Flutter 3.0 shows error : WidgetsBinding.instance!.addPostFrameCallback((_) => widget.onReady.call());

Question

flutter 3.0升级工程后出现如下错误

    Syncing files to device iPhone 13 Pro Max...
../../../Developer/flutter/.pub-cache/hosted/pub.dartlang.org/another_transformer_page_view-1.1.0/lib/src/another_transformer_page_view.dart:519:22: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Developer/flutter/packages/flutter/lib/src/widgets/binding.dart').
      WidgetsBinding.instance!.addPostFrameCallback(_onGetSize);
                     ^
../../../Developer/flutter/.pub-cache/hosted/pub.dartlang.org/another_transformer_page_view-1.1.0/lib/src/another_transformer_page_view.dart:537:22: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Developer/flutter/packages/flutter/lib/src/widgets/binding.dart').
      WidgetsBinding.instance!.addPostFrameCallback(_onGetSize);
                     ^
../../../Developer/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_login-3.2.0/lib/src/widgets/animated_text.dart:57:20: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Developer/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.addPostFrameCallback((_) {
                   ^
../../../Developer/flutter/.pub-cache/hosted/pub.dartlang.org/awesome_select-5.2.0/lib/src/widget.dart:1547:58: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Developer/flutter/packages/flutter/lib/src/widgets/binding.dart').
                MediaQueryData.fromWindow(WidgetsBinding.instance!.window);
                                                         ^
../../../Developer/flutter/.pub-cache/hosted/pub.dartlang.org/awesome_select-5.2.0/lib/src/text_error.dart:99:20: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Developer/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.addPostFrameCallback((_) {

这是 flutter 的 bug？任何人都可以将此报告给 flutter。我不知道如何将此报告给 flutter 团队。

This Warning bug is resolved. see my comment in correct answer I have written ( if you are a mac user goto finder -> press goto button by swift+cmd+G -> past all 6 files I have mentioned or you find an error and replace [root-name] with your root directory name.

Answer 1

这是你在项目中使用的库的错误，别担心。它将在 lib

的下一个版本依赖项中修复

或者你可以从 lib 中 fork 代码，修复它，然后创建一个 pull request 到 main

example of this issue

使用

cached_network_image:
    git:
      url: https://github.com/XuannThucc/flutter_cached_network_image.git
      path: cached_network_image
      ref: ff72f00f142f13d889d7549e013af91cb0b523ab

而不是

cached_network_image: ^3.2.0

或等待更新cached_network_image: ^3.2.1

Answer 2

'WidgetsBinding.instance' getter 曾经是可空类型。在新的更新中，它被更改为 Non-nullable。因此，现在旧包在更新后会显示此信息，因为它们在那里使用了 null 感知运算符。它将在新版本中修复。现在，您只需从日志中显示的行中删除空感知运算符，重建后将不会再有警告。

Flutter 3.0 shows error : WidgetsBinding.instance!.addPostFrameCallback((_) => widget.onReady.call());

Flutter 3.0 shows error : WidgetsBinding.instance!.addPostFrameCallback((_) => widget.onReady.call());

upgrade

dart

flutter

flutter-3.0