Bloc: Question regarding waiting for a specific State

[TheMeanCanEHdian]

I've found myself at a dead end with some functionality I am trying to write and I am hoping for some assistance. The code itself is rather cumbersome so I'm going to do my best to summarize the idea of what I am trying to accomplish and provide a rough example.

Please let me know if there are things I can do to make it easier to help.

Problem:
I have 4 states: Initial, InProgress, Success, and Failure.
One of my widgets (flutter_slidable) has a parameter that requires me to return a true or false value and if it receives a null value it acts like it received false.
All of this code is nested inside of a BlocConsumer.
If I simply do an if statements waiting for Success or Failure it will instead return null because the state first moves to InProgress, and then when it finally switches to Success/Failure the widget no longer cares and has moved on with the null value as a result of the InProgress state.

Question:
Is there a way that I can await for a _specific_ state rather than taking an action based on each state?

Preemptive thanks to anyone who can help!

What I have:

Widget(
     onWillDismiss: (actionType) {
          if (state is Success) {
               return true;
          }
          if (state is Failure) {
               return false;
          }
          state is actually InProgress so it ends up as null
     }
)

An idea of what I want:

Widget(
     onWillDismiss: (actionType) {
          [wait for or loop until state is Success/Failure] {
               if (state is Success) {
                    return true;
               }
               if (state is Failure) {
                    return false;
               }
          }
     }
)

[felangel]

Hi @TheMeanCanEHdian 👋
Thanks for opening an issue!

Are you able to make a sample project which illustrates the issue and share the link? Thanks 👍

[TheMeanCanEHdian]

Yes, I had a busy day so I didn't get to this but I will get you a small "working" example. Thanks!

[TheMeanCanEHdian]

Hey @felangel

So by breaking this down into a smaller working example I appear to have run into a more root problem with my Bloc state management before I even got to the function I described above. So first a thank you for making me break this down into basics so I can start with the right questions.

Do let me know if I should spin this into another issue as it is unclear at this time if the title will still be relevant.

Here is a link to a repository containing the lib folder and pubspec.yaml for running this code.

Summary:
I have 2 Blocs in this example code; one (ListBloc) that would be for fetching a list of items from a server and one (RemoveBloc) that would be for removing individual items from the server. The UI acts as a way to see these items and initiate a removal.

I have elements of the UI that I want to react to the current ListBloc as well as the RemovalBloc. Mainly a few CircularProgressIndicators and also the ability to cancel the dismissal if the Removal fails (This is what my initial question revolved around but I commented the code out at this time for reasons below).

Issue:
It appears that the earliest issue I run into when I am nesting bloc builders in order to try and have access to each of their states to take the above-mentioned actions.

I'm confident that at least one of my issues is with how I am using these BlocBuilders. When either the line 56 of slidable_card.dart is commented out or I remove the nested RemoveBloc BlocBuilder all together the dismissal animates as expected. If both those items are present then it fails to do so.

Please let me know if I can offer more information. I have attempted to comment my code as effectively as possible to help.

[Jomik]

It looks to me like you are using the Bloc synchronously.
You expect that the bloc state has been updated before onWillDismiss is called, that is unlikely, in my opinion.
I would probably use a BlocListener and then dismiss or not according to RemoveSuccess and RemoveFailure there.
Does that make sense and achieve what you need?

[felangel]

Closing for now but feel free to comment with additional questions and I'm happy to continue the conversation 👍
Thanks @Jomik for taking the time to answer, I really appreciate it 🙏

[TheMeanCanEHdian]

Thank you for your reply, the concept of using the BlocListener makes sense to me. I eventually found out that of one the primary issues I was having was a result of the widget being nested in a BlocBuilder for RemoveBloc causing it to rebuild when I would try and remove.

Hopefully, this all carries over to my actual application.

Thank you.