flutter - 使用流/ block 从列表中的文本字段中设置值

Question

使用流/块时，我在为文本字段设置值时遇到问题。基本上，我有一个文本字段，单击时我想要一个弹出对话框来提供要选择的值列表。当用户选择一个值时，应在文本字段中设置该值。当使用常规文本字段时，我知道我可以使用 textfield.text = value 但是当使用流/块时是不同的。我不知道如何使用它。

这是我的流代码

import 'dart:async';
import 'validators.dart';
import 'package:rxdart/rxdart.dart';


class Bloc extends Object with Validators {

  final amountController = BehaviorSubject<String>();
  final frequencyController = BehaviorSubject<String>();
  final datePaidController = BehaviorSubject<String>();
  final categoryController = BehaviorSubject<String>();
  final depositToController = BehaviorSubject<String>();
  final descriptionController = BehaviorSubject<String>();

  // Add data to stream
  Stream<String> get amount => amountController.stream.transform(validateAmount);
  Stream<String> get frequency =>
      frequencyController.stream.transform(validateEmpty);
  Stream<String> get datePaid =>
      datePaidController.stream.transform(validateEmpty);
  Stream<String> get category =>
      categoryController.stream.transform(validateEmpty);
  Stream<String> get deposit =>
      depositToController.stream.transform(validateEmpty);
  Stream<String> get description =>
      descriptionController.stream.transform(validateEmpty);
/*
  Stream<bool> get submitValid =>
      Observable.combineLatest6(amount, frequency, datePaid, category, deposit,
          description, (a,b,c,d,e,f) => true);
*/

  // change data
  Function(String) get changeAmount => amountController.sink.add;
  Function(String) get changeFrequency => frequencyController.sink.add;
  Function(String) get changeDatePaid => datePaidController.sink.add;
  Function(String) get changeCategory => categoryController.sink.add;
  Function(String) get changeDepositTo => depositToController.sink.add;
  Function(String) get changeDescription => descriptionController.sink.add;

  submit() {
    final validAmount = amountController.value;
    final validFrequency = frequencyController.value;
    final validDatePaid = datePaidController.value;
    final validCategory = categoryController.value;
    final validDepositTo = depositToController.value;
    final validDescription = descriptionController.value;

 //   print('Email is $validEmail, and password is $validPassword');
  }

  dispose() {
    amountController.close();
    frequencyController.close();
    datePaidController.close();
    categoryController.close();
    depositToController.close();
    descriptionController.close();
  }
}

我的文本字段代码(与上面的不同)

 final bloc = Provider.of(context);

 return StreamBuilder(
      stream: bloc.amount,
      builder: (context, snapshot) {
        return TextField(
          onChanged: bloc.changeAmount,
          keyboardType: TextInputType.text,
          decoration: InputDecoration(
            hintText: 'Income Amount',
            // labelText: 'Email Address',
            errorText: snapshot.error,
            prefixIcon: Icon(Icons.attach_money),
            suffix: IconButton(
              icon: Icon(Icons.arrow_right),
              onPressed: () => {

              showDialog(
                 context: context,
                 builder: (BuildContext context) {
                   // return object of type Dialog
                  return AlertDialog(
                    title: new Text("Alert Dialog title"),
                  content: new Text("Alert Dialog body"),
                  actions: <Widget>[
                    // usually list of items to choose from

              ),
              ],
              );
              },
              )
              },

            ),
          ),
        );
      },
    );

如果您查看文本字段代码，则文本字段上的图标有 onPressed 函数。按下时，应出现一个对话框供用户选择一个值。一旦选择了一个值，我想用该值设置文本字段。我正在使用流/块，但我不知道该怎么做，因为文本 Controller 在 Bloc 类中，而文本字段代码是另一个类。当用户从弹出列表中选择时，有人可以帮助如何设置文本字段值吗？提前致谢

Answer 1

使用 TextEditingController .
它将允许您在文本字段中处理和设置文本值。
你可以这样使用它:

final _controller = TextEditingController();

在文本字段中，分配 _controller :

TextField(
          controller: _controller,
          //everything else should be same as before
),

当需要使用新值更新文本字段时，您可以执行以下操作:

_controller.text = newAmountFromStream;