Get is one of the commands of the pub tool.
$ dart pub get [--offline]This command gets all the dependencies listed in the
pubspec.yaml file in the current working
directory, as well as their
transitive dependencies.
For example:
$ dart pub get
Resolving dependencies...
Got dependencies!
If the system cache
doesn’t already contain the dependencies, dart pub get
updates the cache,
downloading dependencies if necessary.
To map packages back to the system cache,
this command creates a .packages file.
Once the dependencies are acquired, they may be referenced in Dart code.
For example, if a package depends on test:
import 'package:test/test.dart';When dart pub get gets new dependencies, it writes a
lockfile to ensure that future
gets will use the same versions of those dependencies.
Application packages should check in the lockfile to source control;
this ensures the application will use the exact same versions
of all dependencies for all developers and when deployed to production.
Library packages should not check in the lockfile, though, since they’re
expected to work with a range of dependency versions.
If a lockfile already exists, dart pub get uses the versions of dependencies
locked in it if possible. If a dependency isn’t locked, pub gets the
latest version of that dependency that satisfies all the version
constraints.
This is the primary difference between dart pub get and
dart pub upgrade, which always tries to
get the latest versions of all dependencies.
Package resolution
By default, pub creates a .packages file
that maps from package names to location URIs.
Before the .packages file, pub used to create packages directories.
For more information, see the package specification file proposal.
Getting a new dependency
If a dependency is added to the pubspec and then dart pub get is run,
it gets the new dependency and any of its transitive dependencies and
updates the mapping in the .packages file.
However, pub won’t change the versions of any already-acquired
dependencies unless that’s necessary to get the new dependency.
Removing a dependency
If a dependency is removed from the pubspec and then dart pub get is run,
it removes the dependency from the .packages file,
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.
Removing a dependency never changes the versions of any
already-acquired dependencies.
The system package cache
Dependencies downloaded over the internet, such as those from Git and the pub.dev site, are stored in a system-wide cache. This means that if multiple packages use the same version of the same dependency, it only needs to be downloaded and stored locally once.
By default, the system package cache is located in the .pub-cache
subdirectory of your home directory (on Mac and Linux),
or in %LOCALAPPDATA%\Pub\Cache (on Windows;
the location might vary depending on the Windows version).
You can configure the location of the cache by setting the
PUB_CACHE
environment variable before running pub.
Getting while offline
If you don’t have network access, you can still run dart pub get.
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 get tries to go online if you
have any hosted dependencies,
so that pub can detect newer versions of 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.
Keep in mind that pub generates a lockfile. If the
only version of some dependency in your cache happens to be old,
offline dart pub get locks your app to that old version.
The next time you are online, you will likely want to
run dart pub upgrade to upgrade to a later version.
Options
The dart pub get command supports the --offline
command-line argument, as mentioned above.
For options that apply to all pub commands, see Global options.