I am trying to get the DateTime to appear in a flutter/Dart project and it is not working. For my other selections I am using a TextFormField but when I try to put the dropdown in a box decoration it gives me an error. I am new to Flutter/Dart so I am wondering what I am doing wrong and is there a better more efficient way to write it?

```
//some other code
...    
TextFormField(
                  decoration: InputDecoration(
                    labelText: 'Course Name',
                    contentPadding:
                        EdgeInsets.symmetric(vertical: 10.0, horizontal: 20.0),
                    border: OutlineInputBorder(
                      borderRadius: BorderRadius.all(Radius.circular(32.0)),
                    ),
                    enabledBorder: OutlineInputBorder(
                      borderSide: BorderSide(color: Colors.blueAccent, width: 1.0),
                      borderRadius: BorderRadius.all(Radius.circular(32.0)),
                    ),
                    focusedBorder: OutlineInputBorder(
                      borderSide: BorderSide(color: Colors.blueAccent, width: 2.0),
                      borderRadius: BorderRadius.all(Radius.circular(32.0)),
                    ),
                  ),
                ),
                new SizedBox(
                  height: 20.0,
                ),
                new Row(children: <Widget>[
                  Container(
                    padding: EdgeInsets.symmetric(horizontal: 20.0),
                    decoration: BoxDecoration(
                      borderRadius: BorderRadius.all(Radius.circular(32.0)),
                      border: Border.all(
                          color: Colors.blueAccent,
                          style: BorderStyle.solid,
                          width: 0.80),
                    ),
                    child: new Expanded(
                        child: new TextFormField(
                      decoration: new InputDecoration(
                        hintText: 'Enter your date of birth',
                        labelText: 'Date of Birth',
                      ),
                      controller: _controller,
                      keyboardType: TextInputType.datetime,
                    )),
                  ),
                  new IconButton(
                    icon: Icon(Icons.keyboard_arrow_down),
                    tooltip: 'Choose date',
                    onPressed: (() {
                      _chooseDate(context, _controller.text);
                    }),
                  )
                ]),
              ]),
            ),
          ),
        );
      }
    }

```

Error Message:

> 
> The following assertion was thrown building Container(padding:
>  EdgeInsets(20.0, 0.0, 20.0, 0.0), bg: BoxDecoration(border:
>  Border.all(BorderSide(MaterialAccentColor(primary value:
>  Color(0xff448aff)), 0.8, BorderStyle.solid)), borderRadius:
>  BorderRadius.circular(32.0))): Incorrect use of ParentDataWidget.
> 
> 
>