Flutter: Selected value in dropdown list

Question

The initial value in the dialog box doesn't change when I select an item. Here is the code for the dropdown list:

void _buildStatusDialog(String documentID) {
String _selectedText = "SDD";
showDialog<void>(
    context: context,
    builder: (BuildContext context) {
      return AlertDialog(
        title: Text("Status Update"),
        content: new DropdownButton<String>(
          hint: Text("Status"),
          value: _selectedText,
          items: <String>['SDD', 'Meeting', 'Home', 'Space']
              .map((String value) {
            return new DropdownMenuItem<String>(
              value: value,
              child: new Text(value),
            );
          }).toList(),
          onChanged: (String val) {
            _selectedText = val;
            setState(() {
              _selectedText = val;
            });
          },
        ),
        actions: <Widget>[
          FlatButton(
            child: Text("UPDATE"),
            onPressed: () {
              .....
            },
          ),
        ],
      );
    });

}

How do I update the "hint" or display the selected item?

Your setState call is updating the widget that built the dialog, not the dialog. Note that showDialog doesn't get called again. You need to replace your dialog with your own StatefulWidget — Jonah Williams
– Jonah Williams, Commented Jul 24, 2018 at 3:04
Is it possible to achieve this without creating another StatefulWidget? — Ny Regency
– Ny Regency, Commented Jul 24, 2018 at 3:25
no, you need to create a new Element which setState can mark dirty. Otherwise there is no way to update the widget besides closing/opening the dialog — Jonah Williams
– Jonah Williams, Commented Jul 24, 2018 at 3:27

Mahesh Jamdade · Accepted Answer · 2020-09-06 09:26:04Z

Using @Jonah Williams's tip in the comments I came up with the following working example to a similar problem that I had:

import 'package:flutter/material.dart';

class StatusDialog extends StatefulWidget {

  @override
  State<StatefulWidget> createState() {
    return StatusDialogState();
  }
}

class StatusDialogState extends State<StatusDialog> {
  String _selectedText = "SSD";

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: Text("Status Update"),
      content: new DropdownButton<String>(
        hint: Text("Status"),
        value: _selectedText,
        items: <String>['SDD', 'Meeting', 'Home', 'Space']
            .map((String value) {
          return new DropdownMenuItem<String>(
            value: value,
            child: new Text(value),
          );
        }).toList(),
        onChanged: (String val) {
          setState(() {
            _selectedText = val;
          });
        },
      ),
      actions: <Widget>[
        FlatButton(
          child: Text("UPDATE"),
          onPressed: () {
            //.....
          },
        ),
      ],
    );
  }
}

void _buildStatusDialog(String documentID) {
  showDialog<void>(
    context: context,
    builder: (BuildContext context) {
      return StatusDialog();
    }
  );
}

Then you just need to add some logic to obtain _selectedText from StatusDialog - probably using a callback.

Majd AL-Shalash · Accepted Answer · 2023-09-25 13:04:15Z

0

add this line isExpanded: true, it will expand the arrow to the right of the container so the code will be like this:

return DropdownMenuItem<String>(
  value: value,
  child: Text(value),
  isExpanded: true,
);

edited Sep 25, 2023 at 13:04

Majd AL-Shalash

851 silver badge6 bronze badges

answered Feb 15, 2019 at 1:46

Rami Ahmed Sadek

251 bronze badge

1 Comment

AXE Over a year ago

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