$inc - default value (if not exists)

[Alexander Kit]

When we increment the value of the property, which not exists, mongo sets its initial value to zero and then performs the incrementation. Is it possible to define this `initial value`? 

My use case: There are dynamic properties, which can't be preinitialised/created on the first insert, but they all have the default start value: 100. So I would like to get this: 

{ $inc: { "en.points" : 5 } } 

to insert (if not exists): 105. 

I would also like to eliminate additional requests to the DB, to check if any value for the property exists.

Would anybody have some thoughts on this?

Thanks in advance,

Alex

[Alexander Kit]

UPD. As for now, before incrementing I do one additional request:

db.users.update({
    '_id': ObjectId('id'),
    'en.points': { $exists: false }
}, {
    $set: { 
        'en': {
            points: 100,
            // ... other
        }
})