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Merged
merged 4 commits into from
Oct 2, 2020
Merged

LiveList: preloadedColumns #458

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e949733
LiveList: added preloadedColumns
fischerscode Sep 25, 2020
9e0c64f
LiveList: fixed bug with lazyloading=false
fischerscode Sep 27, 2020
0b6b1f9
formatting
fischerscode Sep 27, 2020
5063456
Add README section for flutter
fischerscode Oct 2, 2020
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81 changes: 49 additions & 32 deletions packages/dart/lib/src/utils/parse_live_list.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -2,34 +2,47 @@ part of flutter_parse_sdk;

// ignore_for_file: invalid_use_of_protected_member
class ParseLiveList<T extends ParseObject> {
ParseLiveList._(this._query, this._listeningIncludes, this._lazyLoading) {
ParseLiveList._(this._query, this._listeningIncludes, this._lazyLoading,
{List<String> preloadedColumns = const <String>[]})
: _preloadedColumns = preloadedColumns {
_debug = isDebugEnabled();
}

static Future<ParseLiveList<T>> create<T extends ParseObject>(
QueryBuilder<T> _query,
{bool listenOnAllSubItems,
List<String> listeningIncludes,
bool lazyLoading = true}) {
QueryBuilder<T> _query, {
bool listenOnAllSubItems,
List<String> listeningIncludes,
bool lazyLoading = true,
List<String> preloadedColumns,
}) {
final ParseLiveList<T> parseLiveList = ParseLiveList<T>._(
_query,
listenOnAllSubItems == true
? _toIncludeMap(
_query.limiters['include']?.toString()?.split(',') ??
<String>[])
: _toIncludeMap(listeningIncludes ?? <String>[]),
lazyLoading);
_query,
listenOnAllSubItems == true
? _toIncludeMap(
_query.limiters['include']?.toString()?.split(',') ?? <String>[])
: _toIncludeMap(listeningIncludes ?? <String>[]),
lazyLoading,
preloadedColumns: preloadedColumns,
);

return parseLiveList._init().then((_) {
return parseLiveList;
});
}

final QueryBuilder<T> _query;
//The included Items, where LiveList should look for updates.
final Map<String, dynamic> _listeningIncludes;
final bool _lazyLoading;
final List<String> _preloadedColumns;

List<ParseLiveListElement<T>> _list = List<ParseLiveListElement<T>>();
StreamController<ParseLiveListEvent<T>> _eventStreamController;
int _nextID = 0;
bool _debug;

int get nextID => _nextID++;

/// is object1 listed after object2?
/// can return null
bool after(T object1, T object2) {
Expand Down Expand Up @@ -84,14 +97,6 @@ class ParseLiveList<T extends ParseObject> {
return null;
}

int get nextID => _nextID++;

final QueryBuilder<T> _query;
//The included Items, where LiveList should look for updates.
final Map<String, dynamic> _listeningIncludes;

final bool _lazyLoading;

int get size {
return _list.length;
}
Expand Down Expand Up @@ -128,17 +133,17 @@ class ParseLiveList<T extends ParseObject> {
if (_debug)
print('ParseLiveList: lazyLoading is ${_lazyLoading ? 'on' : 'off'}');
if (_lazyLoading) {
if (query.limiters.containsKey('order')) {
query.keysToReturn(
query.limiters['order'].toString().split(',').map((String string) {
if (string.startsWith('-')) {
return string.substring(1);
}
return string;
}).toList());
} else {
query.keysToReturn(List<String>());
}
final List<String> keys = _preloadedColumns?.toList() ?? <String>[];
if (_lazyLoading && query.limiters.containsKey('order'))
keys.addAll(
query.limiters['order'].toString().split(',').map((String string) {
if (string.startsWith('-')) {
return string.substring(1);
}
return string;
}),
);
query.keysToReturn(keys);
}
return await query.query<T>();
}
Expand Down Expand Up @@ -449,6 +454,13 @@ class ParseLiveList<T extends ParseObject> {
return null;
}

T getPreLoadedAt(int index) {
if (index < _list.length) {
return _list[index].object;
}
return null;
}

void dispose() {
if (_liveQuerySubscription != null) {
LiveQuery().client.unSubscribe(_liveQuerySubscription);
Expand Down Expand Up @@ -739,12 +751,17 @@ typedef StreamGetter<T extends ParseObject> = Stream<T> Function();
typedef DataGetter<T extends ParseObject> = T Function();

class ParseLiveListElementSnapshot<T extends ParseObject> {
ParseLiveListElementSnapshot({this.loadedData, this.error});
ParseLiveListElementSnapshot(
{this.loadedData, this.error, this.preLoadedData});

final T loadedData;
final T preLoadedData;

final ParseError error;

bool get hasData => loadedData != null;

bool get hasPreLoadedData => preLoadedData != null;

bool get failed => error != null;
}
32 changes: 32 additions & 0 deletions packages/flutter/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -597,6 +597,38 @@ To activate listening for updates on all included objects, add `listenOnAllSubIt
If you want ParseLiveList to listen for updates on only some sub-objects, use `listeningIncludes: const <String>[/*all the included sub-objects*/]` instead.
Just as QueryBuilder, ParseLiveList supports nested sub-objects too.

### Lazy loading
By default, ParseLiveList lazy loads the content.
You can avoid that by setting `lazyLoading: false`.
In case you want to use lazyLoading but you need some columns to be preloaded, you can provide a list of `preloadedColumns`.
Preloading fields of a pointer is supported by using the dot-notation.
You can access the preloaded data is stored in the `preLoadedData` field of the `ParseLiveListElementSnapshot`.
```dart
ParseLiveListWidget<ParseObject>(
query: query,
lazyLoading: true,
preloadedColumns: ["test1", "sender.username"],
childBuilder:
(BuildContext context, ParseLiveListElementSnapshot<ParseObject> snapshot) {
if (snapshot.failed) {
return const Text('something went wrong!');
} else if (snapshot.hasData) {
return ListTile(
title: Text(
snapshot.loadedData.get<String>("text"),
),
);
} else {
return ListTile(
title: Text(
"loading comment from: ${snapshot.preLoadedData?.get<ParseObject>("sender")?.get<String>("username")}",
),
);
}
},
);
```

**NOTE:** To use this features you have to enable [Live Queries](#live-queries) first.

## Users
Expand Down
28 changes: 20 additions & 8 deletions packages/flutter/lib/src/utils/parse_live_list.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ class ParseLiveListWidget<T extends sdk.ParseObject> extends StatefulWidget {
this.listenOnAllSubItems,
this.listeningIncludes,
this.lazyLoading = true,
this.preloadedColumns,
}) : super(key: key);

final sdk.QueryBuilder<T> query;
Expand All @@ -42,6 +43,7 @@ class ParseLiveListWidget<T extends sdk.ParseObject> extends StatefulWidget {
final List<String> listeningIncludes;

final bool lazyLoading;
final List<String> preloadedColumns;

@override
_ParseLiveListWidgetState<T> createState() => _ParseLiveListWidgetState<T>(
Expand All @@ -50,6 +52,7 @@ class ParseLiveListWidget<T extends sdk.ParseObject> extends StatefulWidget {
listenOnAllSubItems: listenOnAllSubItems,
listeningIncludes: listeningIncludes,
lazyLoading: lazyLoading,
preloadedColumns: preloadedColumns,
);

static Widget defaultChildBuilder<T extends sdk.ParseObject>(
Expand Down Expand Up @@ -79,12 +82,14 @@ class _ParseLiveListWidgetState<T extends sdk.ParseObject>
@required this.removedItemBuilder,
bool listenOnAllSubItems,
List<String> listeningIncludes,
bool lazyLoading = true}) {
bool lazyLoading = true,
List<String> preloadedColumns}) {
sdk.ParseLiveList.create(
query,
listenOnAllSubItems: listenOnAllSubItems,
listeningIncludes: listeningIncludes,
lazyLoading: lazyLoading,
preloadedColumns: preloadedColumns,
).then((sdk.ParseLiveList<T> value) {
setState(() {
_liveList = value;
Expand All @@ -107,6 +112,7 @@ class _ParseLiveListWidgetState<T extends sdk.ParseObject>
sizeFactor: animation,
duration: widget.duration,
loadedData: () => event.object,
preLoadedData: () => event.object,
),
duration: widget.duration);
}
Expand Down Expand Up @@ -146,6 +152,7 @@ class _ParseLiveListWidgetState<T extends sdk.ParseObject>
_liveList?.getIdentifier(index) ?? '_NotFound'),
stream: () => _liveList?.getAt(index),
loadedData: () => _liveList?.getLoadedAt(index),
preLoadedData: () => _liveList?.getPreLoadedAt(index),
sizeFactor: animation,
duration: widget.duration,
childBuilder:
Expand All @@ -168,39 +175,44 @@ class ParseLiveListElementWidget<T extends sdk.ParseObject>
{Key key,
this.stream,
this.loadedData,
this.preLoadedData,
@required this.sizeFactor,
@required this.duration,
@required this.childBuilder})
: super(key: key);

final sdk.StreamGetter<T> stream;
final sdk.DataGetter<T> loadedData;
final sdk.DataGetter<T> preLoadedData;
final Animation<double> sizeFactor;
final Duration duration;
final ChildBuilder<T> childBuilder;

@override
_ParseLiveListElementWidgetState<T> createState() {
return _ParseLiveListElementWidgetState<T>(loadedData, stream);
return _ParseLiveListElementWidgetState<T>(
loadedData, preLoadedData, stream);
}
}

class _ParseLiveListElementWidgetState<T extends sdk.ParseObject>
extends State<ParseLiveListElementWidget<T>>
with SingleTickerProviderStateMixin {
_ParseLiveListElementWidgetState(
sdk.DataGetter<T> loadedDataGetter, sdk.StreamGetter<T> stream) {
_snapshot =
sdk.ParseLiveListElementSnapshot<T>(loadedData: loadedDataGetter());
_ParseLiveListElementWidgetState(sdk.DataGetter<T> loadedDataGetter,
sdk.DataGetter<T> preLoadedDataGetter, sdk.StreamGetter<T> stream) {
_snapshot = sdk.ParseLiveListElementSnapshot<T>(
loadedData: loadedDataGetter(), preLoadedData: preLoadedDataGetter());
if (stream != null) {
_streamSubscription = stream().listen(
(T data) {
if (widget != null) {
setState(() {
_snapshot = sdk.ParseLiveListElementSnapshot<T>(loadedData: data);
_snapshot = sdk.ParseLiveListElementSnapshot<T>(
loadedData: data, preLoadedData: data);
});
} else {
_snapshot = sdk.ParseLiveListElementSnapshot<T>(loadedData: data);
_snapshot = sdk.ParseLiveListElementSnapshot<T>(
loadedData: data, preLoadedData: data);
}
},
onError: (Object error) {
Expand Down