DataStoreDelegateKt

public final class DataStoreDelegateKt


Summary

Public methods

static final @NonNull ReadOnlyProperty<@NonNull Context, @NonNull DataStore<@NonNull T>>
<T extends Object> dataStore(
    @NonNull String fileName,
    @NonNull Serializer<@NonNull T> serializer,
    @Nullable ReplaceFileCorruptionHandler<@NonNull T> corruptionHandler,
    @NonNull Function1<@NonNull Context, @NonNull List<@NonNull DataMigration<@NonNull T>>> produceMigrations,
    @NonNull CoroutineScope scope
)

Creates a property delegate for a single process DataStore.

Public methods

dataStore

@NonNull
public static final ReadOnlyProperty<@NonNull Context, @NonNull DataStore<@NonNull T>> <T extends Object> dataStore(
    @NonNull String fileName,
    @NonNull Serializer<@NonNull T> serializer,
    @Nullable ReplaceFileCorruptionHandler<@NonNull T> corruptionHandler,
    @NonNull Function1<@NonNull Context, @NonNull List<@NonNull DataMigration<@NonNull T>>> produceMigrations,
    @NonNull CoroutineScope scope
)

Creates a property delegate for a single process DataStore. This should only be called once in a file (at the top level), and all usages of the DataStore should use a reference the same Instance. The receiver type for the property delegate must be an instance of Context.

This should only be used from a single application in a single classloader in a single process.

Example usage:

val Context.myDataStore by dataStore("filename", serializer)

class SomeClass(val context: Context) {
suspend fun update() = context.myDataStore.updateData {...}
}
Parameters
@NonNull String fileName

the filename relative to Context.applicationContext.filesDir that DataStore acts on. The File is obtained from dataStoreFile. It is created in the "/datastore" subdirectory.

@Nullable ReplaceFileCorruptionHandler<@NonNull T> corruptionHandler

The corruptionHandler is invoked if DataStore encounters a androidx.datastore.core.CorruptionException when attempting to read data. CorruptionExceptions are thrown by serializers when data can not be de-serialized.

@NonNull Function1<@NonNull Context, @NonNull List<@NonNull DataMigration<@NonNull T>>> produceMigrations

produce the migrations. The ApplicationContext is passed in to these callbacks as a parameter. DataMigrations are run before any access to data can occur. Each producer and migration may be run more than once whether or not it already succeeded (potentially because another migration failed or a write to disk failed.)

@NonNull CoroutineScope scope

The scope in which IO operations and transform functions will execute.

Returns
ReadOnlyProperty<@NonNull Context, @NonNull DataStore<@NonNull T>>

a property delegate that manages a datastore as a singleton.