DropDown Menu not working

[Mark Valeriani]

I am trying to make a form and have a dropdown menu in it but it seems to not be working. For reference: 

    myGroups - passed into the widget as an object of Groups

    groupSelected - an object Groups

 DropdownButtonFormField<Groups>(

                items: myGroups

                    .map((label) => DropdownMenuItem(

                          child: Text(label.groupName),

                          value: label,

                        ))

                    .toList(),

                hint: Text('Group'),

                value: groupSelected,

                onChanged: (value) {

                  setState(() {

                    groupSelected = value;

                  });

                },

              ),

I keep getting an error saying 

The following assertion was thrown building Builder(dirty, dependencies: [_FocusMarker]):

There should be exactly one item with [DropdownButton]'s value: Instance of 'Groups'.

Either zero or 2 or more [DropdownMenuItem]s were detected with the same value

'package:flutter/src/material/dropdown.dart':

Failed assertion: line 855 pos 15: 'items == null || items.isEmpty || value == null ||

              items.where((DropdownMenuItem<T> item) {

                return item.value == value;

              }).length == 1'

[Suzuki Tomohiro]

> There should be exactly one item with [DropdownButton]'s value

What are the values in your "myGroups" variable? Are there any duplicates?

--
You received this message because you are subscribed to the Google Groups "Flutter Development (flutter-dev)" group.
To unsubscribe from this group and stop receiving emails from it, send an email to flutter-dev...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/flutter-dev/7a153923-3790-4449-9797-04f1a750f055n%40googlegroups.com.

[Mark Valeriani]

Nope just one value to test the functioning. Just a group, no duplicates.

[Suzuki Tomohiro]

Good. That’s simple. Can you add a breakpoint and see why the assertion fails?

Failed assertion: line 855 pos 15: 'items == null || items.isEmpty || value == null ||

              items.where((DropdownMenuItem<T> item) {

                return item.value == value;

              }).length == 1'

To view this discussion on the web visit https://groups.google.com/d/msgid/flutter-dev/46e3b3dd-726e-4dae-accb-9dd781bcee9bn%40googlegroups.com.

[Mark Valeriani]

I tried putting a breakpoint and didn't get anything back. To be honest not super familiar with debugging using your IDE  

[Suzuki Tomohiro]

Learn this video

https://youtu.be/O0UvfT5bUPg

Android Studio also works in a similar manner.

To view this discussion on the web visit https://groups.google.com/d/msgid/flutter-dev/0f1bdeab-031a-4b11-8ca7-e28647c13031n%40googlegroups.com.