[Solved] Flutter format document not working

I have been using Android Studio for Flutter project. Some of my friends suggested me to give a try to Visual Studio Code as well. I like Visual Studio Code for javascript, typescript and ReactJS projects. So, thought of giving it a try. So, I followed Get Started from official docs. After sometime, I found out that my flutter code format were not working as expected. I started getting error as “Extension ‘Flutter’ cannot format ‘lib/body.dart'” here ‘lib/body.dart’ is file that I was trying to format. My initial thought was perhaps it could have happened due to syntax errors. But, I couldn’t see any error in visual studio code. See the screenshot below for the source code of ‘body.dart’. Look at Editor status bar for format error.

But, I was able to format it using flutter format command. So, I was sure that it could be editor settings that could have caused it. So, I looked at editor settings again (settings.json). My dart format configuration is as below.

"[dart]": {
  "editor.defaultFormatter": "Dart-Code.flutter",
  "editor.formatOnSave": true
},

No error on this configuration, right!. Well, this seems to be the actual problem. I am going to borrow statement from github issue comment from https://github.com/Dart-Code/Dart-Code/issues/1274#issuecomment-587549984 “The dart formatter is in the Dart extension (Dart-Code.dart-code) rather than the Flutter one”. So, there are two solutions for this problem.

1. Disable [dart] formatter that was added to settings.json
2. Use proper dart formatter “Dart-code.dart-code”

I opted to use “Dart-code.dart-code” as it allows us to have more control over format configurations. My configuration after changing to right dart formatter.

  "[dart]": {
    "editor.defaultFormatter": "Dart-Code.dart-code",
    "editor.formatOnSave": true
  },

Now, whenever I save my dart file, it also gets formatted nicely. I hope this helps you to solve your formatting issue as well.

Resources that were helpful to debug this problem.

https://github.com/Dart-Code/Dart-Code/issues/1274#issuecomment-587549984