MobX State Tree - exporting the model validation?

Question

Is there a recommended way to export the model and use it as validation in a server side request?

i.e If I have a user

User = types.model("User", {
    id: types.identifier(),
    firstName: types.string,
    lastName: types.string,
    leftHanded: types.optional(types.boolean, false),
  })

And then an express endpoint

app.put('/user', function(req, res) {
  const user = User.create(req.body);
  const record = db.push(getSnapshot(user)).write();
  res.send(record);
});

If the server is bundled with the app then everything is fine but what if I want to decouple them and make a standalone API server ?

Does it make sense to have the domain models as a separate package?

(would love to add mobx-state-tree tag but I don't have rep)

Answer 1

Yes it make sense to have separate module for domain. You even can move all domain logic there. And if domain is large and app is complex this module can be even developed separately by somebody else.
For complex systems separate package is good choose. Disadvantage of this you will have models inside node_modules directory. This is not very convenient. I prefer to have it inside src/ to simplify modification.
Another way to use same part of code in several projects is git submodules and git subtree (better).