Think about existing-model-in-store handling

[SpaceK33z]

In Backbone, when you do this:

const model = new Backbone.Model();
const collection = new Backbone.Collection.extend({ model: model });

collection.add({ id: 1, foo: false });
// do some other stuff
collection.add({ id: 1, foo: true });

// Final result: [{ id: 1, foo: true }]

It will only add a model to the collection once and override its values. Currently mobx-binder will not do that, it would just add the same model twice.

I'm not sure yet if we should build this into mobx-binder. It can be very nice, but it can also be weird black magic.

Maybe specifically for .add() it make sense, but for .fetch() I'd rather do a full reset of the store each time. In most of our Backbone apps we now do collection.fetch({ reset: true }) nearly everywhere, so we could make that the default here.

Needs discussion with @jasperstam and @abzainuddin.

[SpaceK33z]

Discussed this with Burhan, we should throw an error if .add() tries to add a model to the store that already exists with that id.