# PositionalDataSource

Artifact: [androidx.paging:paging-common](https://developer.android.com/jetpack/androidx/releases/paging) [View Source](https://cs.android.com/search?q=file:androidx/paging/PositionalDataSource.jvmAndAndroid.kt+class:androidx.paging.PositionalDataSource) 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 PositionalDataSource<T : Any> : DataSource<Int, T>
  ```

|---|---|---|
| [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)\<[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html), T\> ||
|   | ↳ | [androidx.paging.PositionalDataSource](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource) |

*** ** * ** ***

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 PositionalDataSource is deprecated and has been replaced by PagingSource, use this instead: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

Position-based data loader for a fixed-size, countable data set, supporting fixed-size loads at arbitrary page positions.

Extend PositionalDataSource if you can load pages of a requested size at arbitrary positions, and provide a fixed item count. If your data source can't support loading arbitrary requested page sizes (e.g. when network page size constraints are only known at runtime), either use `https://developer.android.com/reference/kotlin/androidx/paging/PageKeyedDataSource` or `https://developer.android.com/reference/kotlin/androidx/paging/ItemKeyedDataSource`, or pass the initial result with the two parameter `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialCallback#onResult(kotlin.collections.List,kotlin.Int,kotlin.Int)`.

Room can generate a Factory of PositionalDataSources for you:

```kotlin
@Dao
interface UserDao {
    @Query("SELECT * FROM user ORDER BY age DESC")
    public abstract DataSource.Factory<Integer, User> loadUsersByAgeDesc();
}
```

| Parameters |
|---|---|
| `<T : 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/PositionalDataSource`. |

## Summary

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` **This class is deprecated.** PositionalDataSource is deprecated and has been replaced by PagingSource |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

| ### Public companion functions |
|---|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | `[computeInitialLoadPosition](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#computeInitialLoadPosition(androidx.paging.PositionalDataSource.LoadInitialParams,kotlin.Int))( params: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialParams, totalCount: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html )` **This function is deprecated.** PositionalDataSource is deprecated and has been replaced by PagingSource | android |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | `[computeInitialLoadSize](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#computeInitialLoadSize(androidx.paging.PositionalDataSource.LoadInitialParams,kotlin.Int,kotlin.Int))( params: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialParams, initialLoadPosition: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, totalCount: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html )` **This function is deprecated.** PositionalDataSource is deprecated and has been replaced by PagingSource | android |

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

| ### Public functions |
|---|---|---|
| `abstract https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `@https://developer.android.com/reference/kotlin/androidx/annotation/WorkerThread [loadInitial](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#loadInitial(androidx.paging.PositionalDataSource.LoadInitialParams,androidx.paging.PositionalDataSource.LoadInitialCallback))( params: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialParams, callback: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialCallback<T> )` **This function is deprecated.** PositionalDataSource is deprecated and has been replaced by PagingSource | android |
| `abstract https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `@https://developer.android.com/reference/kotlin/androidx/annotation/WorkerThread [loadRange](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#loadRange(androidx.paging.PositionalDataSource.LoadRangeParams,androidx.paging.PositionalDataSource.LoadRangeCallback))( params: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadRangeParams, callback: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadRangeCallback<T> )` **This function is deprecated.** PositionalDataSource is deprecated and has been replaced by PagingSource | android |
| `final https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource<V>` | `<V : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html> [map](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#map(androidx.arch.core.util.Function))(function: https://developer.android.com/reference/kotlin/androidx/arch/core/util/Function<T, V>)` **This function is deprecated.** PositionalDataSource is deprecated and has been replaced by PagingSource | android |
| `final https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource<V>` | `<V : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html> [map](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#map(kotlin.Function1))(function: (T) -> V)` **This function is deprecated.** PositionalDataSource is deprecated and has been replaced by PagingSource | android |
| `final https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource<V>` | `<V : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html> [mapByPage](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#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<T>, https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<V>>)` **This function is deprecated.** PositionalDataSource is deprecated and has been replaced by PagingSource | android |
| `final https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource<V>` | `<V : https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html> [mapByPage](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#mapByPage(kotlin.Function1))(function: (https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<T>) -> https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<V>)` **This function is deprecated.** PositionalDataSource 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.** PositionalDataSource 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.** PositionalDataSource 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.** PositionalDataSource 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.** PositionalDataSource is deprecated and has been replaced by PagingSource
android

## Public companion functions

### computeInitialLoadPosition

android Added in [3.3.0](https://developer.android.com/jetpack/androidx/releases/paging#3.3.0) Deprecated in [3.3.0](https://developer.android.com/jetpack/androidx/releases/paging#3.3.0)

```
fun [computeInitialLoadPosition](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#computeInitialLoadPosition(androidx.paging.PositionalDataSource.LoadInitialParams,kotlin.Int))(
    params: PositionalDataSource.LoadInitialParams,
    totalCount: Int
): Int
```

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

Helper for computing an initial position in `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#loadInitial(androidx.paging.PositionalDataSource.LoadInitialParams)` when total data set size can be computed ahead of loading.

The value computed by this function will do bounds checking, page alignment, and positioning based on initial load size requested.

Example usage in a `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource` subclass:

```kotlin
class ItemDataSource extends PositionalDataSource<Item> {
    private int computeCount() {
        // actual count code here
    }

    private List<Item> loadRangeInternal(int startPosition, int loadCount) {
        // actual load code here
    }

    @Override
    public void loadInitial(@NonNull LoadInitialParams params,
        @NonNull LoadInitialCallback<Item> callback) {
        int totalCount = computeCount();
        int position = computeInitialLoadPosition(params, totalCount);
        int loadSize = computeInitialLoadSize(params, position, totalCount);
        callback.onResult(loadRangeInternal(position, loadSize), position, totalCount);
    }

    @Override
    public void loadRange(@NonNull LoadRangeParams params,
        @NonNull LoadRangeCallback<Item> callback) {
        callback.onResult(loadRangeInternal(params.startPosition, params.loadSize));
    }
}
```

| Parameters |
|---|---|
| `params: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialParams` | Params passed to `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#loadInitial(androidx.paging.PositionalDataSource.LoadInitialParams)`, including page size, and requested start / loadSize. |
| `totalCount: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Total size of the data set. |

| Returns |
|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Position to start loading at. |

| See also |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#computeInitialLoadSize(androidx.paging.PositionalDataSource.LoadInitialParams,kotlin.Int,kotlin.Int)` |   |

### computeInitialLoadSize

android Added in [3.3.0](https://developer.android.com/jetpack/androidx/releases/paging#3.3.0) Deprecated in [3.3.0](https://developer.android.com/jetpack/androidx/releases/paging#3.3.0)

```
fun [computeInitialLoadSize](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#computeInitialLoadSize(androidx.paging.PositionalDataSource.LoadInitialParams,kotlin.Int,kotlin.Int))(
    params: PositionalDataSource.LoadInitialParams,
    initialLoadPosition: Int,
    totalCount: Int
): Int
```

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

Helper for computing an initial load size in `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#loadInitial(androidx.paging.PositionalDataSource.LoadInitialParams)` when total data set size can be computed ahead of loading.

This function takes the requested load size, and bounds checks it against the value returned by `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#computeInitialLoadPosition(androidx.paging.PositionalDataSource.LoadInitialParams,kotlin.Int)`.

Example usage in a `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource` subclass:

```kotlin
class ItemDataSource extends PositionalDataSource<Item> {
    private int computeCount() {
        // actual count code here
    }

    private List<Item> loadRangeInternal(int startPosition, int loadCount) {
        // actual load code here
    }

    @Override
    public void loadInitial(@NonNull LoadInitialParams params,
        @NonNull LoadInitialCallback<Item> callback) {
        int totalCount = computeCount();
        int position = computeInitialLoadPosition(params, totalCount);
        int loadSize = computeInitialLoadSize(params, position, totalCount);
        callback.onResult(loadRangeInternal(position, loadSize), position, totalCount);
    }

    @Override
    public void loadRange(@NonNull LoadRangeParams params,
        @NonNull LoadRangeCallback<Item> callback) {
        callback.onResult(loadRangeInternal(params.startPosition, params.loadSize));
    }
}
```

| Parameters |
|---|---|
| `params: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialParams` | Params passed to `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#loadInitial(androidx.paging.PositionalDataSource.LoadInitialParams)`, including page size, and requested start / loadSize. |
| `initialLoadPosition: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Value returned by `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#computeInitialLoadPosition(androidx.paging.PositionalDataSource.LoadInitialParams,kotlin.Int)` |
| `totalCount: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Total size of the data set. |

| Returns |
|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | Number of items to load. |

| See also |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#computeInitialLoadPosition(androidx.paging.PositionalDataSource.LoadInitialParams,kotlin.Int)` |   |

## Public constructors

### PositionalDataSource

android

```
<T : Any> [PositionalDataSource](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#PositionalDataSource())()
```

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

| Parameters |
|---|---|
| `<T : 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/PositionalDataSource`. |

## Public functions

### 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)

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

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

Load initial list data.

This method is called to load the initial page(s) from the `https://developer.android.com/reference/kotlin/androidx/paging/DataSource`.

LoadResult list must be a multiple of pageSize to enable efficient tiling.

| Parameters |
|---|---|
| `params: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialParams` | Parameters for initial load, including requested start position, load size, and page size. |
| `callback: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialCallback<T>` | Callback that receives initial load data, including position and total data set size. |

### loadRange

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)

```
@WorkerThread
abstract fun [loadRange](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#loadRange(androidx.paging.PositionalDataSource.LoadRangeParams,androidx.paging.PositionalDataSource.LoadRangeCallback))(
    params: PositionalDataSource.LoadRangeParams,
    callback: PositionalDataSource.LoadRangeCallback<T>
): Unit
```

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

Called to load a range of data from the DataSource.

This method is called to load additional pages from the DataSource after the `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadInitialCallback` passed to dispatchLoadInitial has initialized a `https://developer.android.com/reference/kotlin/androidx/paging/PagedList`.

Unlike `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#loadInitial(androidx.paging.PositionalDataSource.LoadInitialParams)`, this method must return the number of items requested, at the position requested.

| Parameters |
|---|---|
| `params: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadRangeParams` | Parameters for load, including start position and load size. |
| `callback: https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource.LoadRangeCallback<T>` | Callback that receives loaded data. |

### map

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)

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

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

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 |
|---|---|
| `function: https://developer.android.com/reference/kotlin/androidx/arch/core/util/Function<T, V>` | Function that runs on each loaded item, returning items of a potentially new type. |

| Returns |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource<V>` | 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 <V : Any> [map](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#map(kotlin.Function1))(function: (T) -> V): PositionalDataSource<V>
```

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

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 |
|---|---|
| `function: (T) -> V` | Function that runs on each loaded item, returning items of a potentially new type. |

| Returns |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource<V>` | 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 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)

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

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

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 |
|---|---|
| `function: https://developer.android.com/reference/kotlin/androidx/arch/core/util/Function<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<T>, https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<V>>` | Function that runs on each loaded page, returning items of a potentially new type. |

| Returns |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource<V>` | 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 <V : Any> [mapByPage](https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource#mapByPage(kotlin.Function1))(function: (List<T>) -> List<V>): PositionalDataSource<V>
```

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

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 |
|---|---|
| `function: (https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<T>) -> https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<V>` | Function that runs on each loaded page, returning items of a potentially new type. |

| Returns |
|---|---|
| `https://developer.android.com/reference/kotlin/androidx/paging/PositionalDataSource<V>` | 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)` |   |