I've been trying to get an IQueryable with distinct and ordered values, but I've found that I can't apply a distinct after orderby or I'll lose the order.
The last query I tried was the following:
IQueryable<gbd_Pages> Listpagespages =
(from c in _db.gbd_Content
where c.IsActive == true && c.IsDeleted == false &&
c.gbd_Template_Fields.SortOrder == sortOrder
orderby c.Content ascending
select c.gbd_Pages);
With this I get repeated results.
The table I want returned is gbd_Pages which has a relation of 1 to many with gbd_Content.
With this i mean that gbd_Content will have a foreign key that will have the primary key of gbd_Pages.
I need to do a sortOrder by the table gbd_Template_Fields wich has a relation 1 to 1 with gbd_Content.
Is there a way for me to do this? I need it to be an IQueryable without converting to IEnumerable or list.
I believe what you need is something like this:
var query =
from p in _db.gbd_Pages
from pc in (from c in p.gbd_Content
where c.IsActive == true && c.IsDeleted == false &&
c.gbd_Template_Fields.SortOrder == sortOrder
orderby c.Content ascending
select c).Take(1)
orderby pc.Content ascending
select p;
So you start from one side of the relationship (to avoid the need of Distinct), then you select a single record from the many side matching the criteria and having the smaller value of the sorting field (using ordered subquery + Take(1)), and finally sort the result using the sort field value from that single child record.
I'm assuming you have inverse collection navigation property from gbd_Pages to gbd_Content. If you don't, replace the p.gbd_Content with _db.gbd_Content where c.[gbd_Content_FK] == p.[PK].
Your primary from needs to be the gbd_Pages table, rather than gbp_Content if those are the results that you want to return. I'll have to assume a foreign key here but you'd want to change to something like;
IQueryable<gbd_Pages> Listpagespages = _db.gbp_Pages
.Where(p => (from c in _db.gbd_Content
where c.IsActive == true
&& c.IsDeleted == false
select c.gbd_Pages.PrimaryKeyID)
.Any())
.Select(p => new
{
// select specific fields here...
p,
SortCol = _db.gbp_Content
.FirstOrDefault(c => c.PrimaryKeyID)
.Where(c => c.IsActive == true && c.IsDeleted == false &&
c.gbd_Template_Fields.SortOrder == sortOrder)
.Select(c => c.Content)
})
.OrderBy(v => c.SortCol);
Try this:
IQueryable<gbd_Pages> Listpagespages = _db.gbd_Content
.Select (c=>new { c.gbd_Pages })
.Where(c=>c.IsActive == true && c.IsDeleted == false &&c.gbd_Template_Fields.SortOrder == sortOrder)
.Distinct()
.OrderBy(c => c.Content)
.Select(c => c.gbd_Pages)
Related
Using SQL Server and C#:
I have 3 tables: Employee (EmployeeId, JobDescription), CashAllowance (CashAllowanceId) and EmployeeCashAllowance (EmployeeId, CashAllowanceId, ValueTaken, DateAdded).
Employee has (EmployeeeId) as primary key, CashAllowance has (CashAllowanceId) as primary key, EmployeeCashAllowance has 2 foreign keys (EmployeeId and CashAllowanceId) related to the first 2 tables.
I need to get the list of (EmployeeCashAllowance) in a specific date + for specific CashAllowanceId + for employees having JobDescription = "Dev"
I need to achieve this in a LINQ query on lists filled from DB where list of all EmployeeCashAllowance is a property of the Employee object (each Employee object has List ListEmployeeCashAllowances as a property). What I wrote was this:
var sumValues = (from e in Employees
where (e.JobDescription == "Dev")
from c in e.ListEmployeeCashAllowances
where (c.EmployeeId == e.EmployeeId && c.CashAllowanceId == selectedCashAllowanceId && c.DateAdded == selectedDate)
select c).ToList();
But this is not working as I expected, it's returning all rows in Employee and EmployeeCashAllowance whatever the selected criteria is (even is JobDescription is not Dev and CashAllowanceId is not the selectedCashAllowanceId).
Where did I go wrong with this?
You better use join I suppose try something like this , I haven't tested so it must look like this
var sumValues = (from e in Employees
join c in EmployeeCashAllowances on e.EmployeeId equals c.EmployeeId
where ( c.CashAllowanceId == selectedCashAllowanceId && c.DateAdded == selectedDate && e.JobDescription == "Dev")
select c).ToList();
Not Tested, Just gave a try
var results = from e in Employees
from ec in e.EmployeeCashAllowances
where (e.EmployeeId == ec.EmployeeId && ec.CashAllowanceId == selectedCashAllowanceId && ec.DateAdded == selectedDate && e.JobDescription == "Dev")
select ec;
Well, I didn't expect this, but I had to change from the query to get what I want, with the restriction that I had use "Sum" and get sum of values in the list of EmployeeCashAllowance resulted:
Employees.SelectMany(e => e.ListEmployeeCashAllowances).Where(lc => lc.CashAllowanceId == selectedCashAllowanceId).Select(c => c.ValueTaken).Sum();
Note that if I don't use Sum the list returned will contain all items in all the ListEmployeeCashAllowances.
It becomes clear when you clean the formatting:
var sumValues =
from e in Employees
where
e.JobDescription == "Dev"
from c in e.ListEmployeeCashAllowances // Gotcha!!!
where
c.EmployeeId == e.EmployeeId && // Is that really necessary?
c.CashAllowanceId == selectedCashAllowanceId &&
c.DateAdded == selectedDate
select c;
Normally I use LINQ methods like:
var query = Employees
.Where(e => e.JobDescription == "Dev")
.SelectMany(e => e.ListEmployeeCashAllowances)
.Where(c =>
c.CashAllowanceId == selectedCashAllowanceId &&
c.DateAdded == selectedDate);
But 'e.ListEmployeeCashAllowances' still can be selecting all users...
A long shot, without knowing your environment, could be:
var query = Employees
.SelectMany(e => e.ListEmployeeCashAllowances)
.Where(c =>
c.JobDescription == "Dev" &&
c.CashAllowanceId == selectedCashAllowanceId &&
c.DateAdded == selectedDate);
Resolving what to do with 'query', you can simply do:
var sumValues = query.Sum(c => c.ValueTaken);
I have the following setup:
Table ShoeAreas that has columns ShoeId and MaterialId.
Table Shoes that has columns ID and Status.
I have a method that takes one argument - materialId and the goal is to determine if there is a record in ShoeAreas with a MaterialId equal to the one passed like an argument. And if such a record (or records most probably) exist if they are relateed to shoe from Shoes withStatus` = Production.
I tried this :
return shoeService.All().
Join(shoeAreaService.All(),
s => s.ID,
sa => sa.ShoeId,
(s, sa) => (sa.MaterialId == matId)).
Any(s => (s.Status == (byte)EntityStatusProd.Production)));
But I get error on the Any.. line saying } expected and also this is my second Linq to Entity query that I write so I have doubts if it's syntax problem or the query is wrong itself.
You are returning IEnumerable<bool> from Join method (values of condition sa.MaterialId == matId). Create anonymous type which will hold both joined entities instead:
return shoeService.All()
.Join(shoeAreaService.All(),
s => s.ID,
sa => sa.ShoeId,
(s, sa) => new { s, sa }) // here
.Any(x => (x.sa.MaterialId == matId) &&
(x.s.Status == (byte)EntityStatusProd.Production)));
you can try this: (linq )
from shoe in Shoes
join shoeArea in ShoesArea on shoe.ID equals shoeArea.ShoeID
where shoeArea.MeterialID == matID && shoe.Status == (byte)EntityStatusProd.Production
select new {shoe.ID,shoe.Status};
return shoeService.All().Any(s => shoeAreaService.All()
.Any(sa => sa.MaterialId == matId
&& s.Id == sa.ShoeId)
&& s.Status == (byte)EntityStatusProd.Production);
I have a List that contains Supplier data and I would like to search it by using SupplierID, non-active supplier and only 1 latest result.
So I've got:
List<Supplier> filteredList = this.toList();
filteredList.OrderByDescending(m => m.ModifiedDatetime).FirstOrDefault();
filteredList.Where(f => (f.Active == false && f.FieldId == SupplierFieldID))
.ToList<Supplier>();
But I can't make this work; please help.
You need to chain your LINQ expressions, like this:
var filteredList = unfilteredData
.Where(f => f.Active == false && f.FieldId == SupplierFieldID)
.OrderByDescending(m => m.ModifiedDatetime)
.FirstOrDefault();
You do not need a ToList(), because you need a single item, not a list; this is what FirstOrDefault() does. If you need the last item, you need to order by the reverse of your original ordering condition. For example, if you would like the entry with the latest modified date, you need to order by descending (as you did).
You can do this in one statement, chaining together the LINQ operators:
var filteredList = myList.Where(f => f.Active == false && f.FieldId == SupplierFieldID)
.OrderByDescending(m => m.ModifiedDatetime)
.Take(1);
or as #Preston Guillot suggested, the even shorter form:
var filteredList = unfilteredData
.OrderByDescending(m => m.ModifiedDatetime)
.FirstOrDefault(f => f.Active == false && f.FieldId == SupplierFieldID);
I want to return a list of a certain entity grouped by a certain property, ordered descending by timestamp and paginated (using Skip and Take). What I got is this:
container.CoinMessageSet.Where(
c => c.MessageState != MessageStateType.Closed &&
(c.DonorOperator.OperatorCode.Equals("opcode") ||
c.RecipientOperator.OperatorCode.Equals("opcode"))
).OrderByDescending(c => c.TimeStamp)
.GroupBy(c => c.Reference).Skip(x).Take(100);
Upon execution I got the Exception:
The method 'Skip' is only supported for sorted input in LINQ to Entities.
The method 'OrderBy' must be called before the method 'Skip'.
...I called OrderBy() (albeit Descending) and I called it before Skip()! What am I missing?
You haven't ordered the groups; you need to do that before you can page. For example:
.GroupBy(c => c.Reference).OrderBy(grp => grp.Key).Skip(x).Take(100);
(you can also substitute OrderByDescending if you want the groups in reverse order)
Also: since you are grouping, the order in the original data is largely meaningless; you could probably remove the OrderByDescending(c => c.TimeStamp).
So net result:
var query = container.CoinMessageSet.Where(
c => c.MessageState != MessageStateType.Closed &&
(c.DonorOperator.OperatorCode.Equals("opcode") ||
c.RecipientOperator.OperatorCode.Equals("opcode"))
).GroupBy(c => c.Reference).OrderBy(grp => grp.Key)
.Skip(x).Take(100);
or possibly:
var query = (from c in container.CoinMessageSet
where c.MessageState != MessageStateType.Closed &&
(c.DonorOperator.OperatorCode == "opcode" ||
c.RecipientOperator.OperatorCode == "opcode")
group c by c.Reference into grp
orderby grp.Key
select grp).Skip(x).Take(100);
It is most probably because of the GroupBy after the OrderByDescending.
I think you can try:
container.CoinMessageSet.Where(
c => c.MessageState != MessageStateType.Closed &&
(c.DonorOperator.OperatorCode.Equals("opcode") ||
c.RecipientOperator.OperatorCode.Equals("opcode"))
).OrderByDescending(c => c.TimeStamp)
.GroupBy(c => c.Reference).OrderByDescending(c = > c.Key).Skip(x).Take(100);
I'm using LINQ on an IQueryable returned from NHibernate and I need to select the row with the maximum value(s) in a couple of fields.
I've simplified the bit that I'm sticking on. I need to select the one row from my table with the maximum value in one field.
var table = new Table { new Row(id: 1, status: 10), new Row(id: 2, status: 20) }
from u in table
group u by 1 into g
where u.Status == g.Max(u => u.Status)
select u
This is incorrect but I can't work out the right form.
BTW, what I'm actually trying to achieve is approximately this:
var clientAddress = this.repository.GetAll()
.GroupBy(a => a)
.SelectMany(
g =>
g.Where(
a =>
a.Reference == clientReference &&
a.Status == ClientStatus.Live &&
a.AddressReference == g.Max(x => x.AddressReference) &&
a.StartDate == g.Max(x => x.StartDate)))
.SingleOrDefault();
I started with the above lambda but I've been using LINQPad to try and work out the syntax for selecting the Max().
UPDATE
Removing the GroupBy was key.
var all = this.repository.GetAll();
var address = all
.Where(
a =>
a.Reference == clientReference &&
a.Status == ClientStatus.Live &&
a.StartDate == all.Max(x => x.StartDate) &&
a.AddressReference == all.Max(x => x.AddressReference))
.SingleOrDefault();
I don't see why you are grouping here.
Try this:
var maxValue = table.Max(x => x.Status)
var result = table.First(x => x.Status == maxValue);
An alternate approach that would iterate table only once would be this:
var result = table.OrderByDescending(x => x.Status).First();
This is helpful if table is an IEnumerable<T> that is not present in memory or that is calculated on the fly.
You can also do:
(from u in table
orderby u.Status descending
select u).Take(1);
You can group by status and select a row from the largest group:
table.GroupBy(r => r.Status).OrderByDescending(g => g.Key).First().First();
The first First() gets the first group (the set of rows with the largest status); the second First() gets the first row in that group.
If the status is always unqiue, you can replace the second First() with Single().
Addressing the first question, if you need to take several rows grouped by certain criteria with the other column with max value you can do something like this:
var query =
from u1 in table
join u2 in (
from u in table
group u by u.GroupId into g
select new { GroupId = g.Key, MaxStatus = g.Max(x => x.Status) }
) on new { u1.GroupId, u1.Status } equals new { u2.GroupId, Status = u2.MaxStatus}
select u1;
What about using Aggregate?
It's better than
Select max
Select by max value
since it only scans the array once.
var maxRow = table.Aggregate(
(a, b) => a.Status > b.Status ? a : b // whatever you need to compare
);
More one example:
Follow:
qryAux = (from q in qryAux where
q.OrdSeq == (from pp in Sessao.Query<NameTable>() where pp.FieldPk
== q.FieldPk select pp.OrdSeq).Max() select q);
Equals:
select t.* from nametable t where t.OrdSeq =
(select max(t2.OrdSeq) from nametable t2 where t2.FieldPk= t.FieldPk)
Simply in one line:
var result = table.First(x => x.Status == table.Max(y => y.Status));
Notice that there are two action.
the inner action is for finding the max value,
the outer action is for get the desired object.