/Jetpack-Navigation-Fragment-NavGraph-Dagger-SavedStateHandle-FTUE-Experiment

[DEMO] Sample code to display a combination of Jetpack-Navigation, Fragment, NavGraphs, Dagger, SavedStateHandle, AssistedInject, and EventEmitter - based on the FTUE example code in simple-stack-tutorials, but originally described by Google.

Primary LanguageKotlin

Jetpack Navigation + Fragments + NavGraphs + SavedStateHandle + Dagger + AssistedInject + EventEmitter (toasts / navigation commands)

This is a sample repository for the aforementioned tools (primarily Jetpack Navigation + NavGraph-scoped ViewModel + SavedStateHandle + Dagger + AssistedInject).

The sample is based on the FTUE-rewrite in Simple-Stack Tutorial: First-Time User Experience with RxJava.

. . .

The original version of the "FTUE sample" is based on the "Conditional Navigation" section of Jetpack Navigation documentation.

Please beware that the original FTUE sample has various anti-patterns that are fixed in this sample:

  • Jetpack Navigation docs uses by activityViewModels() instead of properly scoping the ViewModel to the NavBackStackEntry of the registration_graph

  • Jetpack Navigation docs does NOT care about process death at all, while this sample uses the lifecycle-viewmodel-savedstate artifact and SavedStateHandle to properly survive across process death

  • Jetpack Navigation docs claim you must have the startDestination on your graph at all times, in this sample we can clearly see a "splash" to make conditional navigation based on auth state.

  • In general, Google samples rely on LiveData<Event<T>> (which should be considered an anti-pattern) and delegate Navigation responsibilities to the Fragment, in this sample we rely on EventEmitter to invoke NavController methods from the ViewModel directly.

License

Copyright 2020 Gabor Varadi

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.