issues with consumers and providers - flutter

Question

Hello I am facing an issue with my flutter app using providers and consumer.
everything works fine how ever I have this issue in my debugger:
════════ Exception caught by foundation library ════════════════════════════════
The following assertion was thrown while dispatching notifications for CatergoryProvider:
setState() or markNeedsBuild() called during build.
This _InheritedProviderScope<CatergoryProvider> widget cannot be marked as needing to build because the framework is already in the process of building widgets. A widget can be marked as needing to be built during the build phase only if one of its ancestors is currently building. This exception is allowed because the framework builds parent widgets before children, which means a dirty descendant will always be built. Otherwise, the framework might not visit this widget during this build phase.
The widget on which setState() or markNeedsBuild() was called was: _InheritedProviderScope<CatergoryProvider>
value: Instance of 'CatergoryProvider'
listening to value
The widget which was currently being built when the offending call was made was: Consumer<CatergoryProvider>
dirty
dependencies: [_InheritedProviderScope<CatergoryProvider>]
When the exception was thrown, this was the stack
#0 Element.markNeedsBuild.<anonymous closure>
package:flutter/…/widgets/framework.dart:4138
#1 Element.markNeedsBuild
package:flutter/…/widgets/framework.dart:4153
#2 _InheritedProviderScopeElement.markNeedsNotifyDependents
package:provider/src/inherited_provider.dart:496
#3 ChangeNotifier.notifyListeners
package:flutter/…/foundation/change_notifier.dart:243
#4 CatergoryProvider.setLoading
package:quizz_app/provider/catergoryProvider.dart:43
...
The CatergoryProvider sending notification was: Instance of 'CatergoryProvider'
here is the consumer in question:
Consumer<CatergoryProvider>(
builder: (context, catergory, child) {
if (!catergory.isLoading() && !catergory.isList()) {
catergory.fetchCatergory();
}
catergories = catergory.getList();
return catergory.isLoading()
? ModalProgressHUD(
opacity: 0,
inAsyncCall: catergory.isLoading(),
child: Container())
: catergoryPage(catergories, context);
},
),
and this is where the stack trace leads me to:
void setLoading(value) {
loading = value;
notifyListeners();
}

Answer 1

It looks like you are probably calling setLoading(value) inside of a build method.. This would try to trigger a rebuild of the widget when notifyListeners() is invoked during the build of the widget.
Consider using a FutureBuilder or a StreamBuilder to change state depending when waiting on an async action.