MongoDb Variable to String

Question

In MongoDb Shell

db.keyword.update({"state":"UT"}, {$unset:{'abc.def':1}});

unsets removes def from abc . However, if I do it like this :

var key = 'def'

var key1 = 'abc.'+key 
db.keyword.update({"state":"UT"}, {$unset:{key1:1}});

doesnt unset def.

How do I get to unset "abc.def" by passing key1 ?

Sergio Tulentsev · Accepted Answer · 2012-11-14 08:26:16Z

5

Yes, this is how json parser works. By the standard, hash keys must be enclosed in quotes, but some parsers are too forgiving and allow you to omit them. So, this is how mongo sees your code.

db.keyword.update({"state": "UT"}, {"$unset": {"key1": 1}});

You can get around this problem by constructing the hash manually. Something like this:

var key = 'def';
var key1 = 'abc.' + key;

var mod = {"$unset": {}};
mod["$unset"][key1] = 1;

db.keyword.update({"state": "UT"}, mod);

edited Nov 14, 2012 at 8:26

answered Nov 14, 2012 at 5:44

Sergio Tulentsev

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2 Comments

Raja Over a year ago

Tried it - It didnt work ... Somehow on the server side I see it still being passed as key1 only.

Raja Over a year ago

Thanks a lot for the prompt reply !!

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