CODEWITHSUNDEEP
arraysmongodbmongodb-update
HaiFengZeng
HaiFengZeng

Reputation: 103

push elements into array

I have a collection named test looks like the following json:

{
   '_id':ObjetcId("..."),
   'a':[
        {
          id:1,
          a1:[{x:1,y:1},{x:10,y:11},{x:10,y:12}],
          flag:1
        },
        { 
          id:2
          a1:[{x:1,y:1},{x:10,y:11},{x:10,y:12}],
          flag:0
        },
       ]
}

Now I want to push an another ({x：99，y:99}) element into a.a1 with condition that a.id=1, I tried the command:

db.test.update({'_id':ObjectId('...')},{"$push":{"a.a1":{x:99,y:99}}})

and return error message that can't use the part(a of a.a1 ) to traverse the elements,so how should I add the element to the array?

Upvotes: 0

Views: 37

Answers (1)

Jairo Malanay
Jairo Malanay

Reputation: 1347

mongodb positional/$ The positional $ operator identifies an element in an array to update without explicitly specifying the position of the element in the array. To project, or return, an array element from a read operation, see the $ projection operator.

db.test.update({ 
    _id: ObjectId('...'),
    "a.id": 1 
}, { 
    $push: { 
        "a.$.a1": { x: 99, y: 99 } 
    } 
})

Upvotes: 1

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