How to: Handle Appointment Conflicts

• Nov 13, 2018
• 5 minutes to read

This example demonstrates how to manually determine whether there are appointment conflicts or not in some particular situations. If you’re not satisfied with the automatic conflicts determination of the XtraScheduler (when appointments are considered to conflict if they have the same resource and their time intervals intersect), you can set the SchedulerOptionsCustomization.AllowAppointmentConflicts property to Custom and handle the SchedulerControl.AllowAppointmentConflicts event to perform your own conflict determination.

In the following example it’s assumed that an appointment is a lecture conducted by a teacher in a classroom, and several groups of students may be present at the same lecture at the same time. Two appointments are consider to be in conflict in the following situations.

• Two different lecturers are scheduled to conduct a lecture at the same time in the same room.
• The same lecturer is scheduled to conduct different lectures at the same time in different rooms.
• The same group is scheduled at the same time in different rooms.

C#

using DevExpress.XtraScheduler;
// ...

// Appointment = Lecture
// Resource = Room
// appointment.CustomFields["Teacher"] = Teacher
// appointment.CustomFields["Group"] = Group of Students

// Start of the AllowAppointmentConflicts event handler.
// ==================================================

private void schedulerControl1_AllowAppointmentConflicts(object sender, 
    AppointmentConflictEventArgs e) {
   Appointment currentLecture = e.Appointment;
   object roomId = currentLecture.ResourceId;
   string teacher = GetTeacher(currentLecture);
   string group = GetGroup(currentLecture);
   DateTime start = currentLecture.Start;
   TimeSpan duration = currentLecture.Duration;

   // e.Conflicts contains all the lectures held at the same time.
   // All of them the SchedulerControl considers to be conflicting.
   AppointmentBaseCollection lecturesInTheSameTime = e.Conflicts;

   AppointmentBaseCollection conflictedLectures = new AppointmentBaseCollection();
   AppointmentBaseCollection lecturesInDifferentRoomWithDifferentTeacher = 
    new AppointmentBaseCollection();
   ArrayList groupsInDifferentRoomWithDifferentTeacher = new ArrayList();
   ArrayList groups = new ArrayList();

   int count = lecturesInTheSameTime.Count;
   for (int i = 0; i < count; i++) {
      Appointment lecture = lecturesInTheSameTime[i];

      // Check if the lecture is in the same room.
      if (Object.Equals(lecture.ResourceId, roomId)) { 
         // Check if the lecture is by the same teacher.
         if (String.Compare(teacher, GetTeacher(lecture), true) == 0) { 
            if (lecture.Start != start || lecture.Duration != duration) {
               // Conflict! Lecture with a bad time frame.
               conflictedLectures.Add(lecture);
            }
            else {
               // No conflict!
               groups.Add(GetGroup(lecture));
            }
         }
         // Lecture by a different teacher.
         else { 
            // Conflict! Lecture by a different teacher in the same room.
            conflictedLectures.Add(lecture);
         }
      }
      // Lecture in a different room.
      else { 
         // Lecture by the same teacher.
         if (String.Compare(teacher, GetTeacher(lecture), true) == 0) { 
            // Conflict! Lecture of the same teacher in the different room.
            conflictedLectures.Add(lecture);
         }
         // Lecture by a different teacher.
         else { 
            // No conflict! Lecture by a different teacher in a different room.
            groupsInDifferentRoomWithDifferentTeacher.Add(GetGroup(lecture));
            lecturesInDifferentRoomWithDifferentTeacher.Add(lecture);
         }
      }
   }

   // Search for the groups which should be in different rooms at the same time.
   count = groups.Count;
   for (int i = 0; i < count; i++) {
      int conflictIndex = groupsInDifferentRoomWithDifferentTeacher.IndexOf(groups[i]);
      if (conflictIndex >= 0)
         conflictedLectures.Add(lecturesInDifferentRoomWithDifferentTeacher[conflictIndex]);
   }

   e.Conflicts.Clear();
   // If the conflictedLectures will contain no lectures after this event has occured, 
   // then e.Conflicts will be empty and this will indicate that there are no conflicts.
   e.Conflicts.AddRange(conflictedLectures);
}

// End of the AllowAppointmentConflicts event handler.
// ==================================================


// Additional functions.
// ====================
// Determines the teacher for the specified lecture.
string GetTeacher(Appointment lecture) {
   object teacher = lecture.CustomFields["Teacher"];
   if (teacher == null)
      return String.Empty;

   return teacher.ToString();
}
// Determines the group for the specified lecture.
string GetGroup(Appointment lecture) {
   object group = lecture.CustomFields["Group"];
   if (group == null)
      return String.Empty;

   return group.ToString();
}

VB.NET

Imports DevExpress.XtraScheduler
' ...

' Appointment = Lecture
' Resource = Room
' appointment.CustomFields["Teacher"] = Teacher
' appointment.CustomFields["Group"] = Group of Students

' Start of the AllowAppointmentConflicts event handler.
' ==================================================

Private Sub OnAllowAppointmentConflicts(sender As Object, e As AppointmentConflictEventArgs) _
Handles SchedulerControl1.AllowAppointmentConflicts

   Dim currentLecture As Appointment = e.Appointment
   Dim roomId As Object = currentLecture.ResourceId
   Dim teacher As String = GetTeacher(currentLecture)
   Dim group As String = GetGroup(currentLecture)
   Dim start As DateTime = currentLecture.Start
   Dim duration As TimeSpan = currentLecture.Duration

   ' e.Conflicts contains all the lectures held at the same time.
   ' All of them the SchedulerControl considers to be conflicting.
   Dim lecturesInTheSameTime As AppointmentBaseCollection = e.Conflicts

   Dim conflictedLectures As New AppointmentBaseCollection()
   Dim lecturesInDifferentRoomWithDifferentTeacher As New AppointmentBaseCollection()
   Dim groupsInDifferentRoomWithDifferentTeacher As New ArrayList()
   Dim groups As New ArrayList()

   Dim count As Integer = lecturesInTheSameTime.Count
   Dim i As Integer
   For i = 0 To count - 1
      Dim lecture As Appointment = lecturesInTheSameTime(i)

      ' Check if the lecture is in the same room.
      If Object.Equals(lecture.ResourceId, roomId) Then
         ' Check if the lecture is by the same teacher.
         If String.Compare(teacher, GetTeacher(lecture), True) = 0 Then
            If (lecture.Start <> start) Or (lecture.End <> start.AddTicks(duration.Ticks)) Then
               ' Conflict! Lecture with a bad time frame.
               conflictedLectures.Add(lecture)
            Else
               ' No conflict!
               groups.Add(GetGroup(lecture))
            End If
         ' Lecture by a different teacher.
         Else
            ' Conflict! Lecture by a different teacher in the same room.
            conflictedLectures.Add(lecture)
         End If
      ' Lecture in a different room.
      Else
         ' Lecture by the same teacher.
         If String.Compare(teacher, GetTeacher(lecture), True) = 0 Then
            ' Conflict! Lecture of the same teacher in the different room.
            conflictedLectures.Add(lecture)
         ' Lecture by a different teacher.
         Else
            ' No conflict! Lecture by different teacher in a different room.
            groupsInDifferentRoomWithDifferentTeacher.Add(GetGroup(lecture))
            lecturesInDifferentRoomWithDifferentTeacher.Add(lecture)
         End If
      End If
   Next i

   ' Search for the groups which should be in different rooms at the same time.
   count = groups.Count
   For i = 0 To count - 1
      Dim conflictIndex As Integer = groupsInDifferentRoomWithDifferentTeacher.IndexOf(groups(i))
      If conflictIndex >= 0 Then
         conflictedLectures.Add(lecturesInDifferentRoomWithDifferentTeacher(conflictIndex))
      End If
   Next i 

   e.Conflicts.Clear()

   ' If the conflictedLectures will contain no lectures after this event occured, then e.Conflicts 
   ' will be empty and this will indicate that there are no conflicts.
   e.Conflicts.AddRange(conflictedLectures)

End Sub

' End of the AllowAppointmentConflicts event handler.
' ==================================================


' Additional functions.
' --------------------

' Determines the teacher for the specified lecture.
Function GetTeacher(lecture As Appointment) As String
   Dim teacher As Object = lecture.CustomFields("Teacher")
   If teacher Is Nothing Then
      Return String.Empty
   End If 

   Return teacher.ToString()
End Function

' Determines the group for the specified lecture.
Function GetGroup(lecture As Appointment) As String
   Dim group As Object = lecture.CustomFields("Group")
   If group Is Nothing Then
      Return String.Empty
   End If

   Return group.ToString()
End Function