datastore-core/androidx.datastore.core/DataStore

DataStore

interface DataStore<T>(source)

DataStore provides a safe and durable way to store small amounts of data, such as preferences and application state. It does not support partial updates: if any field is modified, the whole object will be serialized and persisted to disk. If you want partial updates, consider the Room API (SQLite).

DataStore provides ACID guarantees. It is thread-safe, and non-blocking. In particular, it addresses these design shortcomings of the SharedPreferences API:

  1. Synchronous API encourages StrictMode violations

  2. apply() and commit() have no mechanism of signalling errors

  3. apply() will block the UI thread on fsync()

  4. Not durable – it can returns state that is not yet persisted

  5. No consistency or transactional semantics

  6. Throws runtime exception on parsing errors

  7. Exposes mutable references to its internal state

Functions

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abstract suspend fun updateData(transform: suspend (t: T) -> T): T

Updates the data transactionally in an atomic read-modify-write operation. All operations are serialized, and the transform itself is a coroutine so it can perform heavy work such as RPCs.

Properties

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abstract val data: Flow<T>

Provides efficient, cached (when possible) access to the latest durably persisted state. The flow will always either emit a value or throw an exception encountered when attempting to read from disk. If an exception is encountered, collecting again will attempt to read the data again.