dart - 更改 StreamController 后按钮保持禁用状态.broadcast() 到 BehaviorSubject()
问题描述
我使用 Streams 和 rxdart 进行表单验证。当我使用StreamController<String>.broadcast()
时,按钮启用-禁用逻辑工作正常。
BehaviorSubject<String>()
即使逻辑正确,将其更改为按钮仍处于禁用状态。
块飞镖
import 'dart:async';
import 'package:login_validation_with_bloc/blocs/validator.dart';
import 'package:rxdart/rxdart.dart';
class Bloc with Validator {
final _emailController = StreamController<String>.broadcast();
final _passwordController = StreamController<String>.broadcast();
Stream<String> get email => _emailController.stream.transform(validateEmail);
Stream<String> get password =>
_passwordController.stream.transform(validatePassword);
Stream<bool> get validForm =>
Observable.combineLatest2(email, password, (e, p) => true);
Function(String) get changeEmail => _emailController.sink.add;
Function(String) get changePassword => _passwordController.sink.add;
dispose() {
_emailController.close();
_passwordController.close();
}
}
final bloc = Bloc();
home.dart,两个文本字段和提交按钮
Widget emailTextField(context, Bloc bloc) => StreamBuilder(
stream: bloc.email,
builder: (context, snapshot) => TextField(
decoration: InputDecoration(
labelText: "Email",
hintText: "Enter your email address",
errorText: snapshot.error,
border: UnderlineInputBorder()),
keyboardType: TextInputType.emailAddress,
onChanged: bloc.changeEmail,
),
);
Widget passwordTextField(context, Bloc bloc) => StreamBuilder(
stream: bloc.password,
builder: (context, snapshot) => TextField(
decoration: InputDecoration(
labelText: "Password",
hintText: "Enter your password",
errorText: snapshot.error,
border: UnderlineInputBorder()),
keyboardType: TextInputType.text,
obscureText: true,
onChanged: bloc.changePassword,
),
);
Widget submitButton(context, Bloc bloc) => StreamBuilder(
stream: bloc.validForm,
builder: (context, snapshot) {
return Container(
child: RaisedButton(
color: Colors.blue,
disabledColor: Colors.grey,
textColor: Colors.white,
disabledTextColor: Colors.white70,
onPressed: snapshot.hasData && !snapshot.hasError
? () {
print("Submit button pressed");
}
: null,
elevation: 5,
disabledElevation: 0,
child: Text("Submit"),
),
);
},
);
变化
在 bloc.dart
final _emailController = BehaviorSubject<String>();
final _passwordController = BehaviorSubject<String>();
submit() {
final validEmail = _emailController.value;
final validPassword = _passwordController.value;
print("\n\tEmail: $validEmail\n\tPassword: $validPassword");
}
在 home.dart
snapshot.hasData && !snapshot.hasError ? bloc.submit() : null,
我希望当逻辑正确时按钮应该保持启用状态,并且除非按下按钮,否则不应调用该方法
解决方案
在 home.dart 中:
改变这个:
snapshot.hasData && !snapshot.hasError ? bloc.submit() : null,
至此
snapshot.hasData && !snapshot.hasError ? bloc.submit : null,
说明:
with bloc.submit
you 指的是方法,with bloc.submit()
you 指的是该方法的返回值。
您所做的是您指的是该方法的返回值,并且由于您没有返回该方法刚刚执行的任何内容,但是由于返回的值为 null,因此按钮仍处于禁用状态。
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