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dart pub downgrade

Downgrade is one of the commands of the pub tool.

$ dart pub downgrade [--[no-]offline] [-n|--dry-run] [dependencies...] 

Without any additional arguments, dart pub downgrade gets the lowest versions of all the dependencies listed in the pubspec.yaml file in the current working directory, as well as their transitive dependencies. For example:

$ dart pub downgrade
Resolving dependencies... (1.2s)
+ barback 0.13.0
+ collection 0.9.1
+ path 1.2.0
+ source_maps 0.9.0
+ source_span 1.0.0
+ stack_trace 0.9.1
Changed 6 dependencies!

The dart pub downgrade command creates a lockfile. If one already exists, pub ignores that file and generates a new one from scratch, using the lowest versions of all dependencies.

See the dart pub get documentation for more information on package resolution and the system package cache.

Downgrading specific dependencies

It’s possible to tell dart pub downgrade to downgrade specific dependencies to the lowest version while leaving the rest of the dependencies alone as much as possible. For example:

$ dart pub downgrade test
Resolving dependencies...
  barback 0.15.2+2
  bot 0.27.0+2
  browser 0.10.0+2
  chrome 0.6.5
  collection 1.1.0
  path 1.3.0
  pool 1.0.1
  source_span 1.0.2
< stack_trace 0.9.2 (was 1.1.1)
  stagexl 0.10.2
< test 0.10.0 (was 0.11.4)
These packages are no longer being depended on:
- matcher 0.11.3
Changed 3 dependencies!

If you are downgrading a specific dependency, pub tries to find the highest versions of any transitive dependencies that fit the new dependency constraints. Any transitive dependencies are usually also downgraded as a result.

Getting a new dependency

If a dependency is added to the pubspec before dart pub downgrade is run, it gets the new dependency and any of its transitive dependencies, placing them in the .packages file. This is the same behavior as dart pub get.

Removing a dependency

If a dependency is removed from the pubspec before dart pub downgrade is run, it removes the dependency from the .packages file, thus making the dependency unavailable for importing. Any transitive dependencies of the removed dependency are also removed, as long as no remaining immediate dependencies also depend on them. This is the same behavior as dart pub get.

Downgrading while offline

If you don’t have network access, you can still run dart pub downgrade. Because pub downloads packages to a central cache shared by all packages on your system, it can often find previously downloaded packages without needing to use the network.

However, by default, dart pub downgrade tries to go online if you have any hosted dependencies. If you don’t want pub to do that, pass it the --offline flag. In offline mode, pub looks only in your local package cache, trying to find a set of versions that work with your package from what’s already available.

Options

For options that apply to all pub commands, see Global options.

--[no-]offline

By default, pub connects to the network to retrieve hosted packages (--no-offline). To use cached packages instead, use --offline. For details, see Getting while offline.

--dry-run or -n

Reports what dependencies would change but doesn’t change any.