How can I use variables as part of field names in the MongoDB shell?

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

Tobias Krogh · Accepted Answer · 2012-04-19 17:47:53Z

8

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;

answered Apr 19, 2012 at 17:47

Tobias Krogh

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1 Comment

OG Dude Over a year ago

Thanks, that worked

var site = "google.com"; var y = 2012; var m = 10; var d = 30; doc = {}; incDoc["counts.year."+y] = 1; incDoc["counts.month."+m] = 1; incDoc["counts.days."+d] = 1; db.test.update({ "domain" : site}, { $inc : incDoc}, upsert=true);

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