Error: The method 'ancestorStateOfType' isn't defined for the class 'BuildContext'

Question

When using the class Bloc provider as follows, I get the error:

'The method 'ancestorInheritedElementForWidgetOfExactType' isn't defined for the type 'BuildContext'.'

So I replaced this line context.ancestorInheritedElementForWidgetOfExactType(type)?.widget;

with this line context.getElementForInheritedWidgetOfExactType<_BlocProviderInherited<T>>().widget;

but then I get the following Error:

Error output from Xcode build:
↳
** BUILD FAILED **

Xcode's output:
↳
../../../development/flutter/.pub-cache/hosted/pub.dartlang.org/dynamic_theme-1.0.1/lib/dynamic_theme.dart:25:20: Error: The method 'ancestorStateOfType' isn't defined for the class 'BuildContext'.
 - 'BuildContext' is from 'package:flutter/src/widgets/framework.dart' ('../../../development/flutter/packages/flutter/lib/src/widgets/framework.dart').
Try correcting the name to the name of an existing method, or defining a method named 'ancestorStateOfType'.
    return context.ancestorStateOfType(const TypeMatcher<DynamicThemeState>());
                   ^^^^^^^^^^^^^^^^^^^

Command PhaseScriptExecution failed with a nonzero exit code
note: Using new build system
note: Building targets in parallel
note: Planning build
note: Constructing build description

Could not build the precompiled application for the device.

Error launching application on iPhone 

This is the Bloc Provider i am using:

class BlocProvider<T extends BlocBase> extends StatefulWidget {
   BlocProvider({
   Key key,
   @required this.child,
   @required this.bloc,}) : super(key: key);
   final Widget child;
   final T bloc;
   @override
   _BlocProviderState<T> createState() => _BlocProviderState<T>();

   static T of<T extends BlocBase>(BuildContext context) {
   final type = _typeOf<_BlocProviderInherited<T>>();
   _BlocProviderInherited<T> provider =
   context.ancestorInheritedElementForWidgetOfExactType(type)?.widget;
   return provider?.bloc;
  }
}

I am on the Master channel, Flutter (Channel master, 1.26.0-2.0.pre.275)

Answer 1

after upgrade dev channel was almost the same issue

.pub-cache/hosted/pub.dartlang.org/dynamic_theme-1.0.1/lib/dynamic_theme.dart:25:20: Error: The method 'ancestorStateOfType' isn't defined for the class 'BuildContext'.
'BuildContext' is from 'package:flutter/src/widgets/framework.dart' ('/home/liudmila/snap/flutter/common/flutter/packages/flutter/lib/src/widgets/framework.dart').
Try correcting the name to the name of an existing method, or defining a method named 'ancestorStateOfType'.

with block 4.0.0

just change this in file .pub-cache/../dynamic_theme.dart:25:20

context.ancestorStateOfType()

on that

context.findAncestorStateOfType<DynamicThemeState>();

thats temp solution, but app is work

Answer 2

You are using an old version of flutter_bloc, first you should upgrade it.

But, in fact the real problem is that context.ancestorInheritedElementForWidgetOfExactType(type) is deprecated in favor of context.getElementForInheritedWidgetOfExactType<T>() but still available in the stable channel, but in master is already removed.

Then it is necessary to update your code because Bloc has suffered breaking changes.

UPDATE: The mentioned change is already in the stable channel.

Answer 3

try changing the packages version in pubspec.yaml it worked for me i changed provider version to 5.0.0 , then it started working