I would like to add a condition to the below query based on another property
eg"and a.City=b.City" .How would I do it .
Currenty query
var result = firstCollection.Join(secondCollection,
a => a.CustomerId,
b => b.CustomerId, //TO ADD "and a.City=b.City"
GetDifferences)
.SelectMany(x => x)
.Where(x => x != null).ToList();
In sql I would do:
Select * from firstCollection a
INNER JOIN secondCollection B on a.CustomerId=b.CustomerId and a.city=b.city
many thanks for your suggestions
Use anonymous types:
var result = firstCollection.Join(secondCollection,
a => new { a.CustomerId, a.City }
b => new { b.CustomerId, b.City },
GetDifferences)
.SelectMany(x => x)
.Where(x => x != null).ToList();
Related
I am getting this error for the query below
Unable to create a constant value of type API.Models.PersonProtocol. Only primitive types or enumeration types are supported in this context
ppCombined below is an IEnumerable object of PersonProtocolType, which is constructed by concat of 2 PersonProtocol lists.
Why is this failing? Can't we use LINQ JOIN clause inside of SELECT of a JOIN?
var persons = db.Favorites
.Where(x => x.userId == userId)
.Join(db.Person, x => x.personId, y => y.personId, (x, y) =>
new PersonDTO
{
personId = y.personId,
addressId = y.addressId,
favoriteId = x.favoriteId,
personProtocol = (ICollection<PersonProtocol>) ppCombined
.Where(a => a.personId == x.personId)
.Select( b => new PersonProtocol()
{
personProtocolId = b.personProtocolId,
activateDt = b.activateDt,
personId = b.personId
})
});
This cannot work because ppCombined is a collection of objects in memory and you cannot join a set of data in the database with another set of data that is in memory. You can try instead to extract the filtered items personProtocol of the ppCombined collection in memory after you have retrieved the other properties from the database:
var persons = db.Favorites
.Where(f => f.userId == userId)
.Join(db.Person, f => f.personId, p => p.personId, (f, p) =>
new // anonymous object
{
personId = p.personId,
addressId = p.addressId,
favoriteId = f.favoriteId,
})
.AsEnumerable() // database query ends here, the rest is a query in memory
.Select(x =>
new PersonDTO
{
personId = x.personId,
addressId = x.addressId,
favoriteId = x.favoriteId,
personProtocol = ppCombined
.Where(p => p.personId == x.personId)
.Select(p => new PersonProtocol
{
personProtocolId = p.personProtocolId,
activateDt = p.activateDt,
personId = p.personId
})
.ToList()
});
In my case, I was able to resolve the issue by doing the following:
I changed my code from this:
var r2 = db.Instances.Where(x => x.Player1 == inputViewModel.InstanceList.FirstOrDefault().Player2 && x.Player2 == inputViewModel.InstanceList.FirstOrDefault().Player1).ToList();
To this:
var p1 = inputViewModel.InstanceList.FirstOrDefault().Player1;
var p2 = inputViewModel.InstanceList.FirstOrDefault().Player2;
var r1 = db.Instances.Where(x => x.Player1 == p1 && x.Player2 == p2).ToList();
Don't know if anyone searches for this.
I had the same problem. A select on the query and then doing the where (or join) and using the select variable solved the problem for me.
(problem was in the collection "Reintegraties" for me)
query.Select(zv => new
{
zv,
rId = zv.this.Reintegraties.FirstOrDefault().Id
})
.Where(x => !db.Taken.Any(t => t.HoortBijEntiteitId == x.rId
&& t.HoortBijEntiteitType == EntiteitType.Reintegratie
&& t.Type == TaakType))
.Select(x => x.zv);
hope this helps anyone.
I had this issue and what I did and solved the problem was that I used AsEnumerable() just before my Join clause.
here is my query:
List<AccountViewModel> selectedAccounts;
using (ctx = SmallContext.GetInstance()) {
var data = ctx.Transactions.
Include(x => x.Source).
Include(x => x.Relation).
AsEnumerable().
Join(selectedAccounts, x => x.Source.Id, y => y.Id, (x, y) => x).
GroupBy(x => new { Id = x.Relation.Id, Name = x.Relation.Name }).
ToList();
}
I was wondering why this issue happens, and now I think It is because after you make a query via LINQ, the result will be in memory and not loaded into objects, I don't know what that state is but they are in in some transitional state I think. Then when you use AsEnumerable() or ToList(), etc, you are placing them into physical memory objects and the issue is resolving.
It's worth adding, since the OP's code sample doesn't provide enough context to prove otherwise, but I received this error as well on the following code:
public RetailSale GetByRefersToRetailSaleId(Int32 refersToRetailSaleId)
{
return GetQueryable()
.FirstOrDefault(x => x.RefersToRetailSaleId.Equals(refersToRetailSaleId));
}
Apparently, I cannot use Int32.Equals in this context to compare an Int32 with a primitive int; I had to (safely) change to this:
public RetailSale GetByRefersToRetailSaleId(Int32 refersToRetailSaleId)
{
return GetQueryable()
.FirstOrDefault(x => x.RefersToRetailSaleId == refersToRetailSaleId);
}
Just add AsEnumerable() andToList() , so it looks like this
db.Favorites
.Where(x => x.userId == userId)
.Join(db.Person, x => x.personId, y => y.personId, (x, y).ToList().AsEnumerable()
ToList().AsEnumerable()
I am getting this error for the query below
Unable to create a constant value of type API.Models.PersonProtocol. Only primitive types or enumeration types are supported in this context
ppCombined below is an IEnumerable object of PersonProtocolType, which is constructed by concat of 2 PersonProtocol lists.
Why is this failing? Can't we use LINQ JOIN clause inside of SELECT of a JOIN?
var persons = db.Favorites
.Where(x => x.userId == userId)
.Join(db.Person, x => x.personId, y => y.personId, (x, y) =>
new PersonDTO
{
personId = y.personId,
addressId = y.addressId,
favoriteId = x.favoriteId,
personProtocol = (ICollection<PersonProtocol>) ppCombined
.Where(a => a.personId == x.personId)
.Select( b => new PersonProtocol()
{
personProtocolId = b.personProtocolId,
activateDt = b.activateDt,
personId = b.personId
})
});
This cannot work because ppCombined is a collection of objects in memory and you cannot join a set of data in the database with another set of data that is in memory. You can try instead to extract the filtered items personProtocol of the ppCombined collection in memory after you have retrieved the other properties from the database:
var persons = db.Favorites
.Where(f => f.userId == userId)
.Join(db.Person, f => f.personId, p => p.personId, (f, p) =>
new // anonymous object
{
personId = p.personId,
addressId = p.addressId,
favoriteId = f.favoriteId,
})
.AsEnumerable() // database query ends here, the rest is a query in memory
.Select(x =>
new PersonDTO
{
personId = x.personId,
addressId = x.addressId,
favoriteId = x.favoriteId,
personProtocol = ppCombined
.Where(p => p.personId == x.personId)
.Select(p => new PersonProtocol
{
personProtocolId = p.personProtocolId,
activateDt = p.activateDt,
personId = p.personId
})
.ToList()
});
In my case, I was able to resolve the issue by doing the following:
I changed my code from this:
var r2 = db.Instances.Where(x => x.Player1 == inputViewModel.InstanceList.FirstOrDefault().Player2 && x.Player2 == inputViewModel.InstanceList.FirstOrDefault().Player1).ToList();
To this:
var p1 = inputViewModel.InstanceList.FirstOrDefault().Player1;
var p2 = inputViewModel.InstanceList.FirstOrDefault().Player2;
var r1 = db.Instances.Where(x => x.Player1 == p1 && x.Player2 == p2).ToList();
Don't know if anyone searches for this.
I had the same problem. A select on the query and then doing the where (or join) and using the select variable solved the problem for me.
(problem was in the collection "Reintegraties" for me)
query.Select(zv => new
{
zv,
rId = zv.this.Reintegraties.FirstOrDefault().Id
})
.Where(x => !db.Taken.Any(t => t.HoortBijEntiteitId == x.rId
&& t.HoortBijEntiteitType == EntiteitType.Reintegratie
&& t.Type == TaakType))
.Select(x => x.zv);
hope this helps anyone.
I had this issue and what I did and solved the problem was that I used AsEnumerable() just before my Join clause.
here is my query:
List<AccountViewModel> selectedAccounts;
using (ctx = SmallContext.GetInstance()) {
var data = ctx.Transactions.
Include(x => x.Source).
Include(x => x.Relation).
AsEnumerable().
Join(selectedAccounts, x => x.Source.Id, y => y.Id, (x, y) => x).
GroupBy(x => new { Id = x.Relation.Id, Name = x.Relation.Name }).
ToList();
}
I was wondering why this issue happens, and now I think It is because after you make a query via LINQ, the result will be in memory and not loaded into objects, I don't know what that state is but they are in in some transitional state I think. Then when you use AsEnumerable() or ToList(), etc, you are placing them into physical memory objects and the issue is resolving.
It's worth adding, since the OP's code sample doesn't provide enough context to prove otherwise, but I received this error as well on the following code:
public RetailSale GetByRefersToRetailSaleId(Int32 refersToRetailSaleId)
{
return GetQueryable()
.FirstOrDefault(x => x.RefersToRetailSaleId.Equals(refersToRetailSaleId));
}
Apparently, I cannot use Int32.Equals in this context to compare an Int32 with a primitive int; I had to (safely) change to this:
public RetailSale GetByRefersToRetailSaleId(Int32 refersToRetailSaleId)
{
return GetQueryable()
.FirstOrDefault(x => x.RefersToRetailSaleId == refersToRetailSaleId);
}
Just add AsEnumerable() andToList() , so it looks like this
db.Favorites
.Where(x => x.userId == userId)
.Join(db.Person, x => x.personId, y => y.personId, (x, y).ToList().AsEnumerable()
ToList().AsEnumerable()
I've been puzzling over this problem all morning and can't figure out how to do it in C#.
My SQL query as follows:
select a.CourseID,
a.UserID
from audit a
inner join results r on a.UserID = r.UserID
inner join Course c on a.CourseID = c.CourseID
where c.CourseType = 9 and a.Guid = 'A123F123D123AS123123'
and a.Result = 'Passed' and r.Class = 'Maths'
group by a.CourseID, a.UserID
order by a.UserID
returns exactly what I want, but I can't seem to translate it into linq format. (the format being used here is what is required in my job at the moment so please advise on this format)
So far I have the following:
var audits = auditRepository.Get(a => a.Course.CourseType == 9 && a.GUID == this.Company.GUID && a.Result == "Passed", null, null,
a => a.Course, a => a.User)
.Join(resultsRepository.Get(r => r.GUID == this.Company.GUID && r.Class == class),
a => a.UserID,
r => r.UserID,
(a, r) => new Audit
{
User = a.User,
Course = a.Course,
Result = a.Result,
Timestamp = a.Timestamp,
AuditID = a.AuditID,
UserID = a.UserID
}
)
.OrderByDescending(o => o.Timestamp)
.GroupBy(u => new { u.User, u.Course })
.Select(grp => grp.ToList())
.ToList();
However this returns duplicates.
Any advice is appreciated, thanks
H
Instead of
.Select(grp => grp.ToList())
Select only the first element from each group to exclude duplicates:
.Select(grp => grp.First())
If you need a count also:
.Select(t => new{grp = t.First(),cnt = t.Count()} )
Fix:
.Select(t => new { grp = t.First(), cnt = t.Select(s => s.AuditID).Distinct().Count() })
I'm trying to convert the following SQL expression into a Lambda LINQ query and I seem to be going round in circles at the moment:
select m.MemberExternalPK FROM Member.Member AS m INNER JOIN Member.Account AS a ON m.MemberID = a.MemberID where m.MemberExternalPK in
(
SELECT m.MemberExternalPK
FROM Member.Member AS m INNER JOIN Member.Account AS a ON m.MemberID = a.MemberID
group by MemberExternalPK
having Count(AccountID) = 1
)
and AccountStatusID = 3
So far I have managed to get the following syntax that returns the correct number of rows I am after but all columns (except the MemberExternalPK one I want)!
Members.Join(Accounts, m => m.MemberID, a => a.MemberID, (m, a) => new { m, a })
.GroupBy(t => t.m.MemberExternalPK, t => t.a)
.Where(grp => grp.Count(p => p.AccountID != null) == 1)
.SelectMany(sublist => sublist).Where(x => x.AccountStatusID == 3)
I think this is fairly close:
var query =
from m in Member_Member
join a in Member_Account on m.MemberID equals a.MemberID
group a by m.MemberExternalPK into gas
where gas.Count(ga => ga.AccountID != null) == 1
from ga in gas
where ga.AccountStatusID == 3
select gas.Key;
The only concern is the ga.AccountID != null which means that the gas group may have more than one record so you might end up with more than one gas.Key at the end.
Something like this? Splitting it up could also improve performance.
var externalMembers =
Members.Join(Accounts, m => m.MemberID, a => a.MemberID, (m, a) => new { m, a })
.GroupBy(grp => grp.MemberExternalPK)
.Where(grp => grp.Count() > 1)
.Select(grp => grp.Key);
var result =
Members.Where(w => externalMembers.Contains(w.MemberExternalPK) && w.AccountStatusID == 3)
.Select(s => s.MemberExternalPK)
I am getting this error for the query below
Unable to create a constant value of type API.Models.PersonProtocol. Only primitive types or enumeration types are supported in this context
ppCombined below is an IEnumerable object of PersonProtocolType, which is constructed by concat of 2 PersonProtocol lists.
Why is this failing? Can't we use LINQ JOIN clause inside of SELECT of a JOIN?
var persons = db.Favorites
.Where(x => x.userId == userId)
.Join(db.Person, x => x.personId, y => y.personId, (x, y) =>
new PersonDTO
{
personId = y.personId,
addressId = y.addressId,
favoriteId = x.favoriteId,
personProtocol = (ICollection<PersonProtocol>) ppCombined
.Where(a => a.personId == x.personId)
.Select( b => new PersonProtocol()
{
personProtocolId = b.personProtocolId,
activateDt = b.activateDt,
personId = b.personId
})
});
This cannot work because ppCombined is a collection of objects in memory and you cannot join a set of data in the database with another set of data that is in memory. You can try instead to extract the filtered items personProtocol of the ppCombined collection in memory after you have retrieved the other properties from the database:
var persons = db.Favorites
.Where(f => f.userId == userId)
.Join(db.Person, f => f.personId, p => p.personId, (f, p) =>
new // anonymous object
{
personId = p.personId,
addressId = p.addressId,
favoriteId = f.favoriteId,
})
.AsEnumerable() // database query ends here, the rest is a query in memory
.Select(x =>
new PersonDTO
{
personId = x.personId,
addressId = x.addressId,
favoriteId = x.favoriteId,
personProtocol = ppCombined
.Where(p => p.personId == x.personId)
.Select(p => new PersonProtocol
{
personProtocolId = p.personProtocolId,
activateDt = p.activateDt,
personId = p.personId
})
.ToList()
});
In my case, I was able to resolve the issue by doing the following:
I changed my code from this:
var r2 = db.Instances.Where(x => x.Player1 == inputViewModel.InstanceList.FirstOrDefault().Player2 && x.Player2 == inputViewModel.InstanceList.FirstOrDefault().Player1).ToList();
To this:
var p1 = inputViewModel.InstanceList.FirstOrDefault().Player1;
var p2 = inputViewModel.InstanceList.FirstOrDefault().Player2;
var r1 = db.Instances.Where(x => x.Player1 == p1 && x.Player2 == p2).ToList();
Don't know if anyone searches for this.
I had the same problem. A select on the query and then doing the where (or join) and using the select variable solved the problem for me.
(problem was in the collection "Reintegraties" for me)
query.Select(zv => new
{
zv,
rId = zv.this.Reintegraties.FirstOrDefault().Id
})
.Where(x => !db.Taken.Any(t => t.HoortBijEntiteitId == x.rId
&& t.HoortBijEntiteitType == EntiteitType.Reintegratie
&& t.Type == TaakType))
.Select(x => x.zv);
hope this helps anyone.
I had this issue and what I did and solved the problem was that I used AsEnumerable() just before my Join clause.
here is my query:
List<AccountViewModel> selectedAccounts;
using (ctx = SmallContext.GetInstance()) {
var data = ctx.Transactions.
Include(x => x.Source).
Include(x => x.Relation).
AsEnumerable().
Join(selectedAccounts, x => x.Source.Id, y => y.Id, (x, y) => x).
GroupBy(x => new { Id = x.Relation.Id, Name = x.Relation.Name }).
ToList();
}
I was wondering why this issue happens, and now I think It is because after you make a query via LINQ, the result will be in memory and not loaded into objects, I don't know what that state is but they are in in some transitional state I think. Then when you use AsEnumerable() or ToList(), etc, you are placing them into physical memory objects and the issue is resolving.
It's worth adding, since the OP's code sample doesn't provide enough context to prove otherwise, but I received this error as well on the following code:
public RetailSale GetByRefersToRetailSaleId(Int32 refersToRetailSaleId)
{
return GetQueryable()
.FirstOrDefault(x => x.RefersToRetailSaleId.Equals(refersToRetailSaleId));
}
Apparently, I cannot use Int32.Equals in this context to compare an Int32 with a primitive int; I had to (safely) change to this:
public RetailSale GetByRefersToRetailSaleId(Int32 refersToRetailSaleId)
{
return GetQueryable()
.FirstOrDefault(x => x.RefersToRetailSaleId == refersToRetailSaleId);
}
Just add AsEnumerable() andToList() , so it looks like this
db.Favorites
.Where(x => x.userId == userId)
.Join(db.Person, x => x.personId, y => y.personId, (x, y).ToList().AsEnumerable()
ToList().AsEnumerable()