Update Object at Specific Array Index in MongoDB

Question

I have a collection of the form

{ id : 1,
  data: [ [ { name : "alice" }, { name : "bob" } ],
          [ { name : "dan" },   { name : "rob" } ] ] }

and the structure of the array has meaning. How would I update the first element ([0][0]) and set name = "alex". I've seen many questions addressing how to update array elements that match a query but not specific elements. To be clear, after the update, the record should look like this:

{ id : 1,
  data: [ [ { name : "alex" },  { name : "bob" } ],
          [ { name : "dan" },   { name : "rob" } ] ] }

BatScream · Accepted Answer · 2015-01-19 00:44:15Z

6

Assuming, you have created the structure with some purpose, which ideally becomes tougher to query, you could update it by specifying the index explicitly:

db.collection.update({"id":1},{$set:{"data.0.0.name":"alex"}})

answered Jan 19, 2015 at 0:44

BatScream

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Virendra Singh · Accepted Answer · 2018-04-04 10:44:11Z

1

If we don't have a fixed position and is known at runtime or Dynamic then this approach works perfectly

var setObject = {};
setObject["board."+ x +"."+ y] = player;
gamesColl.update({_id: realId},{
$set:setObject
}, function(err,doc){
console.log(err,doc);
});

answered Apr 4, 2018 at 10:44

Virendra Singh

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Uptimist · Accepted Answer · 2022-05-27 08:58:05Z

0

you can go further!! if you want to paste indexes as a variable use string template like this

db.collection.update({"id":1},{$set:{[`data.${index}.${index}.name`]:"alex"}})

answered May 27, 2022 at 8:58

Uptimist

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