」或「中」重要性的元素

如何過濾這些元素，因爲$ setIsSubset操作？

一些數據：

MyElements

{ 
    "_id" : ObjectId("5834b78271dc8b8c24cec6aa"), 
    "user" : ObjectId("581108f40e10a7e846456737"), 
    "elements" : [ 
     { 
      "element" : ObjectId("581b7c645057c4602f48627f"), 
      "quantity" : 1, 
      "unit" : ObjectId("581ca0da5b1e3058521a6d8b"), 
      "_id" : ObjectId("58540ddb431dc71048974e61") 
     } 
    ], 
    "__v" : 9, 
    "createdAt" : ISODate("2016-11-22T21:24:18.000Z"), 
    "updatedAt" : ISODate("2016-12-16T15:52:59.841Z") 
} 

---

元素

{ 
    "_id" : ObjectId("581b7c645057c4602f48627f"), 
    "user" : ObjectId("581108f40e10a7e846456737"), 
    "importance" : "High", 
    "name" : "Element1", 
    "__v" : 0, 
    "createdAt" : ISODate("2016-11-03T18:05:24.000Z"), 
    "updatedAt" : ISODate("2016-12-15T21:40:03.502Z") 
}, 
{ 
    "_id" : ObjectId("581ca0e75b1e3058521a6d8c"), 
    "user" : ObjectId("581108f40e10a7e846456737"), 
    "importance" : "Low", 
    "name" : "Element2", 
    "__v" : 0 
    "createdAt" : ISODate("2016-11-03T18:05:26.000Z"), 
    "updatedAt" : ISODate("2016-12-15T21:44:03.502Z") 
} 

---

ObjectWithElements

{ 
    "_id" : ObjectId("582e1b627836bcc045c06325"), 
    "user" : ObjectId("581108f40e10a7e846456737"), 
    "name" : "Object1", 
    "elements" : [ 
     { 
      "element" : ObjectId("581b7c645057c4602f48627f"), 
      "quantity" : 1, 
      "unit" : ObjectId("581ca0da5b1e3058521a6d8b"), 
      "_id" : ObjectId("582e1b627836bcc045c06328") 
     }, 
     { 
      "element" : ObjectId("581ca0e75b1e3058521a6d8c"), 
      "quantity" : 1, 
      "unit" : ObjectId("581ca0da5b1e3058521a6d8b"), 
      "_id" : ObjectId("58530046cfc0c384010f0839") 
     } 
    ], 
    "__v" : 2, 
    "createdAt" : ISODate("2016-11-17T21:04:34.000Z"), 
    "updatedAt" : ISODate("2016-12-15T20:42:46.843Z") 
}, 
{ 
    "_id" : ObjectId("582e2c05b4e900d03d494fef"), 
    "user" : ObjectId("581108f40e10a7e846456737"), 
    "name" : "Object2", 
    "elements" : [ 
     { 
      "element" : ObjectId("581b7c645057c4602f48627f"), 
      "quantity" : 2, 
      "unit" : ObjectId("581ca0da5b1e3058521a6d8b"), 
      "_id" : ObjectId("582e2c05b4e900d03d494ff2") 
     } 
    ], 
    "__v" : 2, 
    "createdAt" : ISODate("2016-11-17T22:15:33.000Z"), 
    "updatedAt" : ISODate("2016-12-15T20:42:59.999Z") 
} 

Answer 1

您可以

{ 
    $setIsSubset: [{ 
      $filter: { 
       input: "$elements.element", 
       as: "element", 
       "cond": { 
        $setIsSubset: [['$$element.importance'], ['High', 'Medium']] 
       } 
      } 
     }, 
     myElements 
    ] 
}