Use prefixed internal properties to allow more freedom for schema path names

[adamreisnz]

This is likely going to be something for a next major release, but I'd like to see the limitations that are currently in place for restricted schema path names lifted, by using internal properties which are prefixed with _ or $ or anything else, so that users are free to use any non-prefixed path name they like.

I've run into this limitation twice now, where I wanted to have isNew and collection as my document properties. (It's surprisingly hard to find a synonym for isNew that is as concise and to the point.)

So I'm throwing it up here for discussion, what do you think?

[vkarpov15]

Yeah that's definitely something I want to see, isNew -> $isNew and save -> $save because mongodb doesn't let you save keys that start with $ anyway.

[adamreisnz]

If it'll take a while for this to be released, could Mongoose issue a warning when "reserved" property names are detected in a schema?

[vkarpov15]

It already does, mongoose throws an error if you try to use reserved property names like 'set'. If mongoose doesn't throw an error in that case, please let me know what property name you're getting an error with and we'll fix it.

[adamreisnz]

Sorry, it was my own fail in the end, which I mistakenly took for a reserved schema name error 🤦‍♂️