StreamBuilder<QuerySnapshot>(
        stream: Firestore.instance.collection('route').snapshots(),
        builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
          if (snapshot.hasError) return new Text('Error: ${snapshot.error}');
          switch (snapshot.connectionState) {
            case ConnectionState.waiting:
              return new Text('Loading...');
            default:
              return Container(
                padding: EdgeInsets.symmetric(horizontal: 5.0),
                decoration: BoxDecoration(
                  borderRadius: BorderRadius.circular(15.0),
                  border: Border.all(
                      color: Colors.grey[500],
                      style: BorderStyle.solid,
                      width: 0.80),
                ),
                child: DropdownButtonHideUnderline(
                  child: DropdownButton(
                    isExpanded: false,
                    elevation: 0,
                    hint: Container(
                        child: Row(
                      children: <Widget>[
                        Icon(
                          Icons.swap_vert,
                          color: Colors.grey[500],
                        ),
                        Text('Select a Route'),
                      ],
                    )),
                    value: _selectedRoute,
                    onChanged: (newValue) {
                      setState(() {
                        _selectedRoute = newValue;
                      });
                    },
                    items: snapshot.data.documents
                        .map((DocumentSnapshot document) {
                      return DropdownMenuItem<String>(
                        value: document.data['name'],
                        child: Row(
                          children: <Widget>[
                            new Icon(
                              Icons.swap_vert,
                              size: ScreenUtil.instance.setSp(22.0),
                            ),
                            new Text(' '),
                            new Text(document.data['name']),
                          ],
                        ),
                      );
                    }).toList(),
                  ),
                ),
              );
          }
        })