dart

问题 I have an idiot question. is it possible to run the build runner in an application compiled for dynamic code generation? 回答1: In a Flutter application, no. Flutter apps neither have the ability to dynamically evaluate Dart code, nor do they have access to the tools needed to parse and generate source code. 来源： https://stackoverflow.com/questions/61015321/run-flutter-builder-runner-in-compiled-app

问题 I am trying to save a List of List but I don't know how to do that. So I have List<List> _randList = new List(); 回答1: See, there is no way that we can use Shared Preferences in order store List<List<String>> . However, we can always use a workaround. Since, we already that we can store the List<String> only in the Shared Preferences, it is best to store the nested lists in the form of String , like below List<String> _arr = ["['a', 'b', 'c'], ['d', 'e', 'f']"]; In this way, you will be having

问题 I want to cast a Map<String, dynamic> to Map<String, List<String>> . I have tried the following in Flutter: Map<String, dynamic> dynamicMap = { 'a': ['1', '2', '3'], 'b': ['1', '2', '3'], 'c': ['1', '2', '3'], }; Map<String, List<String>> typedMap = dynamicMap; But get the following error: type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'Map<String, List<String>>' I then tried: Map<String, List<String>> typedMap = dynamicMap.cast<String, List<String>>(); which seems to

问题 I have a function in firebase that is intended to get all documents in a collection called history and add it to a list intended to be returned. The problem is, and I think this is because .listen() is async, the list returned is always empty. I know the data is queried correctly because I can print the doc in the forEach function, but adding to a list outside doesn't work. By the way, myStream is a snapshot of the history collection in FireStore. Does my function need to be a Future? How can

问题 Is there some way to draw a dashed arc in Flutter? At the moment I'm using canvas.drawArc but I don't know how to get the correct result. canvas.drawArc( rectangle, startAngle, fullArcRadius, false, Paint() ..color = Colors.black ..strokeCap = StrokeCap.round ..style = PaintingStyle.stroke ..strokeWidth = 2.0, ); dashed-arc 回答1: Unfortunately, flutter doesn't handle dashes all that well. There is a plugin that helps with it though: path_drawing Using that, you can draw any path dashed simply

问题 Edit: i know, always call the first element on list, it isnt the point. i want to call numbers[0] func. and it regenerate new int.actually codes are not same which mine, i have a custom class which based on functions with random int and i need to use list of my custom class , so if i use func in list it will be awesome, how can i make new numbers list each time. when app start list regenerated, but i want when i call the list, it will regenerated i want to print new int for each print but it

问题 How to update data of isVerified (Boolean) field. Personal Info is Map contains address and then isVerified. 回答1: To update isVerified , you have to do the following: Firestore.instance.collection("collection Name").document("documentId").updateData({ "Personal Info.address.isVerified": true, }).then((_) { print("success!"); }); 回答2: Since you did not provide your collection or document name I would just form one So lets assume every time we click a button the value should be changed to true

问题 I am using a stream builder to detect if user logged in or not. return StreamBuilder<User>( stream: AuthService().user, builder: (context, snapshot) { if (snapshot.hasData) return SectionWrapper(); else return Authentication(); }); and this is the stream I am using Stream<User> get user { return _auth.onAuthStateChanged.map(_userFromFirebaseUser); } //create user object based on firebase user User _userFromFirebaseUser(FirebaseUser user) { return user != null ? User(uid: user.uid, email: user

问题 I am using a stream builder to detect if user logged in or not. return StreamBuilder<User>( stream: AuthService().user, builder: (context, snapshot) { if (snapshot.hasData) return SectionWrapper(); else return Authentication(); }); and this is the stream I am using Stream<User> get user { return _auth.onAuthStateChanged.map(_userFromFirebaseUser); } //create user object based on firebase user User _userFromFirebaseUser(FirebaseUser user) { return user != null ? User(uid: user.uid, email: user

问题 I'm trying to use color , fontWeight and fontFamily with style: style.copyWith , the custom font I'm trying to use is Vonique , I've imported it like so into pubspec.yaml fonts: - family: Vonique fonts: - assets: fonts/Vonique-64-Bold-Italic.ttf - assets: fonts/Vonique-64-Italic.ttf - assets: fonts/Vonique-64-Bold.ttf - assets: fonts/Vonique-64.ttf Is this the correct way to import it? I've tried it both was with '' and without '', still doesn't change the text font. Text('Login', style: