I have a structure like the following using EF:
An "Event" has many "Guests"
Let's say Event.Guests has 4 Guest elements, with the id's 1,2,3,4
I want to update the Event.Guests to have the guests with id's 3,4,5 (if Guest 5 doesn't exist I want to create it).
What's the most efficient way to remove the existing guests from Event and add the new one?
This is what I'm doing right now:
var newGuests = new List<Guest>();
var existingGuests = #event.Guests.ToList();
// GetNewGuestsIds will return the new guests list (3,4,5)
foreach (var guestId in GetNewGuestsIds())
{
Guest guest = existingGuests.FirstOrDefault(eg => eg.Id == guestId);
if (guest == null)
{
guest = db.Guests.CreateObject();
// fill guest data here
}
newGuests.Add(guest);
}
foreach (var existingGuest in existingGuests)
{
// Remove the existing element from the list to add
var removed = newGuests.RemoveAll(g => g.Id == existingGuest.Id);
if (removed == 0) // The existing host is not on the list to add, delete it
{
#event.EventHosts.Remove(existingGuest);
}
}
foreach (var guest in newGuests)
{
#event.Guests.Add(guest);
}
But I think this might be improved ... I just don't know how.
Thanks!
After some thought I came with this result which seems a lot better:
var existingGuests = #event.Guests.ToList();
// GetNewGuestsIds will return the new guests list (3,4,5)
foreach (var guestId in GetNewGuestsIds())
{
if (existingGuests.RemoveAll(g => g.Id == guestId) == 0)
{
guest = db.Guests.CreateObject();
// fill guest data here
#event.Guests.AddObject(guest);
}
}
existingGuests.ForEach(g => #event.Guests.Remove(g));
I hope this helps someone else.
Related
I have this method that saves an entity with its related items (many-to-many relationship),
private static void Save<T>(TbCommonHistoryLog log, List<T> lstDetails) where T : IHasSerial
{
foreach (var item in lstDetails.OrderBy(x => x.Serial))
{
var ser = SerializeObject(item);
var record = oContext.TbHistoryLog_Lists.FirstOrDefault(x => x.ListObjectJson == ser);
if (record == null) //add new list item
{
TbCommonHistoryLog_Lists listObject = new TbCommonHistoryLog_Lists()
{
ListObjectJson = SerializeObject(item)
};
var details = new TbCommonHistoryLogDetails { TbHistoryLog = log, TbHistoryLog_Lists = listObject };
oContext.TbHistoryLogDetails.Add(details);
}
else //attach an existing list item
{
var o = oContext.TbHistoryLog_Lists.Find(record.Id);
oContext.TbHistoryLog_Lists.Attach(o);
var details = new TbCommonHistoryLogDetails { TbHistoryLog = log, TbHistoryLog_Lists = o };
oContext.TbHistoryLogDetails.Add(details);
}
}
oContext.BulkSaveChanges();
}
I have two tables: TbCommonHistoryLog, TbCommonHistoryLog_Lists, that are in many to many relationship, the joining table is TbCommonHistoryLogDetails,
What I'm doing here is an auditing for master-detail models, all audits are serialized to JSON in DB, I save the head object in the TbCommonHistoryLog table, and every list item in the TbHistoryLog_Lists table, in the mthod above I check if the list item is already exists in the database or not to avoid duplicating.
but this process takes more than 15 seconds which is a very long time, I can't figure out what am I doing wrong here.. please help?
For every single item in collection you're querying database. My suggestion is to save records in var, then ask the variable if the item is in database.
var databaseRecords = oContext.TbHistoryLog_Lists.ToList();
Then in the loop:
var record = databaseRecords.FirstOrDefault(x => x.ListObjectJson == ser);
This seems like it should be easy. Maybe it is and I'm just overthinking it. I have a bunch of items that have a category field set via a DropLink. I want to grab all of the items that match one of those options. E.g., Grab a list of all items where Category=Brochure. I can't seem to get the ID of the Droplink option to match against the Category option on the Item itself.
EDIT: Included current code by request.
public List<PoolDownload> Manuals
{
get
{
LookupField cat = (LookupField)this.Item.Fields["Category"];
return this.Downloads.Where(i => (i.Item.TemplateID == PoolDownload.TemplateId) &&
(i.Item.GlassCast<Pdp.Pool.Website.Business.Entities.PoolDownload>().Category.ToString() == cat.TargetID.ToString()))
.ToList();
}
}
I believe the problem is you're comparing a Guid.ToString() to a Sitecore.Data.ID.ToString(). These two statements return different values:
var guidToString = Sitecore.Context.Item.ID.Guid.ToString();
// "2a6a1d9a-be1d-411b-821a-7e63775280b3"
var idToString = Sitecore.Context.Item.ID.ToString();
// "{2A6A1D9A-BE1D-411B-821A-7E63775280B3}"
Cast the TargetID to a Guid as well and you should be good.
And to answer your question in your comment below about displaying the "Download Items" grouped by Category, you could use the GroupBy method, https://msdn.microsoft.com/en-us/library/bb534304(v=vs.110).aspx like this:
public IEnumerable<IGrouping<Guid, PoolDownload>> Manuals
{
get
{
LookupField cat = (LookupField)this.Item.Fields["Category"];
return this.Downloads.Where(i =>
i.Item.TemplateID == PoolDownload.TemplateId
&& i.Item.GlassCast<Pdp.Pool.Website.Business.Entities.PoolDownload>().Category.ToString() == cat.TargetID.Guid.ToString())
.GroupBy(i => i.Category);
}
}
And then, to loop over the results in the new Manuals property, you could do something like this:
foreach(var categoryGroup in Manuals)
{
var categoryGuid = categoryGroup.Key;
foreach(var download in categoryGroup)
{
var downloadInCurrentGroup = download.Item;
}
}
I have this list of 2000+ categories that need to be organized in a tree before being sent to the controller and the View so the javascript plugin can render them correctly.
I am already doing this but the performance is terrible. It is taking like 30 seconds to assemble the tree.
I can't see what is dropping performance here. Can you guys help me to improve this code?
var allCategories = dal.Listar();
List<Model.Entity.CategoriaCursoEADVO> nestedCategories = new List<Model.Entity.CategoriaCursoEADVO>();
foreach (Model.Entity.CategoriaCursoEAD item in allCategories)
{
if (item.IdCategoriaPai == null)
{
CategoriaCursoEADVO child = new CategoriaCursoEADVO();
child.id = item.Id;
child.text = item.Descricao;
nestedCategories.Add(child);
FillChild(allCategories, child, item.Id);
}
}
And here is the FillChild method:
public int FillChild(IEnumerable<CategoriaCursoEAD> categorias, CategoriaCursoEADVO parent, int IID)
{
var childCategories = categorias.Where(w => w.IdCategoriaPai.Equals(IID));
parent.children = new List<CategoriaCursoEADVO>();
if (childCategories.Count() > 0)
{
foreach (CategoriaCursoEAD cat in childCategories)
{
CategoriaCursoEADVO child = new CategoriaCursoEADVO();
child.id = cat.Id;
child.text = cat.Descricao;
parent.children.Add(child);
FillChild(categorias, child, cat.Id);
}
return 0;
}
else
{
return 0;
}
}
I think the problem is with the new instances and tried using Parallel loops with no satisfatory level of improvement.
This is a pretty good time to use a HashTable (Dictionary). Something like the below code should help.
// Convert the flat list into a hash table with the ID
// of the element as the key
var dict = allCategories.ToDictionary (i => i.Id);
// Group categories by the parent id
var parentGrouping = allCategories.Where(c => c.IdCategoriaPai != null).GroupBy(c => c.ParentId);
// Since we group the items by parent id, we can find
// the parent by id in the dictionary and add the children
// that have that particular id.
foreach(var groupItem in parentGrouping)
if(groupItem.Key != null)
dict[(int)groupItem.Key].children.AddRange(groupItem);
// Get the root elements.
var hierarchicalCategories = allCategories.Where(item => item.IdCategoriaPai == null);
// Do what you need to do here.
This code will create a tree of categories. hierarchicalCategories will contain direct references to the root elements (categories that do not have a parent), assuming that your data is structured that way.
So i have a function that gets a list of students from a web service and also query the localdb for all the students in there. the data is placed in two different list. So i want to check to see if a new student already exists in the localdb List. if it does, update it and it if doesn't then add it. i unable to get it working . I am trying to perform this using LINQ, but i can't seem to get it working right. My LINQ skills are amateurish at best.
public async Task GetStudents()
{
String controllerName = "Students";
List<Students> newStudentData = await RunGetAsync<Students>(controllerName);
// get all the service types that already exists in the localStudent Db
List<Students> currentStudentData = db.Studentss.ToList();
foreach (Students existingStudents in currentStudentData)
{
foreach (Students newStudents in newStudentData)
{
IEnumerable<Students> selectStudents = from student in newStudentData // check if Students exist in the database
where student.Id == existingStudents.Id
select student;
if (selectStudents == null) // didn't find it, then add it
{
db.Students.Add(newStudents);
}
if (selectStudents != null) // found it , then update the informations
{
Students updatedStudents = new Students();
foreach (var field in selectStudents)
{
updatedStudents.FName = field.FName;
updatedStudents.LName = field.LName;
updatedStudents.ZipCode = field.ZipCode;
updatedStudents.AccessCode = field.AccessCode;
}
db.Entry(updatedStudents).State = System.Data.Entity.EntityState.Modified;
}
}
}
db.SaveChanges();
}
Thank you very much for your help.
you're looping more than you need :
foreach (Students newStudents in newStudentData)
{
var student = currentStudentData.FirstOrDefault(s => s.Id == newStudents.Id);
if(student == null)
{
//add
}
else
{
//update
}
}
with FirstOrDefault you can find out if it exists and get a reference to it at the same time, if it does.
You could use Intersect and Except like below:
//Find students that already exist to update
var updateStudents = currentStudentData.Intersect(newStudentData);
//Find new students to add
var addStudents = newStudentData.Except(currentStudentData);
I have the following....
var jobsApplications = ( from applications in db.applications
where applications.employeeId == LogedUser.Id
select new { applications.id, applications.jobId, applications.confirmationDate });
Now I want to navigate this result like
foreach "something" in jobsApplications
But I don't now what to put in something since the select new create a new class.
Any suggestions
I guess you can let the compiler do the work for you:
foreach (var application in jobApplications)
{
// use the application wisely
}
Consider using Array.ForEach() to iterate through your IEnumerable or List. This is a bit more heavyweight.
Array.ForEach(jobsApplication, jobApp => {
if (jobApp.City == "Chicago")
{
jobApp.Approved = true;
}
});
If you want a simple foreach, then you can type the anonymous class as var
foreach (var jobApp in jobApplications)
{
if (jobApp.City == "Chicago")
{
jobApp.Approved = true;
}
}