# PageKeyedDataSource

Artifact: [androidx.paging:paging-common](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/PageKeyedDataSource.jvmAndAndroid.kt+class:androidx.paging.PageKeyedDataSource) Added in [2.0.0](https://developer.android.com/jetpack/androidx/releases/paging#2.0.0) Deprecated in [3.0.0](https://developer.android.com/jetpack/androidx/releases/paging#3.0.0)

*** ** * ** ***

Common/AllAndroid/JVMNative/C/iOSJavaScript
- android

  ```
  abstract class PageKeyedDataSource<Key : Any, Value : Any> : DataSource<Key, Value>
  ```

|---|---|---|
| [kotlin.Any](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html) |||
| ↳ | [androidx.paging.DataSource](https://developer.android.com/reference/kotlin/androidx/paging/DataSource)\<Key, Value\> ||
|   | ↳ | [androidx.paging.PageKeyedDataSource](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource) |

*** ** * ** ***

> [!CAUTION]
> **This class is deprecated.**   
> PageKeyedDataSource is deprecated and has been replaced by PagingSource, use this instead:
>
> ```kotlin
> PagingSource<Key, Value>
> ```

Incremental data loader for page-keyed content, where requests return keys for next/previous pages.

Implement a `https://developer.android.com/reference/kotlin/androidx/paging/DataSource` using `https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource` if you need to use data from page `N - 1` to load page `N`. This is common, for example, in network APIs that include a next/previous link or key with each page load.

The `InMemoryByPageRepository` in the [PagingWithNetworkSample](https://github.com/googlesamples/android-architecture-components/blob/master/PagingWithNetworkSample/README.md) shows how to implement a network PageKeyedDataSource using [Retrofit](https://square.github.io/retrofit/), while handling swipe-to-refresh, network errors, and retry.

| Parameters |
|---|---|
| `<Key : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` | Type of data used to query Value types out of the `https://developer.android.com/reference/kotlin/androidx/paging/DataSource`. |
| `<Value : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` | Type of items being loaded by the `https://developer.android.com/reference/kotlin/androidx/paging/DataSource`. |

## Summary

| ### Nested types |
|---|
| `abstract class https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadCallback<Key : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html?, Value : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html?>` **This class is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource |
| `abstract class https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadInitialCallback<Key : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html?, Value : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html?>` **This class is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource |
| `open class https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadInitialParams<Key : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` **This class is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource |
| `open class https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadParams<Key : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` **This class is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource |

| ### Public constructors |
|---|---|
| `<Key : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html, Value : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html> [PageKeyedDataSource](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#PageKeyedDataSource())()` **This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource | android |

| ### Public functions |
|---|---|---|
| `abstract https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `[loadAfter](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#loadAfter(androidx.paging.PageKeyedDataSource.LoadParams,androidx.paging.PageKeyedDataSource.LoadCallback))( params: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadParams<Key>, callback: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadCallback<Key, Value> )` **This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource | android |
| `abstract https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `[loadBefore](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#loadBefore(androidx.paging.PageKeyedDataSource.LoadParams,androidx.paging.PageKeyedDataSource.LoadCallback))( params: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadParams<Key>, callback: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadCallback<Key, Value> )` **This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource | android |
| `abstract https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `[loadInitial](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#loadInitial(androidx.paging.PageKeyedDataSource.LoadInitialParams,androidx.paging.PageKeyedDataSource.LoadInitialCallback))( params: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadInitialParams<Key>, callback: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadInitialCallback<Key, Value> )` **This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource | android |
| `final https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource<Key, ToValue>` | `<ToValue : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html> [map](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#map(androidx.arch.core.util.Function))(function: https://developer.android.com/reference/kotlin/androidx/arch/core/util/Function<Value, ToValue>)` **This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource | android |
| `final https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource<Key, ToValue>` | `<ToValue : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html> [map](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#map(kotlin.Function1))(function: (Value) -> ToValue)` **This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource | android |
| `final https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource<Key, ToValue>` | `<ToValue : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html> [mapByPage](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#mapByPage(androidx.arch.core.util.Function))(function: https://developer.android.com/reference/kotlin/androidx/arch/core/util/Function<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<Value>, https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<ToValue>>)` **This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource | android |
| `final https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource<Key, ToValue>` | `<ToValue : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html> [mapByPage](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#mapByPage(kotlin.Function1))(function: (https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<Value>) -> https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<ToValue>)` **This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource | android |

### Inherited functions

From [androidx.paging.DataSource](https://developer.android.com/reference/kotlin/androidx/paging/DataSource) `open https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` `@https://developer.android.com/reference/kotlin/androidx/annotation/AnyThread
[addInvalidatedCallback](https://developer.android.com/reference/kotlin/androidx/paging/DataSource#addInvalidatedCallback(androidx.paging.DataSource.InvalidatedCallback))(
onInvalidatedCallback: https://developer.android.com/reference/kotlin/androidx/paging/DataSource.InvalidatedCallback
)`

**This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource
android `open https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` `@https://developer.android.com/reference/kotlin/androidx/annotation/AnyThread
[invalidate](https://developer.android.com/reference/kotlin/androidx/paging/DataSource#invalidate())()`

**This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource
android `open https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` `@https://developer.android.com/reference/kotlin/androidx/annotation/AnyThread
[removeInvalidatedCallback](https://developer.android.com/reference/kotlin/androidx/paging/DataSource#removeInvalidatedCallback(androidx.paging.DataSource.InvalidatedCallback))(
onInvalidatedCallback: https://developer.android.com/reference/kotlin/androidx/paging/DataSource.InvalidatedCallback
)`

**This function is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource
android

### Inherited properties

From [androidx.paging.DataSource](https://developer.android.com/reference/kotlin/androidx/paging/DataSource) `open https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html` `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#isInvalid()`

**This property is deprecated.** PageKeyedDataSource is deprecated and has been replaced by PagingSource
android

## Public constructors

### PageKeyedDataSource

android

```
<Key : Any, Value : Any> [PageKeyedDataSource](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#PageKeyedDataSource())()
```

> [!CAUTION]
> **This function is deprecated.**   
> PageKeyedDataSource is deprecated and has been replaced by PagingSource, use this instead:
>
> ```kotlin
> PagingSource<Key, Value>
> ```

| Parameters |
|---|---|
| `<Key : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` | Type of data used to query Value types out of the `https://developer.android.com/reference/kotlin/androidx/paging/DataSource`. |
| `<Value : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` | Type of items being loaded by the `https://developer.android.com/reference/kotlin/androidx/paging/DataSource`. |

## Public functions

### loadAfter

android Added in [2.0.0](https://developer.android.com/jetpack/androidx/releases/paging#2.0.0) Deprecated in [3.0.0](https://developer.android.com/jetpack/androidx/releases/paging#3.0.0)

```
abstract fun [loadAfter](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#loadAfter(androidx.paging.PageKeyedDataSource.LoadParams,androidx.paging.PageKeyedDataSource.LoadCallback))(
    params: PageKeyedDataSource.LoadParams<Key>,
    callback: PageKeyedDataSource.LoadCallback<Key, Value>
): Unit
```

> [!CAUTION]
> **This function is deprecated.**   
> PageKeyedDataSource is deprecated and has been replaced by PagingSource, use this instead:
>
> ```kotlin
> PagingSource<Key, Value>
> ```

Append page with the key specified by `https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadParams#key()`.

It's valid to return a different list size than the page size if it's easier, e.g. if your backend defines page sizes. It is generally preferred to increase the number loaded than reduce.

Data may be passed synchronously during the load method, or deferred and called at a later time. Further loads going down will be blocked until the callback is called.

If data cannot be loaded (for example, if the request is invalid, or the data would be stale and inconsistent), it is valid to call `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#invalidate()` to invalidate the data source, and prevent further loading.

| Parameters |
|---|---|
| `params: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadParams<Key>` | Parameters for the load, including the key for the new page, and requested load size. |
| `callback: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadCallback<Key, Value>` | Callback that receives loaded data. |

### loadBefore

android Added in [2.0.0](https://developer.android.com/jetpack/androidx/releases/paging#2.0.0) Deprecated in [3.0.0](https://developer.android.com/jetpack/androidx/releases/paging#3.0.0)

```
abstract fun [loadBefore](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#loadBefore(androidx.paging.PageKeyedDataSource.LoadParams,androidx.paging.PageKeyedDataSource.LoadCallback))(
    params: PageKeyedDataSource.LoadParams<Key>,
    callback: PageKeyedDataSource.LoadCallback<Key, Value>
): Unit
```

> [!CAUTION]
> **This function is deprecated.**   
> PageKeyedDataSource is deprecated and has been replaced by PagingSource, use this instead:
>
> ```kotlin
> PagingSource<Key, Value>
> ```

Prepend page with the key specified by `https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadParams#key()`.

It's valid to return a different list size than the page size if it's easier, e.g. if your backend defines page sizes. It is generally preferred to increase the number loaded than reduce.

Data may be passed synchronously during the load method, or deferred and called at a later time. Further loads going down will be blocked until the callback is called.

If data cannot be loaded (for example, if the request is invalid, or the data would be stale and inconsistent), it is valid to call `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#invalidate()` to invalidate the data source, and prevent further loading.

| Parameters |
|---|---|
| `params: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadParams<Key>` | Parameters for the load, including the key for the new page, and requested load size. |
| `callback: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadCallback<Key, Value>` | Callback that receives loaded data. |

### loadInitial

android Added in [2.0.0](https://developer.android.com/jetpack/androidx/releases/paging#2.0.0) Deprecated in [3.0.0](https://developer.android.com/jetpack/androidx/releases/paging#3.0.0)

```
abstract fun [loadInitial](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#loadInitial(androidx.paging.PageKeyedDataSource.LoadInitialParams,androidx.paging.PageKeyedDataSource.LoadInitialCallback))(
    params: PageKeyedDataSource.LoadInitialParams<Key>,
    callback: PageKeyedDataSource.LoadInitialCallback<Key, Value>
): Unit
```

> [!CAUTION]
> **This function is deprecated.**   
> PageKeyedDataSource is deprecated and has been replaced by PagingSource, use this instead:
>
> ```kotlin
> PagingSource<Key, Value>
> ```

Load initial data.

This method is called first to initialize a PagedList with data. If it's possible to count the items that can be loaded by the DataSource, it's recommended to pass the loaded data to the callback via the three-parameter `https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadInitialCallback#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int,kotlin.Any,kotlin.Any)`. This enables PagedLists presenting data from this source to display placeholders to represent unloaded items.

`https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadInitialParams#requestedLoadSize()` is a hint, not a requirement, so it may be may be altered or ignored.

| Parameters |
|---|---|
| `params: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadInitialParams<Key>` | Parameters for initial load, including requested load size. |
| `callback: https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource.LoadInitialCallback<Key, Value>` | Callback that receives initial load data. |

### map

android

```
final fun <ToValue : Any> [map](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#map(androidx.arch.core.util.Function))(function: Function<Value, ToValue>): PageKeyedDataSource<Key, ToValue>
```

> [!CAUTION]
> **This function is deprecated.**   
> PageKeyedDataSource is deprecated and has been replaced by PagingSource, use this instead:
>
> ```kotlin
> PagingSource<Key, Value>
> ```

Applies the given function to each value emitted by the DataSource.

Same as `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#mapByPage(androidx.arch.core.util.Function)`, but operates on individual items.

| Parameters |
|---|---|
| `<ToValue : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` | Type of items produced by the new DataSource, from the passed function. |
| `function: https://developer.android.com/reference/kotlin/androidx/arch/core/util/Function<Value, ToValue>` | Function that runs on each loaded item, returning items of a potentially new type. |

| Returns |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource<Key, ToValue>` | A new DataSource, which transforms items using the given function. |

| See also |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#mapByPage(androidx.arch.core.util.Function)` |   |
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource.Factory#map(androidx.arch.core.util.Function)` |   |
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource.Factory#mapByPage(androidx.arch.core.util.Function)` |   |

### map

android Added in [3.0.0](https://developer.android.com/jetpack/androidx/releases/paging#3.0.0) Deprecated in [3.0.0](https://developer.android.com/jetpack/androidx/releases/paging#3.0.0)

```
final fun <ToValue : Any> [map](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#map(kotlin.Function1))(function: (Value) -> ToValue): PageKeyedDataSource<Key, ToValue>
```

> [!CAUTION]
> **This function is deprecated.**   
> PageKeyedDataSource is deprecated and has been replaced by PagingSource, use this instead:
>
> ```kotlin
> PagingSource<Key, Value>
> ```

Applies the given function to each value emitted by the DataSource.

An overload of `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#map(kotlin.Function1)` that accepts a kotlin function type.

Same as `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#mapByPage(androidx.arch.core.util.Function)`, but operates on individual items.

| Parameters |
|---|---|
| `<ToValue : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` | Type of items produced by the new DataSource, from the passed function. |
| `function: (Value) -> ToValue` | Function that runs on each loaded item, returning items of a potentially new type. |

| Returns |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource<Key, ToValue>` | A new DataSource, which transforms items using the given function. |

| See also |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#mapByPage(androidx.arch.core.util.Function)` |   |
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource.Factory#map(androidx.arch.core.util.Function)` |   |

### mapByPage

android

```
final fun <ToValue : Any> [mapByPage](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#mapByPage(androidx.arch.core.util.Function))(function: Function<List<Value>, List<ToValue>>): PageKeyedDataSource<Key, ToValue>
```

> [!CAUTION]
> **This function is deprecated.**   
> PageKeyedDataSource is deprecated and has been replaced by PagingSource, use this instead:
>
> ```kotlin
> PagingSource<Key, Value>
> ```

Applies the given function to each value emitted by the DataSource.

Same as `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#map(androidx.arch.core.util.Function)`, but allows for batch conversions.

| Parameters |
|---|---|
| `<ToValue : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` | Type of items produced by the new DataSource, from the passed function. |
| `function: https://developer.android.com/reference/kotlin/androidx/arch/core/util/Function<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<Value>, https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<ToValue>>` | Function that runs on each loaded page, returning items of a potentially new type. |

| Returns |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource<Key, ToValue>` | A new DataSource, which transforms items using the given function. |

| See also |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#map(androidx.arch.core.util.Function)` |   |
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource.Factory#map(androidx.arch.core.util.Function)` |   |
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource.Factory#mapByPage(androidx.arch.core.util.Function)` |   |

### mapByPage

android

```
final fun <ToValue : Any> [mapByPage](https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource#mapByPage(kotlin.Function1))(function: (List<Value>) -> List<ToValue>): PageKeyedDataSource<Key, ToValue>
```

> [!CAUTION]
> **This function is deprecated.**   
> PageKeyedDataSource is deprecated and has been replaced by PagingSource, use this instead:
>
> ```kotlin
> PagingSource<Key, Value>
> ```

Applies the given function to each value emitted by the DataSource.

An overload of `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#mapByPage(kotlin.Function1)` that accepts a kotlin function type.

Same as `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#map(androidx.arch.core.util.Function)`, but allows for batch conversions.

| Parameters |
|---|---|
| `<ToValue : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html>` | Type of items produced by the new DataSource, from the passed function. |
| `function: (https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<Value>) -> https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<ToValue>` | Function that runs on each loaded page, returning items of a potentially new type. |

| Returns |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource<Key, ToValue>` | A new `https://developer.android.com/reference/kotlin/androidx/paging/DataSource`, which transforms items using the given function. |

| See also |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource#map(androidx.arch.core.util.Function)` |   |
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource.Factory#map(androidx.arch.core.util.Function)` |   |
| `https://developer.android.com/reference/kotlin/androidx/paging/DataSource.Factory#mapByPage(androidx.arch.core.util.Function)` |   |