Apply updates alternative

[rjwats]

No description provided.

[rjwats]

Thinking of removing JsonSerializer/JsonDeserializer and replacing them with the following signatures in StatefulService.h:

enum class StateUpdateResult { 
  CHANGED = 0, // The update changed the state and propagation should take place if required
  UNCHANGED, // The state was unchanged, propagation should not take place
  ERROR // There was a problem updating the state, propagation should not take place
};

template <class T>
using StateUpdater = StateUpdateResult (*)(T& settings);
template <class T>
using JsonStateUpdater = StateUpdateResult (*)(JsonObject& root, T& settings);

template <class T>
using StateReader = void (*)(const T& settings);
template <class T>
using JsonStateReader = void (*)(T& settings, JsonObject& root);

[kasedy]

How about to extend the example with a brightness param. It is a good use case to show how to make validation. Slider can go from 0 to 10 with 10% brightness change per snap. Update function will validate that is brightness in a given range and map it into analogWrite range from 0 to PWMRANGE (1023) with map function. I would also keep on-off switch.

[rjwats]

Maybe let's address the larger change first.

[kasedy]

I have an idea with auto-transaction. I'll prepare a PR into this branch to show my findings.

[kasedy]

I'll do it later as a separate PR.

[rjwats]

I will sort out updating the docs tomorrow.

[rjwats]

Docs updated, how are we looking?

[kasedy]

Suggested change

	```cpp
	lightStateService.update([&](LightState& state) {
	state.on = true; // turn on the lights!
	return StateUpdateResult::CHANGED; // notify StatefulService of the change
	}, "timer");
	```
	```cpp
	lightStateService.update([&](LightState& state) {
	if (state.on) {
	return StateUpdateResult::UNCHANGED;
	}
	state.on = true; // turn on the lights!
	return StateUpdateResult::CHANGED; // notify StatefulService of the change
	}, "timer");

[kasedy]

Suggested change

	beginTransaction();
	StateUpdateResult result = stateUpdater(jsonObject, _state);
	if (result == StateUpdateResult::CHANGED) {
	callUpdateHandlers(originId);
	}
	endTransaction();
	return result;
	beginTransaction();
	StateUpdateResult result = stateUpdater(jsonObject, _state);
	endTransaction();
	if (result == StateUpdateResult::CHANGED) {
	callUpdateHandlers(originId);
	}
	return result;

We can close transaction much earlier, right after state changed.

[kasedy]

Suggested change

	StateUpdateResult update(std::function<StateUpdateResult(T&)> stateUpdater, const String& originId) {
	beginTransaction();
	StateUpdateResult result = stateUpdater(_state);
	if (result == StateUpdateResult::CHANGED) {
	callUpdateHandlers(originId);
	}
	endTransaction();
	return result;
	}
	StateUpdateResult update(std::function<StateUpdateResult(T&)> stateUpdater, const String& originId) {
	beginTransaction();
	StateUpdateResult result = stateUpdater(_state);
	endTransaction();
	if (result == StateUpdateResult::CHANGED) {
	callUpdateHandlers(originId);
	}
	return result;
	}

[rjwats]

Thanks for the changes @kasedy - I'll get these changes made and merged into master after work today.

My plan is to then update and re-open your access point fixes PR - also fixing the other bugs I've spotted.

[kasedy]

LGTM