flutter_paging_viewmodel_example_1

chayanforyou

Jun 19th, 2025

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class LocationViewModel extends StateNotifier<AsyncValue<List<Places>>> {
final List<Places> initialLocations;
final String employeeId;
final int year;
final int month;
final String shift;
LocationViewModel({
required this.initialLocations,
required this.employeeId,
required this.year,
required this.month,
required this.shift,
}) : super(const AsyncValue.loading()) {
_fetchLocations();
}
String _searchTerm = '';
List<Places> _locations = [];
// Getter for the selected locations
List<Places> get selectedLocations => initialLocations;
// Method to fetch locations
Future<void> _fetchLocations() async {
try {
state = const AsyncValue.loading();
final response = await TourPlanRepository.instance.getTourPlanLocation(employeeId, year, month, shift);
final locations = response.data ?? [];
_locations = locations
.map((location) => location.copyWith(
selected: initialLocations.any((loc) => loc.uniqueKey == location.uniqueKey),
)).toList();
state = AsyncValue.data(_locations);
} catch (e, stackTrace) {
state = AsyncValue.error(e, stackTrace);
}
}
// Method to update the search term
void updateSearchTerm(String term) {
_searchTerm = term.trim();
state = AsyncValue.data(_filterLocations());
}
// Method to toggle the selection of a location
void toggleSelection(Places location) {
final index = _locations.indexWhere((l) => l.uniqueKey == location.uniqueKey);
if (index != -1) {
final isSelected = _locations[index].selected;
// Update the main list
_locations[index] = _locations[index].copyWith(selected: !isSelected);
// Update the selected list
if (isSelected) {
initialLocations.removeWhere((l) => l.uniqueKey == location.uniqueKey);
} else {
initialLocations.add(_locations[index]);
}
// Update state without resetting the filtered list
state = AsyncValue.data(_filterLocations());
}
}
// Method to filter locations based on search term
List<Places> _filterLocations() {
return _locations.where((location) {
return location.locationName?.toLowerCase().contains(_searchTerm.toLowerCase()) ?? false;
}).toList();
}
}
final locationViewModelProvider =
StateNotifierProvider.family.autoDispose<LocationViewModel, AsyncValue<List<Places>>, LocationQueryParams>(
(ref, params) => LocationViewModel(
initialLocations: params.initialLocations,
employeeId: params.employeeId,
year: params.year,
month: params.month,
shift: params.shift,
),
);
// --------------------------------------------------
class LocationViewModel extends StateNotifier<PagingState<int, Places>> {
final List<Places> initialLocations;
final int year;
final int month;
final Debouncer _debounce = Debouncer();
String? _searchTerm;
LocationViewModel({
required this.initialLocations,
required this.year,
required this.month,
}) : super(PagingState());
List<Places> get selectedLocations => initialLocations;
/// Fetches the next page of data
Future<void> fetchNextPage() async {
if (state.isLoading) return;
state = state.copyWith(isLoading: true, error: null);
try {
final newKey = state.keys?.isNotEmpty == true ? state.keys!.last + 1 : 0;
final response = await TourPlanRepository.instance.getTourPlanLocation(year, month, newKey, _searchTerm);
final locations = response.data.content ?? [];
final newItems = locations.map((location) {
return location.copyWith(
selected: initialLocations.any((loc) => loc.id == location.id),
);
}).toList();
state = state.copyWith(
pages: [...?state.pages, newItems],
keys: [...?state.keys, newKey],
hasNextPage: response.data.hasNext,
isLoading: false,
);
} catch (error) {
state = state.copyWith(
error: error,
isLoading: false,
);
}
}
/// Updates search term and refreshes the list
void updateSearchTerm(String searchTerm) {
_searchTerm = searchTerm;
_debounce.run(() {
refreshList();
});
}
/// Clear search and refreshes the list
void clearSearchTerm() {
_searchTerm = null;
_debounce.run(() {
refreshList();
});
}
/// Refreshes the list and fetches the first page
void refreshList() {
state = PagingState();
fetchNextPage();
}
void toggleSelection(Places location) {
final updatedPages = state.pages?.map((page) {
return page.map((loc) {
if (loc.id == location.id) {
return loc.copyWith(selected: !(loc.selected));
}
return loc;
}).toList();
}).toList();
state = state.copyWith(pages: updatedPages);
if (location.selected == true) {
initialLocations.remove(location);
} else {
initialLocations.add(location);
}
}
}
final locationViewModelProvider =
StateNotifierProvider.family.autoDispose<LocationViewModel, PagingState<int, Places>, LocationQueryParams>(
(ref, params) => LocationViewModel(
initialLocations: params.initialLocations,
year: params.year,
month: params.month,
),
);
// --------------------------------------------------
class LocationViewModel extends StateNotifier<AsyncValue<List<Places>>> {
final List<Places> initialLocations;
final String employeeId;
final int year;
final int month;
final Debouncer _debounce = Debouncer();
String _searchTerm = '';
LocationViewModel({
required this.initialLocations,
required this.employeeId,
required this.year,
required this.month,
}) : super(const AsyncValue.loading()) {
_fetchLocations();
}
String get searchTerm => _searchTerm;
// Method to fetch locations from the API based on the search term
Future<void> _fetchLocations() async {
try {
state = const AsyncValue.loading();
final response = await TourPlanRepository.instance.getTourPlanLocation(employeeId, year, month);
final locations = response.data ?? [];
// Update the state with the new list of places
state = AsyncValue.data(
locations.map((location) {
return location.copyWith(
selected: initialLocations.any((loc) => loc.id == location.id),
);
}).toList(),
);
} catch (e, stackTrace) {
state = AsyncValue.error(e, stackTrace);
}
}
// Method to update the search term with debounce
void updateSearchTerm(String term) {
_searchTerm = term.trim();
_debounce.run(() {
_fetchLocations();
});
}
// Method to toggle the selection of a location
void toggleSelection(Places location) {
final locations = state.value ?? [];
final index = locations.indexWhere((l) => l.id == location.id);
if (index == -1) return;
final isSelected = locations[index].selected;
final updatedLocation = locations[index].copyWith(selected: !isSelected);
locations[index] = updatedLocation;
state = AsyncValue.data(locations);
if (isSelected) {
initialLocations.removeWhere((l) => l.id == location.id);
} else {
initialLocations.add(updatedLocation);
}
}
// Getter for the selected locations
List<Places> get selectedLocations => initialLocations;
}
final locationViewModelProvider =
StateNotifierProvider.family.autoDispose<LocationViewModel, AsyncValue<List<Places>>, LocationQueryParams>(
(ref, params) => LocationViewModel(
initialLocations: params.initialLocations,
employeeId: params.employeeId,
year: params.year,
month: params.month,
),
);

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