What I do is fetching items from Firebase then saving them in a list and then I display them in a ListView. The Problem that I have now is that I check if the list has Items and if so it displays my ListView with the Items and if there are no items it displays a Text but even but even if there are items the text gets displayed but after pressing hot reload the items get shown.
My guess was that there is a Problem with the State of the Widgets overall because stuff like SetState has no effect or a Refresh Indicator
Is there a reason why the StreamBuilder is following your masterListStart().asStream as opposed to the masterList stream? I'm not saying it's wrong, its just not immediately obvious.
Either way, it's not rebuilding automatically because the only part of your displayStory method that is reactive to the stream doesn't get built until after the non empty list condition is met. Without implementing a reactive state management solution there's nothing in your code that automatically notifies any listeners that the state of the storysList has changed, which means nothing is triggering a rebuild. Which is why you have to hot reload to see the changes.
Without me getting too deep into your code, try returning the StreamBuilder at the top level of the displayStory method and putting all the conditionals inside its its builder method.
Related
I am successfully able to call the API function during pull to refresh action.
I also understand the insertitem and removeitem function on AnimatedList using global key
but I am having a hard time looking for references wherein the refresh indicator and animated list are combined.
If you could share a clue on what to use for the AnimatedList so that it gets updated or rebuild the list, that would be enough for me to handle the rest.
How can it update a list view elements without doing pull-to-refresh
If I'm adding an element in a dialog window or from an Api, how to add/update the list view elements automatically.
Should I use StreamBuilder?
Use state management pub like Getx, or something with adlistener.
Yes you can use stream builder and you can also use setstate
setState(() { });
StreamBuilder Widget builds itself based on the latest snapshot of interaction with a Stream. Thus the state of the app changes whenever new elements are added in the list as long as the connection status is active.
You can also use the combination of ListView Builder and setState method, though the state of the app needs to change whenever a new element is added. Earlier StreamBuilder widget was updating the state of the app. Various methods like adding a button to the screen, which can help the user manually change the state; can be used depending on the use case.
You can read more about it from the official docs: setState method
StreamBuilder
This answer is not exactly about updating listView, but updating a widget(PiChart). As listview is also a widget, the implementation will be the same to update without refreshing.
In this method, I am using streamBuilder to update the widget. so need not refresh the app to update the data.
https://stackoverflow.com/a/69800324/13577765
Let me start by explaining the problem. I have several buttons which are created based on data I'm getting from a server. On each button click I need to create and display a widget which will present me some data (this widget is also built dynamically). The state of this widget has to be preserved during the lifetime of the app. (for example if I click another button and show a different widget, I need to be able to click on the first button and show the first widget in its preserved state). Number of buttons can also be changed during the app lifetime.
I tried using IndexedStack to achieve this, but when the number of buttons is changed I need to add "pages" to IndexedStack, therefore I need to recreate a new IndexedStack which will have some of my old widgets, so I pull widgets from a List or create new ones if needed. This works great, except Flutter calls dispose() method on my widgets which are stored in the list. I tried using the AutomaticKeepAliveClientMixIn but it didn't help.
I'm guessing this has something to do that the widgets get detached from the parent, but when I reattach them to new parent (new Indexed stack) Flutter doesn't figure out this properly.
Any ideas?
Try to store data to local storage or sqlite for persistence data.
Say I have a Flutter app with two screens - screen A and screen B. Screen A is just a ListView that displays a list of items but needs to perform a network call whenever the list changes and then update the list. Screen B can modify the list of items but I want screen A to only perform the network call when screen A is in the foreground and being displayed. As far as I can tell, I cannot do this easily. Screen A is not disposed and reinitialized when navigating to and from screen B. It would very helpful if StatefulWidget had onForeground and onBackground methods to override, but they do not. This problem is not exclusive to navigation either, but this same problem presents itself when using PageView with full-screen pages. Is there some proper/standard way of implementing this?
My current setup is as follows: I let the parent widget to both screen A and B hold the list in a ValueNotifier and pass it to both screens when constructing them. Then, screen A listens for changes on the ValueNotifier and performs a network call whenever it does. So, in order to determine whether screen A is in the foreground/background, I will have to start/stop listening for changes before/after navigating. But I haven't started implementing this, as I think it will get complicated when widgets far down the widget tree trigger the navigation or other widgets need to know whether they're in the foreground/background.
Another option I've thought of is instead of observing for changes in the list, I could rather just return a result from screen B saying whether or not the list changed and react then. But I can think of many ways this can complicate my code as well since my real app involves more than just one dependency. I would have to create a custom result class for each screen containing a record of all the data that changed then it would be tedious if I want to add more data in the future. And how would I handle navigation to screen B then screen C? The result would have to be retained and passed down so screen A can react to changes made by screen C. I would also have to ensure all calls to Navigator.pop contained the result, and override back button presses to pop with the result. And I'd also have to ensure that the result makes it to the proper widgets that need to react to changes.
Am I just missing something simple to accomplish this? I am not the most experienced with Flutter and I wouldn't be surprised if there's some easy solution I haven't learned yet.
Edit: After some more testing, it appears AnimationController does something similar to what I need with the vsync parameter, in that it does not update when the State is in the background or when it is not being drawn. So, I could use SingleTickerProviderStateMixin on screen A's state, then use createTicker to create a Ticker, and then check if the Ticker.isTicking whenever the list changes. If it is ticking, screen A is in the foreground, otherwise it is in the background. Although I'm not sure if this is a good approach, since it appears Ticker's are really only used for Animations and there's nothing documented for a use case like mine.
When the user logs in, they get pushed to the homepage and their data is retrieved from database on initstate and then the widgets are built. However, i noticed for the widgets that are built without a streambuilder, where i manually retrieve data once, are duplicated if i navigate to another page and then come back. When I say duplicated I mean the exact same data is redundantly copied again using the same widget, so like a users' profile pic could show up twice. I am using a listview most of the time for these cases/
How do i avoid this and just built the widgets once so if the user goes back the page stays the same?