ParseLiveListElementSnapshot added (#329)

* Created ParseLiveList

* LiveList & LivListBuilder works

* Cleanup

* changed to animated list

* Fix in dataloading

* updated AnimatedList

* Finished Animations & cleanup

* handle reconnect

* Added dispose methodes & renamed classes & cleanup

* cleanup

* Fix animation duration

* added README ParseLiveList section

* Initialized example_livelist

* Update application_constants.dart

* Update .gitignore

* Revert "Update .gitignore"

This reverts commit 4d8982d.

* Update .gitignore

* HotFix: object Update from client

If the client changes the object.
(ParseObject does not get copied)

* Implemented simple example

* Update README.md

* Update main.dart

* Update README.md

* Update README.md

* LiveList - Performance Improvement

This is the change mentioned in #324 (comment)

Requires #326

* LiveList - Performance Improvement

This is the change mentioned in #324 (comment)

Requires #326

* example_livelist: use clientKey

* Changed example_livelist query

In the README I wrote, you can use a field called "show" to hide elements.

* Remove: RemovedItemBuilder

duplicade to ChildBuilder

* removed firstBuild

* ParseLiveListElementSnapshot added

Author: fischerscode

example_livelist/lib/main.dart

@@ -80,31 +80,32 @@ class _MyAppState extends State<MyApp> {
           child: ParseLiveListWidget<ParseObject>(
               query: _queryBuilder,
               duration: const Duration(seconds: 1),
-              childBuilder:
-                  (BuildContext context, bool failed, ParseObject loadedData) {
-                if (failed) {
+              childBuilder: (BuildContext context,
+                  ParseLiveListElementSnapshot<ParseObject> snapshot) {
+                if (snapshot.failed) {
                   return const Text('something went wrong!');
-                } else if (loadedData != null) {
+                } else if (snapshot.hasData) {
                   return ListTile(
                     title: Row(
                       children: <Widget>[
                         Flexible(
-                          child: Text(loadedData.get<int>('order').toString()),
+                          child: Text(
+                              snapshot.loadedData.get<int>('order').toString()),
                           flex: 1,
                         ),
                         Flexible(
                           child: Container(
                             alignment: Alignment.center,
                             child: Text(
-                              loadedData.get<String>('text'),
+                              snapshot.loadedData.get<String>('text'),
                             ),
                           ),
                           flex: 10,
                         ),
                       ],
                     ),
                     onLongPress: () {
-                      objectFormKey.currentState.setObject(loadedData);
+                      objectFormKey.currentState.setObject(snapshot.loadedData);
                     },
                   );
                 } else {

lib/src/utils/parse_live_list.dart

@@ -207,9 +207,10 @@ class ParseLiveList<T extends ParseObject> {
               keyVarObjectId, _list[index].object.get<String>(keyVarObjectId))
           ..setLimit(1);
         final ParseResponse response = await queryBuilder.query();
-        if (response.success) {
+        if (response.success && response.results != null) {
           _list[index].object = response.results.first;
         } else {
+          _list[index].object = null;
           throw response.error;
         }
       }
@@ -293,12 +294,20 @@ class ParseLiveListDeleteEvent<T extends ParseObject>
   ParseLiveListDeleteEvent(int index, T object) : super(index, object);
 }
 
-typedef Stream<T> StreamGetter<T extends ParseObject>();
-typedef T DataGetter<T extends ParseObject>();
-typedef Widget ChildBuilder<T extends ParseObject>(
-    BuildContext context, bool failed, T loadedData);
-typedef Widget RemovedItemBuilder<T extends ParseObject>(
-    BuildContext context, int index, T oldObject);
+typedef StreamGetter<T extends ParseObject> = Stream<T> Function();
+typedef DataGetter<T extends ParseObject> = T Function();
+typedef ChildBuilder<T extends ParseObject> = Widget Function(
+    BuildContext context, ParseLiveListElementSnapshot<T> snapshot);
+
+class ParseLiveListElementSnapshot<T extends ParseObject> {
+  ParseLiveListElementSnapshot({this.loadedData, this.error});
+
+  final T loadedData;
+  final ParseError error;
+
+  bool get hasData => loadedData != null;
+  bool get failed => error != null;
+}
 
 class ParseLiveListWidget<T extends ParseObject> extends StatefulWidget {
   const ParseLiveListWidget(
@@ -329,8 +338,8 @@ class ParseLiveListWidget<T extends ParseObject> extends StatefulWidget {
   final bool reverse;
   final bool shrinkWrap;
 
-  final ChildBuilder childBuilder;
-  final RemovedItemBuilder<T> removedItemBuilder;
+  final ChildBuilder<T> childBuilder;
+  final ChildBuilder<T> removedItemBuilder;
 
   @override
   _ParseLiveListWidgetState<T> createState() =>
@@ -392,7 +401,7 @@ class _ParseLiveListWidgetState<T extends ParseObject>
   ParseLiveList<T> _liveList;
   final GlobalKey<AnimatedListState> _animatedListKey =
       GlobalKey<AnimatedListState>();
-  final RemovedItemBuilder<T> removedItemBuilder;
+  final ChildBuilder<T> removedItemBuilder;
 
   @override
   Widget build(BuildContext context) {
@@ -448,7 +457,7 @@ class ParseLiveListElementWidget<T extends ParseObject> extends StatefulWidget {
   final DataGetter<T> loadedData;
   final Animation<double> sizeFactor;
   final Duration duration;
-  final ChildBuilder childBuilder;
+  final ChildBuilder<T> childBuilder;
 
   @override
   _ParseLiveListElementWidgetState<T> createState() {
@@ -461,23 +470,38 @@ class _ParseLiveListElementWidgetState<T extends ParseObject>
     with SingleTickerProviderStateMixin {
   _ParseLiveListElementWidgetState(
       DataGetter<T> loadedDataGetter, StreamGetter<T> stream) {
-    loadedData = loadedDataGetter();
+//    loadedData = loadedDataGetter();
+    _snapshot = ParseLiveListElementSnapshot<T>(loadedData: loadedDataGetter());
     if (stream != null) {
-      _streamSubscription = stream().listen((T data) {
-        if (widget != null) {
-          setState(() {
-            loadedData = data;
-          });
-        } else {
-          loadedData = data;
-        }
-      });
+      _streamSubscription = stream().listen(
+        (T data) {
+          if (widget != null) {
+            setState(() {
+              _snapshot = ParseLiveListElementSnapshot<T>(loadedData: data);
+            });
+          } else {
+            _snapshot = ParseLiveListElementSnapshot<T>(loadedData: data);
+          }
+        },
+        onError: (Object error) {
+          if (error is ParseError) {
+            if (widget != null) {
+              setState(() {
+                _snapshot = ParseLiveListElementSnapshot<T>(error: error);
+              });
+            } else {
+              _snapshot = ParseLiveListElementSnapshot<T>(error: error);
+            }
+          }
+        },
+        cancelOnError: false,
+      );
     }
   }
-  T loadedData;
-  bool failed = false;
+
+  ParseLiveListElementSnapshot<T> _snapshot;
+
   StreamSubscription<T> _streamSubscription;
-  bool firstBuild = true;
 
   @override
   void dispose() {
@@ -493,10 +517,9 @@ class _ParseLiveListElementWidgetState<T extends ParseObject>
       child: AnimatedSize(
         duration: widget.duration,
         vsync: this,
-        child: widget.childBuilder(context, failed, loadedData),
+        child: widget.childBuilder(context, _snapshot),
       ),
     );
-    firstBuild = false;
     return result;
   }
 }