Dart 2 is changing the Dart language in many ways, some of which are not backward-compatible.
Questions tagged [dart-2]
60 questions
154
votes
8 answers
What is the correct way to add date picker in flutter app?
In my app I am creating signup page where I need to add DOB. I want to add date picker in that but I am not getting correct way to do this.
Code Hunter
- 10,075
- 23
- 72
- 102
53
votes
8 answers
The argument type 'Object' can't be assigned to the parameter type 'ImageProvider
I just updated to Dart2 and Flutter sdk: '>=2.12.0 <3.0.0' and now this if statement breaks:
decoration: new BoxDecoration(
shape: BoxShape.circle,
color: Colors.blueAccent,
border: Border.all(
…
JoergP
- 1,349
- 2
- 13
- 28
33
votes
11 answers
pub global activate command - $HOME/.pub-cache/bin not on path
I was trying to install dart2 recently, but when I try to install pub global activate stagehand, it comes with a warning.
Warning: Pub installs executables into $HOME/.pub-cache/bin, which is not on your path.
You can fix that by adding this to…
Kevin
- 477
- 1
- 5
- 13
28
votes
2 answers
How do I declare 64bit unsigned int in dart/flutter?
For an app, I need a 64bit unsigned int. Looking at dart documentation I did not see how to exactly go about declaring one.
Can anyone tell me how this is done? I will use this "64bit unsigned int" in bitwise operation.
Ragas
- 3,005
- 6
- 25
- 42
16
votes
7 answers
Cannot focus on TextField in new page after navigating in Flutter
For some reason, I cannot focus on a TextField after on the next page after navigating. The keyboard would automatically dismiss when the TextField is selected. If I set autofocus: true on the TextField, then the keyboard will infinitely popup and…
Pybanana
- 351
- 1
- 2
- 6
12
votes
4 answers
Upload & fetch media files from AWS S3 in Flutter
My flutter app is using firebase as a backend but I need to store media files (photos & videos) in my s3 bucket. The mission is to upload the media retrieved from the image picker into s3 & get back the url, which can then be stored as a string in…
Endemic
- 370
- 1
- 2
- 15
12
votes
2 answers
Bidirectional communication with isolates in Dart 2
I'm trying isolates and I'm wondering how could I spawn some of them doing heavy computations that, when the root Isolate ask them for their current computing value they respond it, "on demand".
As far as I know, the only object that can be used as…
Nico Rodsevich
- 2,393
- 2
- 22
- 32
11
votes
2 answers
Callback with generic type parameter in Dart
I'm trying to define a callback function that needs to accept a generic parameter and return a value of the same type. Keep in mind that the following example is an oversimplified version of what I actually need.
final T Function(T value) self =…
skreborn
- 2,133
- 2
- 16
- 27
11
votes
1 answer
How to typedef a generic function?
I have a generic static method that looks like this:
static build() {
return (GenericClass param) => MyClass(param);
}
So far I have tried:
typedef F = MyClass Function(GenericClass param);
but it says that:
The return type…
arielnmz
- 8,354
- 9
- 38
- 66
9
votes
3 answers
Flutter NetworkImage handle 403 error
In my Flutter mobile app while loading profile image of users through NetworkImage(), I am getting 403 status code in response.
How can I handle this by displaying an Image from my assets folder in case of 403 status code or if image URL is broken…
Thanthu
- 4,399
- 34
- 43
7
votes
1 answer
Null-aware function call?
Dart has some null-aware operators, i.e. it is possible to do
var obj;
obj?.foo(); // foo is only called if obj != null.
Is this also possible for functions that are stored or passed to variables? The usual pattern is
typedef void SomeFunc();
void…
Eiko
- 25,601
- 15
- 56
- 71
7
votes
2 answers
When is const optional in Dart 2?
In Dart Object() constructor is declared as const so:
identical(const Object(), const Object()); //true
I know that in Dart 2 the keyword const is optional and I thought that the previous statement was equivalent to:
identical(Object(), Object());…
user1756508
- 109
- 5
5
votes
2 answers
What is the difference among .cast() and List.from() and List.castFrom()
List foo -> List bar
I can use three method
1.List bar = foo.cast()
2.List bar = List.castFrom(foo)
3.List bar = List.from(foo)
What is the difference?
Taz
- 1,737
- 1
- 15
- 30
5
votes
0 answers
Dart2JS Cannot get async code to run when converted from Dart to Javascript
main() async {
print('Hello World');
await getAsyncString().then((hello) => print(hello));
}
Future getAsyncString() async {
return 'Hello Async World';
}
This is my code example, index.dart. It is in my web folder.
I run webdev…
John Franke
- 1,444
- 19
- 23
5
votes
5 answers
Could not find a generator for route "home-page" in the _MaterialAppState
I am getting exception when I trying to navigate from one view to another in flutter app.
I/flutter ( 2199): ══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
I/flutter ( 2199): The following…
Code Hunter
- 10,075
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- 102