Update a value in MongoDB based on its current value

Question

I want to do something like this, but the this keyword doesn't seem to be set inside the update statement.

db.items.update({foo:…}, {$set: {bar: this.foo}}, false, true)

Do I have to use eval to accomplish this?

There is a feature request for this: jira.mongodb.org/browse/SERVER-458 — Thilo
– Thilo, Commented Sep 15, 2011 at 7:31
Possible duplicate of Update MongoDB field using value of another field — Xavier Guihot
– Xavier Guihot, Commented Jun 11, 2019 at 21:20

kristina · Accepted Answer · 2010-03-19 20:12:56Z

5

Yes, you can't refer to other fields in the modifier. You'll have to use db.eval.

answered Mar 19, 2010 at 20:12

kristina

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