Adding new field to the document in the array of documents-CodePudding

I have mongo document like that:

{                                                                                                                               
  "_id" : ObjectId("61b4cd63465cd7ace1e12341"),                                                                           
  "artist" : "Short",                                                                                                     
  "album" : "Track",                                                                                                      
  "tracks" : [                                                                                                                    
          {                                                                                                                              
             "title" : "100m",                                                                                                       
             "length" : 10                                                                                                   
          },                                                                                                                      
          {                                                                                                                               
             "title" : "200m",                                                                                                       
             "length" : 20,                                                                                                          
             "guest" : "Big Bad"                                                                                             
          }                                                                                                               
     ]                                                                                                               
}

I'm trying to add field quest to the tracks array with title 100m. So that a document looks like that:

{                                                                                                                               
  "_id" : ObjectId("61b4cd63465cd7ace1e12341"),                                                                           
  "artist" : "Short",                                                                                                     
  "album" : "Track",                                                                                                      
  "tracks" : [                                                                                                                    
          {                                                                                                                              
             "title" : "100m",                                                                                                       
             "length" : 10,
             "guest": : "John Travolta"                                                                                                   
          },                                                                                                                      
          {                                                                                                                               
             "title" : "200m",                                                                                                       
             "length" : 20,                                                                                                          
             "guest" : "Big Bad"                                                                                             
          }                                                                                                               
     ]                                                                                                               
}

I was tryin got achive that using db.collection.update and $set, but no good results.

How can I achieve that?

CodePudding user response：

You have to use positional operator $ like this:

db.collection.update({
  "tracks.title": "100m"
},
{
  "$set": {
    "tracks.$.guest": "John Travolta"
  }
})

This query tells to mongo "For the element into the tracks array where the title is 100m, insert the field guest with value John Travolta". And all of this using $ and the query stage "tracks.title": "100m"

Example here