sample dropdown in future builder

dropdown.dart

// get log history
            FutureBuilder(
              future: FirebaseFirestore.instance.collection('sick').doc(widget.idcard).collection('logs').get(),
              builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
                if (snapshot.hasError) {
                  return Text('Error: ${snapshot.error}');
                }

                if (!snapshot.hasData) {
                  return Text('Loading...');
                }

                // get data from firebase
                List<DocumentSnapshot> logDocument = snapshot.data!.docs;
                return Center(
                  child: Container(
                    padding: EdgeInsets.symmetric(horizontal: 16),
                    decoration: BoxDecoration(
                      color: Color(0xfff29a94),
                      borderRadius: BorderRadius.circular(32.0),
                    ),
                    child: DropdownButton(
                      hint: Text('ประวัติบันทึกข้อมูล'),
                      items: logDocument.map((doc) {
                        // get datetime format
                        DateTime date = DateTime.fromMillisecondsSinceEpoch(int.parse(doc['timestamp']));
                        final datetimeTitle = DateFormat('dd MMMM yyyy HH:mm').format(date);
                        return DropdownMenuItem(
                          child: Text(datetimeTitle),
                          value: doc['timestamp'],
                        );
                      }).toList(),
                      onChanged: (value) {
                        // find a doocument with docId = value
                        // open new page with data
                        dev.log('goto page with docId = $value');
                      },
                    ),
                  ),
                );
              },
            ),