Move ModalRoute.of(context) to access page args out of build()

[mrahimygk]

There are various situations that we need passed page arguments to call apis, but they need to move out of build(). initState() would be a good location for them.

[mrahimygk]

@march93

Seems I need to explain the problem better.
We are parsing args in build. this could result in calling our imperative line of code e.g. addCheckBox(); multiple times. To avoid this problem we used a global flag to check if the parsing is done already. But there can be a better way that considers the lifecycle of the view thus we can use that lifecycle function to init our NoteModel and do things like addCheckBox(); in thatLovelyMethod(context) and just draw the UI in build(). The didChangeDependencies() method has our desired context available but I know that it can be called multiple times in the lifecycle and I cannot fill my NoteModel/checkboxList there.

[march93]

@mrahimygk makes sense! Do you have any suggestions on the best lifecycle method to use? When args is in initState, build isn't able to find it as initState may not have completed yet. didChangeDependencies runs after initState completes but can't be used in this case

[mrahimygk]

I saw these 3 samples in stackoverflow:

Future.delayed(Duration.zero,() {
  parseArgs(context)
}

-=-=-=-=-=-

SchedulerBinding.instance.addPostFrameCallback((_) {
  parseArgs(context)
});

-=-=-=-=-

() async {
  await Future.delayed(Duration.zero);
  parseArgs(context)
}();

[hiashutoshsingh]

I have been using top 2 solutions for a while, it works like a charm.
Anything you want to do with context can be done with above approaches.

[march93]

@mrahimygk I just remembered another thing I used to do when initializing data. What do you think of args ??= ModalRoute.of(context).settings.arguments as AddNotePageArguments; initialized in didChangeDependencies? I tried the above examples but they don't work in initState as the context is not available when it's first called.

[mrahimygk]

We have to keep variables like hasAddedNewCheckboxAlready and they just will be moved to didChangeDependencies. So I presume this won't fix our main issue.

[hiashutoshsingh]

@mrahimygk I just remembered another thing I used to do when initializing data. What do you think of args ??= ModalRoute.of(context).settings.arguments as AddNotePageArguments; initialized in didChangeDependencies? I tried the above examples but they don't work in initState as the context is not available when it's first called.

did you user above methods like wrapping your function in delay ? I think it should work it works in my case.

[march93]

@hiashutoshsingh yea I wrapped it in delay, would you be able to share that part of the code?

[Trung15010802]

any update?