How to migrate code to null safety in Dart

flutter dart migrate code-migration dart-null-safety
Paresh Mangukiya picture Paresh Mangukiya · Mar 16, 2021 · Viewed 14.5k times · Source

Recently Flutter team announced the Dart language now supports sound null safety! and is available in Dart 2.12 and Flutter 2. I want to migrate the app code to null safety.

How to migrate my packages to null safety,

It would be great if someone could give instructions about migrating to null-safety.

Answer

Javeed Ishaq picture Javeed Ishaq · Aug 16, 2021

  1. Run flutter upgrade in the terminal to upgrade Flutter

  2. Run dart migrate to run the dart migration tool

  3. Solve all errors which the migration tool shows

  4. Run flutter pub outdated --mode=null-safety to print all outdated packages

    enter image description here

You can see if the packages you depend upon support null-safety.

  1. Run flutter pub upgrade --null-safety to upgrade all packages automatically
  2. Check the code for errors and solve them
  3. Run dart migrate again and it should now be successful. Follow the link to check out the proposed changes
  4. Press the "Apply Migration" button
  5. Check the code for errors again and fix them

Congratulations, when finished you should now be able to run the app with sound null-safety.

Run flutter run in the command line and the application should run with the command line displaying:

enter image description here

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