Flutter - DropdownButton overflow

The easiest solution is to add the isExpanded property to true in DropdownButton

For example:

DropdownButton(
  isExpanded: true, //Adding this property, does the magic
  items: [
    DropdownMenuItem(
      child: Text(
          "Some large text that needs to be wrapped or ellipsized",
          overflow: TextOverflow.ellipsis),
    ),
    DropdownMenuItem(
      child: Text(
          "This is another large text that needs to be wrapped or ellipsized",
          overflow: TextOverflow.ellipsis),
    ),
    DropdownMenuItem(
      child: Text(
          "And one more large text that needs to be wrapped or ellipsized",
          overflow: TextOverflow.ellipsis),
    )
  ],
  onChanged: (val) {
    //print(val);
  },
),

I managed to solve the issue by wrapping the child of DropdownMenuItem in a SizedBox and by giving sizedBox a fixed width which will not overflow the UI and still look good.

eg.

                   new DropdownMenuItem<String>(
                      value: value,
                      child:  new SizedBox(
                        width: 200.0,
                        child: new Text('Long text with ${value} ')
                      ),
                    )

Try using isExpanded: true,

It will automatically extend the text to new line

DropdownButton(
     isExpanded: true, //Add this property
     items: [
          DropdownMenuItem(
              child: Text("Your Text Here", 
              overflow: TextOverflow.ellipsis),
          ),
}),

Refer below image

There was not enough space to text in a line so continued with next line

None of the above solves this problem properly.

please try FittedBox as documented here

just wrap your DropdownMenuItem's child like this

DropdownMenuItem<MyDropdownContentClass>(
            child: FittedBox(
              child: Text("dropdown item display"),
              fit: BoxFit.contain,
            ),
          );

it will automatically resize the whole widget during paint, which is your Text().

In order for this to work if you are using a row, you have to set both the row child to Expanded, and the DropdownButton isExpanded property:

Row(
    children: <Widget>[
      Expanded(
        child: DropdownButton<String>(
          isExpanded: true, 
          value: _selectedLanguageNative,
          items: list,
          hint: Text(LanguageLocal.getDisplayLanguage(
              Localizations.localeOf(context).languageCode)["name"]),
          onChanged: (String value) {
            print(value);
            setState(() {
              _selectedLanguageNative = value;
            });
          },
        ),
      ),
    ],
  ),

Elaborating on ganapat answer you can set up the list this way:

final dropdownItems = _list
        .map((String item) => new DropdownMenuItem<String>(
              value: item,
              child: new SizedBox(width: 200.0, child: new Text(item)),
            ))
        .toList();

I struggled with this and eventually found a perfectly good solution to the problem that @Dah raises. It is hinted at in the Github issue Look at Sep 18, 2019: to make use of the selectedItemBuilder property of the DropDownButton. There is also a good working example here Flutter Docs. I'm including a segment of my code which simply puts ellipsis in place of long text in the dropdownbutton when it is closed. It does his by making use of the returned Text() widget of the selectedItemBuilder, which allows the overflow property to set the ellipsis:

child: DropdownButton<String>(
        isExpanded: true,
        hint: Text('Select Faculty'),
        value: selectedFaculty,
        underline: Container(
          height: 0,
        ),
        onChanged: (String value) async {
          selectedFaculty = value;
        },
        selectedItemBuilder: (BuildContext context) {
          return dropFaculty.map<Widget>((String text) {
            return Text(
              text,
              overflow: TextOverflow.ellipsis,
            );
          }).toList();
        },
        items: disableKeyFields || selectedInstitution == null
            ? null
            : dropFaculty.map((String faculty) {
                return DropdownMenuItem<String>(
                  value: faculty,
                  child: Text(
                    faculty,
                    style: TextStyle(color: Colors.black),
                  ),
                );
              }).toList(),
      ),

Thanks for brianegan's answer.

After step 3, look at the class _DropdownMenuRouteLayout:

  @override
  BoxConstraints getConstraintsForChild(BoxConstraints constraints) {
    // The maximum height of a simple menu should be one or more rows less than
    // the view height. This ensures a tappable area outside of the simple menu
    // with which to dismiss the menu.
    //   -- https://material.io/design/components/menus.html#usage
    final double maxHeight =
        math.max(0.0, constraints.maxHeight - 2 * _kMenuItemHeight);
    // The width of a menu should be at most the view width. This ensures that
    // the menu does not extend past the left and right edges of the screen.
    final double width = math.min(constraints.maxWidth, buttonRect.width);
    return BoxConstraints(
      minWidth: width,
      maxWidth: width,
      minHeight: 0.0,
      maxHeight: maxHeight,
    );
  }

You can implement the 'maxWith' in your own way.

An easy and elegant solution that allows you to put the entire text inside the selection is to use BoxFit in combination with isExpanded set to true like this:

DropdownButton(
  isExpanded: true, //Magic #1
  items: [
    DropdownMenuItem(
      child: FittedBox(fit: BoxFit.scaleDown, //Magic #2
        child: Text(
            "Some large text that needs to be wrapped instead ellipsized"),
      ),
    ),
    // The rest of Items
],

For the FittedBox to work correctly you must ensure that the DropDownButton is wrapped in a container with a certain width that allows the function to know in what measurements it should display the text.