Question

How can I use variables as part of field names in the mongodb shell? I am trying to do the following:

> var site = "google.com";
> var y = 10;
> var m = 5;

// This fails (field names as concatenation):
> db.test.update({ "domain" : site},
      { $inc : {"counts.year."+y : 1, "counts.month."+m : 1}}, upsert=true);

> Thu Apr 19 19:12:56 SyntaxError: missing : after property id (shell):1

// This works:
> db.test.update({ "domain" : site}, { $inc : {"counts.year.10" : 1,
      "counts.month.5" : 1}}, upsert=true);

I guess the problem is in the way the JS object is created: for instance var t = 10; doc = {t : 0}; works but var t = 10; doc = {"Test."+t : 0}; does not. How can I work around this?

Thank you,

/David

Answer 1

you could try for the JS object:

var t = 10;
var doc = {};
doc["Test."+t] = 0;

or

var t = 10, doc = {};
doc["Test."+t] = 0;