Uniform useField and mobx keystone

[webberwang]

• If we assign a model toJson to model, the mobx is controlling the data
• Any changes from from UI won't be reflected
• If we use getSnapshot it doesn't work either, since the data is immutable
• If we use toJS it works, since it just removes observability
• Actually both not true, it's because toJS creates an object without childMapperComponent, resulting in initialValue in useField. If we pass a null component, the id won't even set since it doesn't match the shape
• If we use useField, we'll need the parent as name, not the id, since we'll need to go one level up to deal with undefined values

---

• Custom field docs show in schema uniforms component and also as as pre-defined field directly in the form
• useField and connectField both work, but maybe connectField is more encapsulated
• connectField requires name, and scopes everything to that name, good for nested id
• Also can use leaf to remove nesting

---

• model data are not cleaned during submit, extra fields will show up even if it's not in schema or fields