private async Task SyncSubject(MyPurdueSubject subject)
{
Console.WriteLine("\tSynchronizing " + subject.SubjectCode + " / " + subject.SubjectName + " ...");
var dbSubjectId = await EnsureSubject(subject.SubjectCode, subject.SubjectName);
// Prepare a cache of all courses
Dictionary <Tuple <string, string>, Course> dbCourseCache;
using (var db = new ApplicationDbContext())
{
dbCourseCache = db.Courses.AsNoTracking().Where(c => c.SubjectId == dbSubjectId)
.ToDictionary(c => new Tuple <string, string>(c.Number, c.Title));
}
Console.WriteLine("\t\tCached " + dbCourseCache.Count + " courses from database.");
// Prepare a cache of all sections
Dictionary <string, Section> dbSectionCache;
using (var db = new ApplicationDbContext())
{
db.Configuration.ProxyCreationEnabled = false;
dbSectionCache = db.Sections.AsNoTracking().Include(s => s.Class).Include(s => s.Meetings.Select(m => m.Room.Building))
.Where(s => s.Class.TermId == TermId && s.Class.Course.SubjectId == dbSubjectId)
.ToDictionary(s => s.CRN);
}
Console.WriteLine("\t\tCached " + dbSectionCache.Count + " sections from database.");
// Fetch sections from MyPurdue
Dictionary <string, MyPurdueSection> sectionsByCrn = null;
sectionsByCrn = await Api.FetchSections(TermCode, subject.SubjectCode);
Console.WriteLine("\t\tFetched " + sectionsByCrn.Count + " sections from MyPurdue.");
// Group sections into classes by matching links
var sectionFlatList = new List <MyPurdueSection>(sectionsByCrn.Values);
var classGroups = GroupSections(sectionFlatList);
// Process and insert each class
foreach (var classGroup in classGroups)
{
// All of the foreign keys we need to find in order to hook sections up
Guid?dbCampusId = null;
Guid?dbCourseId = null;
Guid?dbClassId = null;
// Find the section that'll tell us course number and title (all of them should, but to be safe...)
var sectionWithCourseInfo = classGroup.FirstOrDefault(cg => cg.Number.Length > 0 && cg.Title.Length > 0);
if (sectionWithCourseInfo == null)
{
Console.WriteLine("\t\t** WARNING: No course information (title / number) found for CRNs " + string.Join(", ", classGroup.Select(c => c.Crn)));
continue;
}
Console.WriteLine("\t\t" + subject.SubjectCode + sectionWithCourseInfo.Number + " - " + sectionWithCourseInfo.Title + " ...");
// Do we have any of the sections cached?
var cachedSection = classGroup.Where(s => dbSectionCache.ContainsKey(s.Crn))
.Select(s => dbSectionCache[s.Crn]).FirstOrDefault();
if (cachedSection != null)
{
dbCampusId = cachedSection.Class.CampusId;
dbCourseId = cachedSection.Class.CourseId;
dbClassId = cachedSection.ClassId;
}
// Find or create any elements we don't have ...
if (dbCampusId == null)
{
// Find / create the campus
var sectionWithCampus = classGroup.FirstOrDefault(cg => cg.CampusCode.Length > 0);
if (sectionWithCampus == null)
{
dbCampusId = await EnsureCampus("", ""); // No campus
}
else
{
dbCampusId = await EnsureCampus(sectionWithCampus.CampusCode, sectionWithCampus.CampusName);
}
}
if (dbCourseId == null)
{
// Find / create the course
var courseKey = new Tuple <string, string>(sectionWithCourseInfo.Number, sectionWithCourseInfo.Title);
if (dbCourseCache.ContainsKey(courseKey))
{
dbCourseId = dbCourseCache[courseKey].CourseId;
}
else
{
using (var db = new ApplicationDbContext())
{
var dbCourse = new Course()
{
CourseId = Guid.NewGuid(),
SubjectId = dbSubjectId,
Title = sectionWithCourseInfo.Title,
Number = sectionWithCourseInfo.Number,
Description = sectionWithCourseInfo.Description,
CreditHours = classGroup.OrderByDescending(c => c.CreditHours).FirstOrDefault().CreditHours,
Classes = new List <Class>()
};
db.Courses.Add(dbCourse);
await db.SaveChangesAsync();
dbCourseCache[courseKey] = dbCourse;
dbCourseId = dbCourse.CourseId;
}
}
}
if (dbClassId == null)
{
// Find / create the class
using (var db = new ApplicationDbContext())
{
var dbClass = new Class()
{
ClassId = Guid.NewGuid(),
CampusId = (Guid)dbCampusId,
CourseId = (Guid)dbCourseId,
TermId = TermId,
Sections = new List <Section>()
};
db.Classes.Add(dbClass);
await db.SaveChangesAsync();
dbClassId = dbClass.ClassId;
}
}
// Update / create each section
var updatedSections = new List <Section>();
var newSections = new List <Section>();
var instructorEntities = new Dictionary <Guid, Instructor>();
var newMeetings = new List <Meeting>();
var deleteMeetings = new List <Meeting>();
foreach (var section in classGroup)
{
Section dbSection;
if (dbSectionCache.ContainsKey(section.Crn))
{
dbSection = dbSectionCache[section.Crn];
var sectionChanged = false;
// Check for changes
if (dbSection.ClassId != dbClassId ||
dbSection.Type != section.Type ||
dbSection.Capacity != section.Capacity ||
dbSection.Enrolled != section.Enrolled ||
dbSection.RemainingSpace != section.RemainingSpace ||
dbSection.WaitlistCapacity != section.WaitlistCapacity ||
dbSection.WaitlistCount != section.WaitlistCount ||
dbSection.WaitlistSpace != section.WaitlistSpace)
{
dbSection.ClassId = (Guid)dbClassId;
dbSection.Type = section.Type;
dbSection.Capacity = section.Capacity;
dbSection.Enrolled = section.Enrolled;
dbSection.RemainingSpace = section.RemainingSpace;
dbSection.WaitlistCapacity = section.WaitlistCapacity;
dbSection.WaitlistCount = section.WaitlistCount;
dbSection.WaitlistSpace = section.WaitlistSpace;
sectionChanged = true;
}
// Update meetings
// First, delete any meetings that don't exist in the latest MyPurdue pull
foreach (var meeting in dbSection.Meetings.ToList())
{
// TODO: compare instructors
var matches = section.Meetings.Where(m =>
m.Type == meeting.Type &&
m.StartTime == meeting.StartTime &&
m.EndTime == meeting.StartTime.Add(meeting.Duration) &&
m.DaysOfWeek == meeting.DaysOfWeek &&
m.BuildingCode == meeting.Room.Building.ShortCode &&
m.RoomNumber == meeting.Room.Number
);
if (matches.Count() <= 0)
{
dbSection.Meetings.Remove(meeting);
deleteMeetings.Add(meeting);
sectionChanged = true;
}
}
// Add all of the meetings that don't exist.
var existingMeetings = dbSection.Meetings.ToList(); // copy of list to avoid changes during loop
foreach (var meeting in section.Meetings)
{
var matches = existingMeetings.Where(m =>
m.Type == meeting.Type &&
m.StartTime == meeting.StartTime &&
m.Duration == meeting.EndTime.Subtract(meeting.StartTime) &&
m.DaysOfWeek == meeting.DaysOfWeek &&
m.Room.Building.ShortCode == meeting.BuildingCode &&
m.Room.Number == meeting.RoomNumber
);
if (matches.Count() <= 0)
{
// make sure instructors exist
var instructors = new List <Instructor>();
foreach (var inst in meeting.Instructors)
{
var instructorId = await EnsureInstructor(inst.Item2, inst.Item1);
if (!instructorEntities.ContainsKey(instructorId))
{
instructorEntities[instructorId] = new Instructor()
{
InstructorId = instructorId
};
}
instructors.Add(instructorEntities[instructorId]);
}
// make sure the building exists
var dbBuildingId = await EnsureBuilding((Guid)dbCampusId, meeting.BuildingCode, meeting.BuildingName);
// make sure the room exists
var dbRoomId = await EnsureRoom(dbBuildingId, meeting.RoomNumber);
// Create the actual meeting object
var newMeeting = new Meeting()
{
MeetingId = Guid.NewGuid(),
Type = meeting.Type,
StartTime = meeting.StartTime,
Duration = meeting.EndTime.Subtract(meeting.StartTime),
Instructors = instructors,
RoomId = dbRoomId,
DaysOfWeek = meeting.DaysOfWeek,
SectionId = dbSection.SectionId,
StartDate = meeting.StartDate,
EndDate = meeting.EndDate
};
dbSection.Meetings.Add(newMeeting);
newMeetings.Add(newMeeting);
sectionChanged = true;
}
}
// If we've made any changes, flag this for committing to the DB later
if (sectionChanged)
{
foreach (var m in dbSection.Meetings.ToList())
{
m.Room = null; // Prevent EF from trying to attach the entity
}
dbSection.Class = null; // Prevent EF from trying to find the entity
if (section.Meetings.Count > 0)
{
var startDate = section.Meetings.OrderBy(m => m.StartDate).Select(m => m.StartDate).First();
var endDate = section.Meetings.OrderByDescending(m => m.EndDate).Select(m => m.EndDate).First();
dbSection.StartDate = startDate;
dbSection.EndDate = endDate;
}
updatedSections.Add(dbSection);
}
}
else
{
// Section isn't cached. Create a new one.
dbSection = new Section()
{
SectionId = Guid.NewGuid(),
CRN = section.Crn,
ClassId = (Guid)dbClassId,
Meetings = new List <Meeting>(),
Type = section.Type,
Capacity = section.Capacity,
Enrolled = section.Enrolled,
RemainingSpace = section.RemainingSpace,
WaitlistCapacity = section.WaitlistCapacity,
WaitlistCount = section.WaitlistCount,
WaitlistSpace = section.WaitlistSpace
};
foreach (var meeting in section.Meetings)
{
// make sure instructors exist
var instructors = new List <Instructor>();
foreach (var inst in meeting.Instructors)
{
var instructorId = await EnsureInstructor(inst.Item2, inst.Item1);
if (!instructorEntities.ContainsKey(instructorId))
{
instructorEntities[instructorId] = new Instructor()
{
InstructorId = instructorId
};
}
instructors.Add(instructorEntities[instructorId]);
}
// make sure the building exists
var dbBuildingId = await EnsureBuilding((Guid)dbCampusId, meeting.BuildingCode, meeting.BuildingName);
// make sure the room exists
var dbRoomId = await EnsureRoom(dbBuildingId, meeting.RoomNumber);
var newMeeting = new Meeting()
{
MeetingId = Guid.NewGuid(),
Type = meeting.Type,
StartTime = meeting.StartTime,
Duration = meeting.EndTime.Subtract(meeting.StartTime),
Instructors = instructors,
RoomId = dbRoomId,
DaysOfWeek = meeting.DaysOfWeek,
Section = dbSection,
StartDate = meeting.StartDate,
EndDate = meeting.EndDate
};
dbSection.Meetings.Add(newMeeting);
// We don't need to add to newMeetings here because this is a new section
// and EF will take care of adding new related entities.
}
if (section.Meetings.Count > 0)
{
var startDate = section.Meetings.OrderBy(m => m.StartDate).Select(m => m.StartDate).First();
var endDate = section.Meetings.OrderByDescending(m => m.EndDate).Select(m => m.EndDate).First();
dbSection.StartDate = startDate;
dbSection.EndDate = endDate;
}
newSections.Add(dbSection);
}
}
using (var db = new ApplicationDbContext())
{
db.Configuration.ProxyCreationEnabled = false;
Console.WriteLine("\t\t\t{0} inserted / {1} updated sections", newSections.Count, updatedSections.Count);
// Attach all instructors as unchanged
foreach (var i in instructorEntities.Values)
{
db.Instructors.Attach(i);
db.Entry(i).State = EntityState.Unchanged;
}
foreach (var s in updatedSections)
{
db.Entry(s).State = EntityState.Modified;
}
foreach (var m in deleteMeetings)
{
//db.Meetings.Remove(db.Meetings.Find(m.MeetingId)); // Requires hitting DB twice.
var mid = new Meeting()
{
MeetingId = m.MeetingId
};
db.Meetings.Attach(mid);
db.Meetings.Remove(mid);
}
foreach (var m in newMeetings)
{
db.Meetings.Add(m);
}
foreach (var s in newSections)
{
db.Sections.Add(s);
}
await db.SaveChangesAsync();
}
}
}
