Overview

Factory for DataSources.

Data-loading systems of an application or library can implement this interface to allow LiveDatas to be created. For example, Room can provide a DataSource.Factory for a given SQL query:

  @Dao
 interface UserDao {
     @Query("SELECT * FROM user ORDER BY lastName ASC")
    public abstract DataSource.Factory<Integer, User> usersByLastName();
 }
 

In the above sample, Integer is used because it is the Key type of PositionalDataSource. Currently, Room uses the LIMIT/OFFSET SQL keywords to page a large query with a PositionalDataSource.

Summary

Constructors
public	Factory()

Methods
public abstract DataSource<java.lang.Object, java.lang.Object>	create() Create a DataSource.
public DataSource.Factory<java.lang.Object, java.lang.Object>	map(Function<java.lang.Object, java.lang.Object> function) Applies the given function to each value emitted by DataSources produced by this Factory.
public DataSource.Factory<java.lang.Object, java.lang.Object>	mapByPage(Function<java.util.List, java.util.List> function) Applies the given function to each value emitted by DataSources produced by this Factory.
from java.lang.Object	clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructors

Methods

Create a DataSource.

The DataSource should invalidate itself if the snapshot is no longer valid. If a DataSource becomes invalid, the only way to query more data is to create a new DataSource from the Factory.

LivePagedListBuilder for example will construct a new PagedList and DataSource when the current DataSource is invalidated, and pass the new PagedList through the LiveData to observers.

Returns:

the new DataSource.

Applies the given function to each value emitted by DataSources produced by this Factory.

Same as DataSource.Factory.mapByPage(Function, List>), but operates on individual items.

Parameters:

function: Function that runs on each loaded item, returning items of a potentially new type.

Returns:

A new DataSource.Factory, which transforms items using the given function.

See also: DataSource.Factory.mapByPage(Function, List>), DataSource.map(Function), DataSource.mapByPage(Function, List>)

Applies the given function to each value emitted by DataSources produced by this Factory.

Same as DataSource.Factory.map(Function), but allows for batch conversions.

Parameters:

function: Function that runs on each loaded page, returning items of a potentially new type.

Returns:

A new DataSource.Factory, which transforms items using the given function.

See also: DataSource.Factory.map(Function), DataSource.map(Function), DataSource.mapByPage(Function, List>)