Unable to cast object of type ‘System.String’ to type ‘System.Boolean .Net Core MVC

I refer this tutorial https://github.com/bhrugen/AppointmentScheduler I did same code but I’m not able to show Get Calendar Data when I running it, It’s shows error – Unable to cast object of type ‘System.String’ to type ‘System.Boolean. My Code is :-

AppointmentApiController.cs :

[HttpGet]
        [Route("GetCalendarData")]
        public IActionResult GetCalendarData(string doctorId)
        {
            CommonResponse<List<AppointmentVM>> commonResponse = new CommonResponse<List<AppointmentVM>>();
            try
            {
                if (role == Helper.Patient)
                {
                    commonResponse.dataenum = _appointmentService.PatientsEventsById(loginUserId);
                    commonResponse.status = Helper.success_code;
                }
                else if (role == Helper.Doctor)
                {
                    commonResponse.dataenum = _appointmentService.DoctorsEventsById(loginUserId);
                    commonResponse.status = Helper.success_code;
                }
                else
                {
                    commonResponse.dataenum = _appointmentService.DoctorsEventsById(doctorId);
                    commonResponse.status = Helper.success_code;
                }
            }
            catch (Exception e)
            {
                commonResponse.message = e.Message;
                commonResponse.status = Helper.failure_code;
            }
            return Ok(commonResponse);
        }

Script.js :

var routeURL = location.protocol + "//" + location.host;
$(document).ready(function () {
    $("#appointmentDate").kendoDateTimePicker({
        value: new Date(),
        dateInput: false
    });

    InitializeCalendar();
});
var calendar;
function InitializeCalendar() {
    try {
        var calendarEl = document.getElementById('calendar');
        if (calendarEl != null) {
            calendar = new FullCalendar.Calendar(calendarEl, {
                initialView: 'dayGridMonth',
                headerToolbar: {
                    left: 'prev,next,today',
                    center: 'title',
                    right: 'dayGridMonth,timeGridWeek,timeGridDay'
                },
                selectable: true,
                editable: false,
                select: function (event) {
                    onShowModal(event, null);
                },
                eventDisplay:'block',
                events: function (frtch, successCallback, failureCallback) {
                    $.ajax({
                        url: routeURL + '/api/Appointment/GetCalendarData?doctorId=' + $("#doctorId").val(),
                        type: 'GET',
                        dataType: 'JSON',
                        success: function (response) {
                            var events = [];
                            if (response.status === 1) {
                                $.each(response.dataenum, function (i, data) {
                                    events.push({
                                        title: data.title,
                                        description: data.description,
                                        start: data.startDate,
                                        end: data.endDate,
                                        backgroundColor: "#162466",
                                        textColor: "white",
                                        id: data.id
                                    });
                                })
                            }
                            successCallback(events);
                        },
                        error: function (xhr) {
                            $.notify("Error", "error");
                        }
                    });
                },
                eventClick: function (info) {
                    getEventDetailsByEventId(info.event);
                }
            });
            calendar.render();
        }
    }
    catch (e) {
        alert(e);
    }
}

AppointmentService.cs :

 public List<AppointmentVM> DoctorsEventsById(string doctorId)
        {
            return _db.Appointments.Where(x => x.DoctorId == doctorId).ToList().Select(c => new AppointmentVM()
            {
                Id = c.Id,
                Description = c.Description,
                StartDate = c.StartDate.ToString("yyyy-MM-dd HH:mm:ss"),
                EndDate = c.EndDate.ToString("yyyy-MM-dd HH:mm:ss"),
                Title = c.Title,
                Duration = c.Duration,
                IsDoctorApproved = c.IsDoctorApproved
            }).ToList();
        }

IAppointmentService.cs :

public List<AppointmentVM> DoctorsEventsById(string doctorId);

Answer

Unable to cast object of type ‘System.String’ to type ‘System.Boolean.

You need to make sure the type of IsDoctorApproved in AppointmentVM is bool:

public class AppointmentVM
{
    public bool IsDoctorApproved {get;set;}
}

Also,you need to make sure the type of IsDoctorApproved in your database is bool.