Flutter Question posted in
The official Flutter documentation can be found here.

Flutter – DropdownButton with static list is giving an error

I am trying to add a dropdownbutton to my flutter app. The dropdown will have a static list of items.

This is the code I am trying to use:

DropdownButton<String>(
                  hint: const Text('Please choose transaction status'),
                  value: _trxnStatus,
                  onChanged: (_value) {
                    setState(() {
                      _trxnStatus = _value;
                    });
                  },
                  items: <String>[
                    'Select Status',
                    'Prospect',
                    'Listed',
                    'Under Contract',
                    'On Hold',
                    'Closed',
                    'Archived'
                  ].map<DropdownMenuItem<String>>((String _value) {
                    return DropdownMenuItem<String>(
                      value: _value,
                      child: Text(_value),
                    );
                  }).toList(),
                ),

When I run this code, I am getting this error (sorry but it won’t let me copy the text):
error message

Why am I getting this error?

Thanks for your help.

Tags:

2

Answers


  1. 0

    From the given code, everything seems normal except for the _trxnStatus state variable.

    The exception pretty much straightly says, you must need EXACTLY one DropdownMenuItem matching the value of _trxnStatus. Since you’re using the list of all possible values and mapping it to DropdownMenuItem the only possible way to get to this crash-site, you’re initializing _trxnStatus to a different value at the beginning.

    Try defining the _trxnStatus as nullable, and leave it null at first.

    String? _trxnStatus;

    Or set the initial value to a value inside the list.

    String? _trxnStatus = "Select Status";

    Hope this helps.

    Login or Signup to reply.
  2. 0

    Try below code hope it’s help to you.

    List declaration:

    List<String> list = <String>[
  'Select Status',
  'Prospect',
  'Listed',
  'Under Contract',
  'On Hold',
  'Closed',
  'Archived'
];

    variable declartion:

    String dropdownValue = list.first;

    Dropdown Widget UI:

    DropdownButton<String>(
  hint: const Text('Please choose transaction status'),
  value: dropdownValue,
  onChanged: (value) {
    setState(() {
      dropdownValue = value!;
      print('Selected Value = $dropdownValue');
    });
  },
  items: list.map<DropdownMenuItem<String>>((value) {
    return DropdownMenuItem<String>(
      value: value,
      child: Text(value),
    );
  }).toList(),
),

    Read more about DropdownButton

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search