GroupedDataSource<PageKey, Parent, Value> class abstract

An extension of DataSource that automatically groups its items into sections based on a developer-defined condition.

Use this class to power GroupedPagingList or GroupedPagingGrid. To use it, you must extend it and implement the groupBy method, which defines how items are categorized into groups.

The GroupedDataSource listens for changes to the underlying flat list of items from DataSource and re-computes the grouped structure on demand, caching the result for efficiency.

Inheritance

Constructors

GroupedDataSource({Set<LoadErrorPolicy> errorPolicy = const {}})
Creates a GroupedDataSource and sets up a listener to invalidate the group cache when the underlying data changes.

Properties

errorPolicy ↔ Set<LoadErrorPolicy>
Defines the error handling policy for load operations. By default, all errors are shown in the UI.
getter/setter pairinherited
groupedValues → List<GroupedPageData<Parent, Value>>
Returns a cached, grouped list of data suitable for sectioned UI.
no setter
hashCode → int
The hash code for this object.
no setterinherited
notifier → PageManager<PageKey, Value>
The underlying state manager for the data source.
no setterinherited
onLoadFinished ↔ void Function(LoadAction<PageKey> action, LoadResult<PageKey, Value> result)?
A callback invoked after every load operation completes, providing the LoadResult. Useful for analytics or showing temporary error messages.
getter/setter pairinherited
onLoadStarted ↔ void Function(LoadAction<PageKey> action)?
A callback that is invoked just before a load operation begins. It provides the LoadAction that is about to be executed.
getter/setter pairinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

addListener(VoidCallback listener) → void
Registers a callback to be invoked when the data or loading state changes.
inherited
append() → Future<void>
Triggers an append operation to load data after the current items.
inherited
dispose() → void
Releases the resources used by this DataSource.
override
groupBy(Value value) → Parent
Extracts the group identifier (the "parent") from a given item.
insertItem(int index, Value item) → void
Inserts an item at the specified index and notifies listeners.
inherited
load(LoadAction<PageKey> action) → Future<LoadResult<PageKey, Value>>
Loads a page of data based on the specified LoadAction.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
prepend() → Future<void>
Triggers a prepend operation to load data before the current items.
inherited
refresh() → Future<void>
Triggers a full refresh of the data, discarding the existing items.
inherited
removeItem(int index) → void
Removes a single item at the specified index and notifies listeners.
inherited
removeItems(bool test(int index, Value item)) → void
Removes all items that satisfy the given test and notifies listeners.
inherited
removeListener(VoidCallback listener) → void
Removes a previously registered callback.
inherited
toString() → String
A string representation of this object.
inherited
updateItem(int index, Value update(Value item)) → void
Updates a single item in the list at the specified index.
inherited
updateItems(Value update(int index, Value item)) → void
Updates all items currently in the list and notifies listeners.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited