> For the complete documentation index, see [llms.txt](https://cognitox.gitbook.io/cognito-kmm-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cognitox.gitbook.io/cognito-kmm-docs/feautures/datastore.md).

# DataStore

### Local Data Storage with DataStore in KMM

This document explains how to implement a shared local data storage solution using DataStore for both Android and iOS.

**DataStore:**

DataStore is a KMM library that provides a consistent API for storing and retrieving key-value data persistently on the device. It offers advantages over platform-specific solutions by allowing you to write code once and share it across platforms.

**Usage:**

1. **Dependency:** Include the `kotlinx-coroutines-datastore` library in your shared module.
2. **Injection:** In your KMM code, inject the `DataStore<Preferences>` instance using a dependency injection framework.

Kotlin

```
class MyViewModel @Inject constructor(private val dataStore: DataStore<Preferences>) {
    // ...
}
```

3. **Data Access:** Use the `dataStore` instance to access and manipulate your local data. The provided example demonstrates how to retrieve authentication information:

Kotlin

```
fun getAuth(): Flow<RemoteData<Auth>> =
    dataStore.data.map { pref ->
        pref[authKey]?.let {
            logD(Tag.Auth.LoadAuthFromStorage, it)
            Json.decodeFromString<Auth>(it).right()
        }.toOption()
    }
```

**Explanation of the Example:**

* `getAuth` function returns a `Flow<RemoteData<Auth>>`.
* It uses `dataStore.data` to access the latest data stored in the preferences.
* The `map` operation transforms the retrieved data:
  * It checks if the `authKey` exists in the preferences.
  * If found, it decodes the stored JSON string into an `Auth` object using `Json.decodeFromString` and wraps it in `Right` of `Either`.
  * If the key is not found, the function returns `None` of `Option` representing missing data.

**Additional Notes:**

* You can store various data types by converting them to JSON strings and vice versa.
* You can use other DataStore operations like `updateData` and `delete` to manage your local data.
* Consider using dedicated libraries like `kotlinx-serialization` for more efficient object serialization and deserialization.

By using DataStore, you can achieve a unified approach for local data storage in your KMM applications, simplifying code development and platform compatibility.