How can I update an array in a mongoDB document by index, which is stored in a variable?
{
_id: 'IDString',
field: [ bla, bla, old, bla ];
}
let i = 2;
Collection.update(
{ _id: 'IDString' },
{ $set:
{ 'field.$.i': 'new' }
}
);
So the result should be:
{
_id: 'IDString',
field: [ bla, bla, new, bla ];
}
My code wouldn't work, as I want to use the variable i.
Use the dot notation syntax to set up your update document since this will access an element of an array by the zero-based index position. You would have to concatenate the array name with the dot (.) and zero-based index position, and enclose in quotes.
So in your example, you would need to set up the update document dynamically to produce
var update = { "$set": { "field.2": "new" } }
The following code snippet shows this:
var i = 2,
update = { "$set": {} };
update["$set"]["field."+i] = "new";
db.collection.update({ "_id": "IDString" }, update)
var i = 2; var arr_update_dict = { "$set": {} }; arr_update_dict["$set"]["field."+i] = "new"; db.collection.update({ "_id": "IDString" }, arr_update_dict) Collection.update(
{ _id: 'IDString', field.2 : 1 },
{ $set: {
"field.$" : "new" }
}
)
This should work, if not - comment below
