Update #4
I have finally completed a fully functional app. In the firebase database, it consists of temperature and other attributes data from the window device. In the app, i have implemented patch and put to update data and get data. At the same time, together with a streambuilder widget which is an event listener to track any update on the database so it can update in real time.
This part of the app was the hardest as the database reference is always null when passed to other classes. Due to my changing the classes into different sections, it was a lot more confusing. I have also added functionality where it will wait till it gets a response from the window then it will update the page accordingly. The app is now ready to implement together with the window. The buttons are currently hardcoded.
Even though there are only 4 updates which seems less, but this app journey was insane. There were so much to do change, do and remove. I have earned knowledge about flutter (dart programming).