Question

Mongodb updates provide the $push modifier to append to an array. My problem is that i want this to happen on a dict e.g

If my record looks like this initially:

{"collaborations":{'id1':{'role':'dev','scope':'dev'}}}

I want to add another item(“id2” below) to the “collaborations” field dict to look something like this:

{"collaborations":{'id1':{'role':'dev','scope':'dev'},'id2':{'role':'qa','scope':'qa'}}}

I am trying with $push:

my_record.update({match_criteria},{$push,{"collaborations":{'id2':{'role':'qa','scope':'qa'}}}})

and also with $addToSet:

my_record.update({match_criteria},{$,{"collaborations":{'id2':{'role':'qa','scope':'qa'}}}})

With both of these, mongodb throws as error “Cannot apply $addToSet($push) modifier to non-array”.

How can this be done for dict types? Any ideas?

Answer 1

The problem is that $addToSet and $push modifiers work with arrays.

To update sub-document (that is what you need here) just use $set modifier with dot notation to access sub-document (field.subfield):

my_record.update({
    match_criteria
}, {
    '$set': {
        'collaborators.id2': {
            // new document fields here
        }
    }
})