I have help this LINQ request :
My c#:
var stats = UoW.Repository
.Get(echangeFilter)
.GroupBy(a => new
{
Id = MyBLL.IsInComing(a.idSens) ? MyBLL.FindByNoContactModel(a.change.idTo.GetValueOrDefault()).id : MyBLL.FindByNoContactModel(a.change.idFrom.GetValueOrDefault()).id,
Tri = MyBLL.IsInComing(a.idSens) ? MyBLL.FindByNoContactModel(a.change.idTo.GetValueOrDefault()).Tri: MyBLL.FindByNoContactModel(a.change.idFrom.GetValueOrDefault()).Tri,
SensAppel = a.echange_sens.nom
})
.Select(group => new
{
group.Key.Id,
group.Key.Tri,
group.Key.SensAppel,
Count = group.Count(),
})
.OrderBy(g => g.Tri)
.ToList();
It works but I want to remove this horrible duplication (Id and Tri) in this groupBy, how can I deal with that ? In the concept, I want to use a variable to call this ternary once
If you use the query syntax, you can declare variables.
This is how your query would look like in query syntax (please name your variables properly. I don't know what you are actually doing so I can't name them...):
var query = from a in UoW.Repository
.Get(echangeFilter)
group a by new
{
Id = MyBLL.IsInComing(a.idSens) ? MyBLL.FindByNoContactModel(a.change.idTo.GetValueOrDefault()).id : MyBLL.FindByNoContactModel(a.change.idFrom.GetValueOrDefault()).id,
Tri = MyBLL.IsInComing(a.idSens) ? MyBLL.FindByNoContactModel(a.change.idTo.GetValueOrDefault()).Tri: MyBLL.FindByNoContactModel(a.change.idFrom.GetValueOrDefault()).Tri,
SensAppel = a.echange_sens.nom
} into g
let b = new
{
group.Key.Id,
group.Key.Tri,
Count = group.Count(),
}
orderby g.Tri
select g;
var stats = query.ToList();
Now we can introduce a let:
var query = from a in UoW.Repository
.Get(echangeFilter)
let x = MyBLL.IsInComing(a.idSens) ? MyBLL.FindByNoContactModel(a.change.idTo.GetValueOrDefault()) : MyBLL.FindByNoContactModel(a.change.idFrom.GetValueOrDefault())
group a by new
{
Id = x.id,
Tri = x.Tri,
SensAppel = a.echange_sens.nom
} into g
let b = new
{
g.Key.Id,
g.Key.Tri,
Count = g.Count(),
}
orderby g.Tri
select g;
var stats = query.ToList();
Is this what you're looking for?
var stats = UoW.Repository
.GroupBy(a => {
var repo = MyBLL.IsInComing(a.idSens) ? MyBLL.FindByNoContactModel(a.change.idTo.GetValueOrDefault()) : MyBLL.FindByNoContactModel(a.change.idFrom.GetValueOrDefault())
return new
{
Id = repo.id,
Tri = repo.Tri,
SensAppel = a.echange_sens.nom
}
})
.Select(group => new
{
group.Key.Id,
group.Key.Tri,
Count = group.Count(),
})
.OrderBy(g => g.Tri)
.ToList();
This works by first returning whatever model FindByNoContactModel returns per record and SensAppel, so you only have to call the IsIncoming and FindByNoContactModel once per row. Depending on how many rows you expect to be returned, you may find very quickly that you are better off pushing these lookups elsewhere, or letting the database do it.
var stats = UoW.Repository
.Get(echangeFilter)
.Select(a=> new {
Model = MyBLL.IsIncoming(a.idSens)
? MyBLL.FindByNoContactModel(a.change.idTo.GetValueOrDefault())
: MyBLL.FindByNoContactModel(a.change.idFrom.GetValueOrDefault()),
SensAppel = a.echange_sens.nom
})
.GroupBy(a => new
{
Id = a.Model.id,
Tri = a.Model.Tri,
SensAppel = a.SensAppel
})
.Select(group => new
{
group.Key.Id,
group.Key.Tri,
group.Key.SensAppel,
Count = group.Count(),
})
.OrderBy(g => g.Tri)
.ToList();
You can combine the sub-expressions by pulling out the common elements and then using an intermediate anonymous class to hold them (I am not sure how EF 6 will handle this (what does Get return?) as I don't know what MyBLL is):
var stats = UoW.Repository
.Get(echangeFilter)
.Select(a => new {
a.echange_sens.nom,
fncm = MyBLL.FindByNoContactModel(
(MyBLL.IsInComing(a.idSens)
? a.change.idTo
: a.change.idFrom)
.GetValueOrDefault())
})
.GroupBy(nf => new {
Id = nf.fncm.id,
Tri = nf.fncm.Tri,
SensAppel = nf.nom
})
.Select(group => new {
group.Key.Id,
group.Key.Tri,
Count = group.Count(),
})
.OrderBy(g => g.Tri)
.ToList();
Related
I have a complex LINQ Query to extract Top students in my university. Here is the query :
var query = Db.Students.AsNoTracking().Where(...).AsQueryable();
var resultgroup = query.GroupBy(st => new
{
st.Student.CourseStudyId,
st.Student.EntranceTermId,
st.Student.StudyingModeId,
st.Student.StudyLevelId
}, (key, g) => new
{
CourseStudyId = key.CourseStudyId,
EntranceTermId = key.EntranceTermId,
StudyingModeId = key.StudyingModeId,
StudyLevelId = key.StudyLevelId,
list = g.OrderByDescending(x =>
x.StudentTermSummary.TotalAverageTillTerm).Take(topStudentNumber)
}).SelectMany(q => q.list).AsQueryable();
This Query give me top n students based on 4 parameters and on their TotalAverageTillTerm.
Now I want to add rownum for each group to simulate Total rank, for example Output is :
Now I want to Add TotalRank as rownumber like Sql. In the picture X1=1,X2=2,X3=3 and Y1=1,Y2=2,Y3=3
If I want to reduce problem. I only work on one group. Code Like this :
resultgroup = query.GroupBy(st => new
{
st.Student.StudyLevelId
}, st => st, (key, g) => new
{
StudyLevelId = key.StudyLevelId,
list = g.OrderByDescending(x =>
x.StudentTermSummary.TotalAverageTillTerm)
.Take(topStudentNumber)
}).SelectMany(q => q.list).AsQueryable();
list was a List of student but I see no sign of student having a rank property so I wrapped it into a annonimous type with rank.
var query = Db.Students.AsNoTracking().Where(...).AsEnumerable();
var resultgroup = query.GroupBy(st => new {
st.Student.CourseStudyId,
st.Student.EntranceTermId,
st.Student.StudyingModeId,
st.Student.StudyLevelId
})
.SelectMany( g =>
g.OrderByDescending(x =>x.StudentTermSummary.TotalAverageTillTerm)
.Take(topStudentNumber)
.Select((x,i) => new {
CourseStudyId = g.Key.CourseStudyId,
EntranceTermId = g.Key.EntranceTermId,
StudyingModeId = g.Key.StudyingModeId,
StudyLevelId = g.Key.StudyLevelId,
Rank = i+1
//studentPorperty = x.Prop1,
})
)
.AsQueryable();
Do you mean :
var query = Db.Students.AsNoTracking().Where(...).AsQueryable();
var resultgroup = query.GroupBy(st => new
{
st.Student.CourseStudyId,
st.Student.EntranceTermId,
st.Student.StudyingModeId,
st.Student.StudyLevelId
}, (key, g) => new
{
CourseStudyId = key.CourseStudyId,
EntranceTermId = key.EntranceTermId,
StudyingModeId = key.StudyingModeId,
StudyLevelId = key.StudyLevelId,
list = g.OrderByDescending(x =>
x.StudentTermSummary.TotalAverageTillTerm)
.Take(topStudentNumber)
.Select((x, i) => new { Item = x, TotalRank = i /* item number inside group */}),
StudentsInGroupCount = g.Count() // count group this items
}).SelectMany(q => q).AsQueryable();
To see the results :
foreach (var item in resultgroup.ToList())
{
item.list.ForEach(s => Console.WriteLine(s.TotalRank));
}
How do I create groups and subgroup1 and subgroup2 Use linq.
Example of this picture
I want to create json.
Example of this picture.
I tried to do this but there was a problem.
The items are repeated within one subgroup2.
var list = result
.GroupBy(x => new { x.GroupId, x.GroupName })
.Select(g => new
{
ID = g.Key.GroupId,
Name = g.Key.GroupName,
SubGroup1 = g.GroupBy(x => new { x.SubGroupID1, x.SubGroupName1 })
.Select(cg => new
{
ID = cg.Key.SubGroupID1,
Name = cg.Key.SubGroupName1,
SubGroup2 = g.GroupBy(x => new { x.SubGroupID2, x.SubGroupName2 })
.Select(ii => new
{
ID = ii.Key.SubGroupID2,
Name = ii.Key.SubGroupName2,
item = ii.GroupBy(x => new { x.Stock_Id, x.Stock_Name, x.Prices, x.ScreenNumber })
.Select(oo => new
{
Stock_Id = oo.Key.Stock_Id,
Stock_Name = oo.Key.Stock_Name,
Prices = oo.Key.Prices,
ScreenNumber = oo.Key.ScreenNumber
}).OrderBy(Or => Or.Stock_Id)
.ToList()
}).OrderBy(Or => Or.ID)
.ToList()
}).OrderBy(Or => Or.ID)
.ToList()
}).OrderBy(Or => Or.ID)
.ToList();
Your query could be a lot cleaner if you grouped the groups up front, then project out to your desired results.
var query =
from x in data
group new { x.StockId, x.StockName, x.Prices, x.ScreenNumber }
by new { x.GroupId, x.GroupName, x.SubGroupId1, x.SubGroupName1, x.SubGroupId2, x.SubGroupName2 }
into g
group g
by new { g.Key.GroupId, g.Key.GroupName, g.Key.SubGroupId1, g.Key.SubGroupName1 }
into g2
group g2
by new { g2.Key.GroupId, g2.Key.GroupName }
into g1
select new
{
Id = g1.Key.GroupId,
Name = g1.Key.GroupName,
SubGroup1 = g1.Select(g2 => new
{
Id = g2.Key.SubGroupId1,
Name = g2.Key.SubGroupName1,
SubGroup2 = g2.Select(g => new
{
Id = g.Key.SubGroupId2,
Name = g.Key.SubGroupName2,
Items = g.Select(x => new
{
x.StockId,
x.StockName,
x.Prices,
x.ScreenNumber,
}),
}),
}),
};
The idea is to start off with the most specific grouping first, then one-by-one group the groups by the next layer, and so on.
SubGroup2 = g.GroupBy(x => new { x.SubGroupID2, x.SubGroupName2 })
You are grouping g instead of cg.
I suggest structuring your code a bit, which would help avoiding this kind of mistake.
I have problem with linq query. In Select I am getting the same item twice which makes code execution much longer than I can afford. Is there any way to store x.OrderByDescending(z => z.Date).FirstOrDefault() item inside Select query?
Execution time: 180 ms
var groups = dataContext.History
.GroupBy(a => new { a.BankName, a.AccountNo })
.Select(x => new HistoryReportItem
{
AccountNo = x.FirstOrDefault().AccountNo,
BankName = x.FirstOrDefault().BankName,
IsActive = x.FirstOrDefault().IncludeInCheck,
})
.ToList();
Execution time: 1200 ms
var groups = dataContext.History
.GroupBy(a => new { a.BankName, a.AccountNo })
.Select(x => new HistoryReportItem
{
AccountNo = x.FirstOrDefault().AccountNo,
BankName = x.FirstOrDefault().BankName,
IsActive = x.FirstOrDefault().IncludeInCheck,
LastDate = x.OrderByDescending(z => z.Date).FirstOrDefault().Date,
})
.ToList();
Execution time: 2400 ms
var groups = dataContext.History
.GroupBy(a => new { a.BankName, a.AccountNo })
.Select(x => new HistoryReportItem
{
AccountNo = x.FirstOrDefault().AccountNo,
BankName = x.FirstOrDefault().BankName,
IsActive = x.FirstOrDefault().IncludeInCheck,
LastDate = x.OrderByDescending(z => z.Date).FirstOrDefault().Date,
DataItemsCount = x.OrderByDescending(z => z.Date).FirstOrDefault().CountItemsSend
})
.ToList();
You can try doing the select in two steps:
var groups = dataContext.History
.GroupBy(a => new { a.BankName, a.AccountNo })
.Select(x => new
{
first = x.FirstOrDefault();
lastDate = x.OrderByDescending(z => z.Date).FirstOrDefault();
}
.Select(x => new HistoryReportItem
{
AccountNo = x.first.AccountNo,
BankName = x.first.BankName,
IsActive = x.first.IncludeInCheck,
LastDate = x.lastDate.Date,
DataItemsCount = x.lastDate.CountItemsSend
})
.ToList();
If this fails, it might be because the engine can't convert it completely to SQL, and you can try adding an AsEnumerable() between the two Selects.
I fear that I'm doing n+1 query here, how can I improve this?
var inventories = AppContext.Inventories
.GroupBy(i => new { i.LocationId, i.ProductId })
.Select(g => new InventoryAvailableQuantity
{
ProductId = g.Key.ProductId,
LocationId = g.Key.LocationId,
Product = g.FirstOrDefault().Product.Name,
Location = g.FirstOrDefault().Location.Name,
PurchasePrice = AppContext.Inventories.Where(i => i.ProductId == g.Key.ProductId).OrderByDescending(i => i.DateAdded).FirstOrDefault().PurchasePrice,
ResellerPrice = AppContext.Inventories.Where(i => i.ProductId == g.Key.ProductId).OrderByDescending(i => i.DateAdded).FirstOrDefault().ResellerPrice,
RetailPrice = AppContext.Inventories.Where(i => i.ProductId == g.Key.ProductId).OrderByDescending(i => i.DateAdded).FirstOrDefault().RetailPrice
}).ToList();
You can use comprehension instead of method and gain the ability to use "let":
var inventories = from inv in AppContext.Inventories
group inv by new { i.LocationId, i.ProductId } into g
let firstInv = g.FirstOrDefault()
let firstPur = AppContext.Inventories
.Where(i => i.ProductId == g.Key.ProductId)
.OrderByDescending(i => i.DateAdded)
.FirstOrDefault()
select new InventoryAvailableQuantity
{
ProductId = g.Key.ProductId,
LocationId = g.Key.LocationId,
Product = firstInv.Product.Name,
Location = firstInv.Location.Name,
PurchasePrice = firstPur.PurchasePrice,
ResellerPrice = firstPur.ResellerPrice,
RetailPrice = firstPur.RetailPrice
}; // ( select ... { ... }).ToList(); if you will
Fast answer
var inventories = Inventories
.GroupBy(i => new {i.LocationId, i.ProductId})
.Select(g => new
{
g.Key.ProductId,
g.Key.LocationId,
CurrentInventories = g.FirstOrDefault(),
LastInventories = Inventories.Where(i => i.ProductId == g.Key.ProductId).OrderByDescending(i => i.DateAdded).FirstOrDefault()
})
.Select(g => new InventoryAvailableQuantity
{
ProductId = g.ProductId,
LocationId = g.LocationId,
Product = g.CurrentInventories.Product.Name,
Location = g.CurrentInventories.Location.Name,
PurchasePrice = g.LastInventories.PurchasePrice,
ResellerPrice = g.LastInventories.ResellerPrice,
RetailPrice = g.LastInventories.RetailPrice
})
.ToList();
You can take last item after grouping and take what you want.
var residenceRep =
ctx.ShiftEmployees
.Include(s => s.UserData.NAME)
.Include(s => s.ResidenceShift.shiftName)
.Join(ctx.calc,
sh => new { sh.empNum, sh.dayDate },
o => new { empNum = o.emp_num, dayDate = o.trans_date },
(sh, o) => new { sh, o })
.Where(s => s.sh.recordId == recordId && s.o.day_flag.Contains("R1"))
.OrderBy(r => r.sh.dayDate)
.Select(r => new
{
dayDate = r.sh.dayDate,
empNum = r.sh.empNum,
empName = r.sh.UserData.NAME,
shiftId = r.sh.shiftId,
shiftName = r.sh.ResidenceShift.shiftName,
recordId,
dayState = r.o.day_desc.Split('[', ']')[1]
}).ToList();
I get an exception :
The LINQ expression node type 'ArrayIndex' is not supported in LINQ to
Entities
How i could find an alternative to Split('[', ']')[1] in this query
You must commit the query and do the split after loading the data:
var residenceRep =
ctx.ShiftEmployees
.Include(s => s.UserData.NAME)
.Include(s => s.ResidenceShift.shiftName)
.Join(ctx.calc,
sh => new { sh.empNum, sh.dayDate },
o => new { empNum = o.emp_num, dayDate = o.trans_date },
(sh, o) => new { sh, o })
.Where(s => s.sh.recordId == recordId && s.o.day_flag.Contains("R1"))
.OrderBy(r => r.sh.dayDate)
.Select(r => new
{
dayDate = r.sh.dayDate,
empNum = r.sh.empNum,
empName = r.sh.UserData.NAME,
shiftId = r.sh.shiftId,
shiftName = r.sh.ResidenceShift.shiftName,
recordId = r.sh.recordId,
dayState = r.o.day_desc,
})
.ToList()//Here we commit the query and load data
.Select(x=> {
var parts = x.dayState.Split('[', ']');
return new {
x.dayDate,
x.empNum,
x.empName,
x.shiftId,
x.shiftName,
x.recordId,
dayState = parts.Length > 1 ?parts[1]:"",
};
})
.ToList();
I had this Issue and the approach that I've chose was that get all element I wanted and save them into a List and then filter the actual data on that list.
I know this is not the best answer but it worked for me.