如何解决在onPress颤动之前，如何根据条件更改listView负载上IconButton的颜色？
我有ListView个帖子，每行或每个帖子都有IconButton个。现在用户可以喜欢任何帖子。我需要检查用户是否喜欢某个帖子，并且该帖子的IconButton会是蓝色的。用户不喜欢的帖子，IconButton颜色为灰色。当帖子列表正在加载时，我需要检查它。
列表：
children: <Widget> [
Row(
children: <Widget>[
new IconButton(
icon: new Icon(Icons.thumb_up),// documentId = list[index].id;
// want to get documentId in this way from here and pass this documentId to the method like checkPostLikedOrNot(documentId);
// checkFeedLikedOrNot(documentId );
// want to call this method here and check the conditon
color:(isPressed) ? Color(0xff007397) : Color(0xff9A9A9A),onPressed: (){
print(widget.userId); // userId
documentId = list[index].id;
_counter = list[index].data()["like_count"];
_incrementCounter(); // updating table with userId in this method
},),],检查方法：
checkFeedLikedOrNot(documentId) async{
DocumentReference docRef = FirebaseFirestore.instance.collection('post').doc(documentId);
DocumentSnapshot docSnapshot = await docRef.get();
List likedUser = docSnapshot.data()['liked_user_id'];
if(likedUser.contains(widget.userId) == true){
print('user already exist=='+ widget.userId);
//color will be blue
}else{
//color will be grey
}
}
构建ListView
return ListView.builder(
shrinkWrap: true,primary: false,itemCount: list.length,itemBuilder:(context,index) {
print(index);
return Card(
elevation: 5,shape: Border(bottom: BorderSide(color: Colors.lightBlue,width: 5)),child: Column(
children: <Widget> [
ListTile(
我该怎么做？
解决方法
关于提高安全性的说明：您的API应该具有一种方法来检查用户是否喜欢userId和postId的帖子（或使用userId获取给定Future<bool>的所有喜欢的帖子的ID）分页）。这不是让所有喜欢该帖子的用户的好方法。
您可以使用FutureBuilder。
检查方法应返回 Future<bool> checkFeedLikedOrNot(documentId) async {
DocumentReference docRef = FirebaseFirestore.instance.collection('post').doc(documentId);
DocumentSnapshot docSnapshot = await docRef.get();
List likedUser = docSnapshot.data()['liked_user_id'];
return likedUser.contains(widget.userId);
}
FutureBuilder然后您可以使用Icon来获取 Widget getIcon(documentId) {
return FutureBuilder<bool>(
builder: (BuildContext context,AsyncSnapshot<bool> snapshot) {
Color color = Colors.grey; // set proper default color
if (snapshot != null && snapshot.connectionState == ConnectionState.done &&
snapshot.hasData != null) {
color = Colors.blue; // set proper "liked" color
}
return Icon(
Icons.thumb_up,color: color,);
},future: checkFeedLikedOrNot(documentId),);
}
IconButton并在new IconButton(
icon: getIcon(list[index].id),// documentId = list[index].id;
// want to get documentId in this way from here and pass this documentId to the method like checkPostLikedOrNot(documentId);
// checkFeedLikedOrNot(documentId );
// want to call this method here and check the conditon
color:(isPressed) ? Color(0xff007397) : Color(0xff9A9A9A),onPressed: (){
print(widget.userId); // userId
documentId = list[index].id;
_counter = list[index].data()["like_count"];
_incrementCounter(); // updating table with userId in this method
},),
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
//Your task it will execute at 1 time only...
onBackPressed();{
if (webview.isFocused() && webview.canGoBack()) {
webview.goBack();
}
if(mRewardedVideoAd.isLoaded()) {
mRewardedVideoAd.show();
}
}
}
},5000);//5 seconds delay and you can change the delay time...
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