使用 mongodb 中的条件将字段添加到集合中

Question

我想将一个新的布尔字段添加到包含其他字段信息的集合中。

我的样本数据是；

{ 
    "_id" : ObjectId("50abae61edecb53c740022eb"), 
    "pull_request" : {
        "diff_url" : null, 
        "patch_url" : null, 
        "html_url" : null
    }
}
{ 
    "_id" : ObjectId("50abae61edecb53c740022ec"), 
    "pull_request" : {
        "diff_url" : "https://github.com/joyent/http-parser/pull/106.diff", 
        "patch_url" : "https://github.com/joyent/http-parser/pull/106.patch", 
        "html_url" : "https://github.com/joyent/http-parser/pull/106"
    }, 
} 

新字段是“hasPullRequest”；如果 pull_request 字段为空，则 hasPullRequest:false; 否则 hasPullRequest:true。我的意思是下面的；

{ 
    "_id" : ObjectId("50abae61edecb53c740022eb"), 
    "pull_request" : {
        "diff_url" : null, 
        "patch_url" : null, 
        "html_url" : null
    },
    "hasPullRequest" : false
}
{ 
    "_id" : ObjectId("50abae61edecb53c740022ec"), 
    "pull_request" : {
        "diff_url" : "https://github.com/joyent/http-parser/pull/106.diff", 
        "patch_url" : "https://github.com/joyent/http-parser/pull/106.patch", 
        "html_url" : "https://github.com/joyent/http-parser/pull/106"
    }, 
    "hasPullRequest" : true
} 

我尝试了这个查询，但它没有运行；

db.getCollection('issues').aggregate([
   {
     $addFields: {
       hasPullRequest:  { 
            "$cond": {
            if: { { "$eq": {"$pull_request": null}} ,
            then: false,
            else: true
            } 
      }
   }
])

我怎样才能做到这一点？

Answer 1

由于有些记录没有pull_request字段，所以我添加了一个or条件；

    db.getCollection("test").aggregate( [ 
  { 
      $addFields: { 
          hasPullRequest: { 
             $cond: [ 
                 { 
                     $or:
                     [ 
                         { $and: [ 
                            { $eq: [ "$pull_request.diff_url", null ] },
                            { $eq: [ "$pull_request.patch_url", null ] },
                            { $eq: [ "$pull_request.html_url", null ] },
                                 ]
                         },
                         {  $eq:[{ $ifNull: [ "$pull_request", 0 ] },0]  }
                      ]
                  },
                 false, 
                 true 
             ] 
          } 
      } 
  },
  {
        $out: "Issues2"
  }
]
).pretty()

它对我来说非常有效。

Answer 2

问题在于您的查询条件 - { "$eq": {"$pull_request": null}}。它应该是以下之一：

db.test.aggregate( [ 
  { 
      $addFields: { 
          hasPullRequest: { 
             $cond: [ 
                 { $eq: [ "$pull_request", { diff_url: null, patch_url: null, html_url: null } ] }, 
                 false, 
                 true 
             ] 
          } 
      } 
  }
] ).pretty()

db.test.aggregate( [ 
  { 
      $addFields: { 
          hasPullRequest: { 
             $cond: [ 
                 { $and: [ 
                        { $eq: [ "$pull_request.diff_url", null ] },
                        { $eq: [ "$pull_request.patch_url", null ] },
                        { $eq: [ "$pull_request.html_url", null ] }
                 ] },
                 false, 
                 true 
             ] 
          } 
      } 
  }
] ).pretty()

[ 编辑添加 ]

db.test.aggregate( [ 
  { 
      $facet: {
           pull_req_no: [
               { $match: { pull_request: { $exists: false } } },
               { $addFields: { hasPullRequest: false } }
           ],
           pull_req_yes: [
               { $match: { pull_request: { $exists: true } } },
               { $addFields: { 
                      hasPullRequest: {
                          $cond: [ 
                              { $and: [ 
                                  { $eq: [ "$pull_request.diff_url", null ] },
                                  { $eq: [ "$pull_request.patch_url", null ] },
                                  { $eq: [ "$pull_request.html_url", null ] }
                              ] },
                              false, 
                              true
                          ]
                      }  
               } }
           ]
      }
  },
  {
      $project: { result: { $concatArrays: [ "$pull_req_no", "$pull_req_yes" ] } }
  },
  { 
      $unwind: "$result" 
  },
  { 
      $replaceRoot: { newRoot: "$result" } 
  }
] ).pretty()