MongoError: Unbekannter Name der Pipelinestufe: '$ addFields'

Question

MongoError: Unbekannter Name der Pipelinestufe: '$ addFields'. "Mungo": "^ 4.5.8" Mein Sourcecode:

   Post.aggregate(
        [{ 
         $addFields: { 
          userName: { $concat: [ "$author.firstName", " ", "$author.lastName" ] } 
         } 
         //$project: { userName: { $concat: [ "$author.firstName", " ", "$author.lastName" ] } } //this is ok! 
        }], 
        function (err, result) { 
         if (err) { 
          console.log(err); 
          return; 
         } 
         console.log(result); 
        } 
       ) 

Beitrag Modell:

let schema = { 
id: "post", 
properties: { 
    content: {type: "string"}, 
    author: { 
     type: "object", 
     id: {type: "string"}, 
     avatar: {type: "string"}, 
     firstName: {type: "string"}, 
     lastName: {type: "string"}, 
     status: {type: "string"} 
    }, 
    category: { 
     type: "object", 
     id: {type: "string"}, 
     name: {type: "string"} 
    }, 
    images: { 
     type: "array", 
     items: { 
      type: "object", 
      properties: { 
       filePath: {type: "string"}, 
      } 
     } 
    }, 
    video: { 
     type: "object", 
     thumbnail: {type: "string"}, 
     filePath: {type: "string"} 
    }, 
    likes: { 
     type: "array", 
     items: { 
      type: "object", 
      properties: { 
       userId: {type: "string"}, 
       status: {type: "string"}, 
       _id : {type: "string", default: null} 
      } 
     } 
    }, 
    shares: { 
     type: "array", 
     items: { 
      type: "object", 
      properties: { 
       userId: {type: "string"}, 
       status: {type: "string"}, 
       destination: {type: "string"}, //FACEBOOK|TWISTER|GOOGLE 
       _id  : {type: "string", default: null} 
      } 
     } 
    }, 
    favorites: { 
     type: "array", 
     items: { 
      type: "object", 
      properties: { 
       userId: {type: "string"}, 
       status: {type: "string"}, 
       _id : {type: "string", default: null} 
      } 
     } 
    }, 
    comments: { 
     type: "array", 
     items: { 
      type: "object", 
      properties: { 
       commentId: {type: "string"}, 
       _deleted: {type: "Date", default: ''}, 
       _id  : {type: "string", default: null} 
      } 
     } 
    }, 
    _created: {type: "Date", default: Date.now}, 
    _deleted: {type: "Date", default: ''}, 
    _updated: {type: "Date", default: ''} 
} 

Answer 1

$addFields wird in Mongo 3.4 Version eingeführt. Nachdem Sie bemerkt haben, dass Sie mongo 3.2.9 verwenden, wird die erwähnte Abfrage nicht funktionieren.

Wenn Sie nicht die Mongo Version aus irgendeinem Grund aktualisieren, dann müssen Sie folgende Vorgehensweise verwenden, in denen Sie über jedes Dokument zu durchlaufen müssen und legen Sie das neue Feld

Post.find({}).forEach(function(post){ 
    post.findOneAndUpdate({_id: post._id}, 
     {$set: {userName: post.author.firstName + " " + post.author.lastName }}) 
});