SharedPreferencesMigration
public final class SharedPreferencesMigration<T extends Object> implements DataMigration
DataMigration instance for migrating from SharedPreferences to DataStore.
Summary
Public constructors |
|---|
<T extends Object> SharedPreferencesMigration(DataMigration from SharedPreferences to DataStore. |
<T extends Object> SharedPreferencesMigration(DataMigration from SharedPreferences to DataStore. |
Public methods |
|
|---|---|
void |
cleanUp()Clean up any old state/data that was migrated into the DataStore. |
@NonNull T |
Perform the migration. |
boolean |
shouldMigrate(@NonNull T currentData)Return whether this migration needs to be performed. |
Public constructors
SharedPreferencesMigration
public <T extends Object> SharedPreferencesMigration(
@NonNull Function0<@NonNull SharedPreferences> produceSharedPreferences,
@NonNull Set<@NonNull String> keysToMigrate,
@NonNull SuspendFunction1<@NonNull T, @NonNull Boolean> shouldRunMigration,
@NonNull SuspendFunction2<@NonNull SharedPreferencesView, @NonNull T, @NonNull T> migrate
)
DataMigration from SharedPreferences to DataStore.
Note: This migration only supports the basic SharedPreferences types: boolean, float, int, long, string and string set. If the result of getAll contains other types, they will be ignored.
Example usage:
val sharedPrefsMigration = SharedPreferencesMigration(
produceSharedPreferences = { EncryptedSharedPreferences.create(...) }
) { prefs: SharedPreferencesView, myData: MyData ->
myData.toBuilder().setCounter(prefs.getCounter(COUNTER_KEY, default = 0)).build()
}
| Parameters | |
|---|---|
@NonNull Function0<@NonNull SharedPreferences> produceSharedPreferences |
Should return the instance of SharedPreferences to migrate from. |
@NonNull Set<@NonNull String> keysToMigrate |
The list of keys to migrate. The keys will be mapped to datastore .Preferences with their same values. If the key is already present in the new Preferences, the key will not be migrated again. If the key is not present in the SharedPreferences it will not be migrated. If keysToMigrate is not set, all keys will be migrated from the existing SharedPreferences. |
@NonNull SuspendFunction1<@NonNull T, @NonNull Boolean> shouldRunMigration |
A lambda which accepts current data of type |
@NonNull SuspendFunction2<@NonNull SharedPreferencesView, @NonNull T, @NonNull T> migrate |
maps SharedPreferences into T. Implementations should be idempotent since this may be called multiple times. See |
SharedPreferencesMigration
public <T extends Object> SharedPreferencesMigration(
@NonNull Context context,
@NonNull String sharedPreferencesName,
@NonNull Set<@NonNull String> keysToMigrate,
@NonNull SuspendFunction1<@NonNull T, @NonNull Boolean> shouldRunMigration,
@NonNull SuspendFunction2<@NonNull SharedPreferencesView, @NonNull T, @NonNull T> migrate
)
DataMigration from SharedPreferences to DataStore.
If the SharedPreferences is empty once the migration completes, this migration will attempt to delete it.
Example usage:
val sharedPrefsMigration = SharedPreferencesMigration(
context,
mySharedPreferencesName
) { prefs: SharedPreferencesView, myData: MyData ->
myData.toBuilder().setCounter(prefs.getCounter(COUNTER_KEY, default = 0)).build()
}
| Parameters | |
|---|---|
@NonNull Context context |
Context used for getting SharedPreferences. |
@NonNull String sharedPreferencesName |
The name of the SharedPreferences. |
@NonNull Set<@NonNull String> keysToMigrate |
The list of keys to migrate. The keys will be mapped to datastore .Preferences with their same values. If the key is already present in the new Preferences, the key will not be migrated again. If the key is not present in the SharedPreferences it will not be migrated. If keysToMigrate is not set, all keys will be migrated from the existing SharedPreferences. |
@NonNull SuspendFunction1<@NonNull T, @NonNull Boolean> shouldRunMigration |
A lambda which accepts current data of type |
@NonNull SuspendFunction2<@NonNull SharedPreferencesView, @NonNull T, @NonNull T> migrate |
maps SharedPreferences into T. Implementations should be idempotent since this may be called multiple times. See |
Public methods
cleanUp
public void cleanUp()
Clean up any old state/data that was migrated into the DataStore. This will not be called if the migration fails. If cleanUp throws an exception, the exception will be propagated back to the DataStore call that triggered the migration and future calls to DataStore will result in DataMigrations being attempted again. This method may be run multiple times when any failure is encountered.
This is useful for cleaning up files or data outside of DataStore and accessing any data from DataStore directly from inside this function will result in deadlock, since DataStore doesn't return data until all migrations complete.
migrate
public @NonNull T migrate(@NonNull T currentData)
Perform the migration. Implementations should be idempotent since this may be called multiple times. If migrate fails, DataStore will not commit any data to disk, cleanUp will not be called, and the exception will be propagated back to the DataStore call that triggered the migration. Future calls to DataStore will result in DataMigrations being attempted again. This method may be run multiple times when any failure is encountered.
Note that this will always be called before a call to cleanUp.
Note that accessing any data from DataStore directly from inside this function will result in deadlock, since DataStore doesn't return data until all migrations complete.
| Parameters | |
|---|---|
@NonNull T currentData |
the current data (it might be populated from other migrations or from manual changes before this migration was added to the app) |
| Returns | |
|---|---|
@NonNull T |
The migrated data. |
shouldMigrate
public boolean shouldMigrate(@NonNull T currentData)
Return whether this migration needs to be performed. If this returns false, no migration or cleanup will occur. Apps should do the cheapest possible check to determine if this migration should run, since this will be called every time the DataStore is initialized. This method may be run multiple times when any failure is encountered.
Note that this will always be called before each call to migrate.
Note that accessing any data from DataStore directly from inside this function will result in deadlock, since DataStore doesn't return data until all migrations complete.
| Parameters | |
|---|---|
@NonNull T currentData |
the current data (which might already be populated from previous runs of this or other migrations) |