I'm implementing ASP.NET Core project and have a query like the following for finding count of distinct userId per operatorName, however it shows me error for the line count distinct after running the project:
var activeUserPerOperatorCount = requests.GroupBy(x => new { operatorName = x.Operator.Name, x.UserId }).Select(x => new
{
userIds = x.Key.UserId,
operatorNames = x.Key.operatorName,
activeUserPerOperatorCount = x.Select(l => l.UserId).Distinct().Count()
}).ToList();
I appreciate if anyone helps me how can I find distinct count of userId per operatorName in my query.
ok, the correct query is like the following and it works correctly:
var activeUserPerOperatorCount = requests.GroupBy(x => new { operatorName = x.Operator.Name}).Select(x => new
{
operatorNames = x.Key.operatorName,
activeUserPerOperatorCount = requests.Select(l => l.UserId).Distinct().Count()
}).ToList();
Related
So I have my View setup like this in the controller:
public ActionResult View(Guid projectID)
{
OnboardModel model = context.onboard_projectInfos.Where(x => x.projectID == projectID).Select(x =>
new OnboardModel()
{
propertymanagername = x.propertymanagername,
propertymanagercontactemail = x.propertymanagercontactemail,
date_modified = (DateTime)x.date_modified,
projectmanagercontactnumber = x.projectmanagercontactnumber,
Developer = x.onboard_projectCreate.Developer,
status1 = x.onboard_projectCreate.status1,
ProjectName = x.onboard_projectCreate.ProjectName
}).SingleOrDefault();
var pix = projectID.ToString();
context.onboard_BuildingInfos.Where(x => x.buildprojectID == pix).GroupBy(x => x.buildprojectID).Select(g => {
model.totalres = g.Sum(b => b.numberofres);
model.totalcom = g.Sum(b => b.numberofcommer);
});
return View(model);
}
Problem is grabbing the sum of numberofres and numberofcommer from BuildingInfos.
Using .Select gives me the error:
Error CS0411 The type arguments for method 'Queryable.Select(IQueryable, Expression>)' cannot be inferred from the usage. Try specifying the type arguments explicitly.
How to I write this LINQ statement correctly?
Thanks.
You cannot modify an object within a select (you can only create a new object). Further, you can't add new properties to an existing object.
We'll assume that OnboardModel defines the totalres and totalcom properties.
var query = context.onboard_BuildingInfos
.Where(x => x.buildprojectID == pix)
.GroupBy(x => x.buildprojectID);
foreach(var g in query)
{
model.totalres = g.Sum(b => b.numberofres);
model.totalcom = g.Sum(b => b.numberofcommer);
}
I have the following query that groups locations and the average item cost and I would like to write it as one query but I cannot figure out the syntax. What LINQ do I need to do this? I have tried writing it different ways but the syntax is not correct.
var joinedData =
from r in shops
join i in items on r.shopId equals i.shopId
select new
{
Region = r.Location,
ItemCost = i.ItemCost
};
var AverageCostByLocation = joinedData
.GroupBy(m => new { m.Location})
.Select(m => new
{
Location= m.Key.Location,
AverageItemCost = m.Average(x => x.ItemCost)
});
Well, if you put first expression in parenthesis it should allow to join both expressions as they are. Also I'd probably get rid of second anonymous type for perfomance reasons (the new { m.Location} line is redundant, you might want to use .Key instead) :
var AverageCostByLocation =
(from r in shops
join i in items on r.shopId equals i.shopId
select new
{
Region = r.Location,
ItemCost = i.ItemCost
})
.GroupBy(m => m.Location)
.Select(m => new
{
Location= m.Key,
AverageItemCost = m.Average(x => x.ItemCost)
});
As the title states, I'm trying to perform a select subquery in Linq-To-SQL. Here's my situation:
I have a database view which returns the following fields:
SourceId
LicenseId
LicenseName
CharacteristicId
CharacteristicName
Now I want to be able to store this in a model of mine which has the following properties
Id
Name
Characteristics (this is List which has Id, Name and Icon => Icon is byte[])
Here's the query I wrote which doesn't work:
var licensesWithCharacteristics =
_vwAllLicensesWithAttributesAndSourceIdRepository.GetAll()
.Where(x => x.SourceID == sourceId)
.Select(a => new LicenseWithCharacteristicsModel()
{
LicenseId = a.LicenseId,
LicenseName = a.LicenseName
,CharacteristicList = _vwAllLicensesWithAttributesAndSourceIdRepository.GetAll()
.Where(x => x.LicenseId == a.LicenseId)
.Select(c => new CharacteristicModel { Id = c.CharacteristicID, Name = c.CharacteristicName, Icon = c.Icon })
.Distinct().ToList()
})
.Distinct().ToList();
How would you solve this? I'm trying to do this in one query to keep my performance up, but I'm kind of stuck.
Your sample query and models are not that coherent (where does Icon come from, Characteristics or CharacteristicList), but anyway.
I do this in two parts, you can of course regroup this in one query.
I enumerate the result after the grouping, you may try to do without enumerating (all in linq to sql, but not sure it will work).
var groupedResult =
_vwAllLicensesWithAttributesAndSourceIdRepository.GetAll()
.Where(x => x.SourceID == sourceId)
.GroupBy(m => new {m.LicenseId, m.LicenseName})
.ToList();
var results = groupedResult.Select(group => new LicenseWithCharacteristicsModel {
LicenseId = group.Key.LicenseId,
LicenseName = group.Key.LicenseName,
Characteristics = group.Select(m=> new CharacteristicModel {
Id = m.CharacteristicId,
Name = m.CharacteristicName
}).ToList()
});
in "single query"
_vwAllLicensesWithAttributesAndSourceIdRepository.GetAll()
.Where(x => x.SourceID == sourceId)
.GroupBy(m => new {m.LicenseId, m.LicenseName})
.Select(group =>
new LicenseWithCharacteristicsModel
{
LicenseId = group.Key.LicenseId,
LicenseName = group.Key.LicenseName,
Characteristics = group.Select(m =>
new CharacteristicModel
{
Id = m.CharacteristicId,
Name = m.CharacteristicName
}).ToList()
});
I'm using LINQ to manipulate a datatable. I have 3 columns - I would like group by one and then select the remaining 2 columns together. At the moment I have something like this
var query = reportDataTable.AsEnumerable()
.GroupBy(c => c["Code"])
.Select(g =>
new {
Code = g.Key,
Rank = g.Select(f => new
{ f["rank"],
f["Name"]}).ToArray()
});
but I get issues due to anonymous types. I know this syntax would work if I could reference the the column headers directly (in say a list or w/e). How can I get around this with DataTables? Cheers.
Edit:
Well I'd like to be able to reference the fields later when I come to populate the data into a different datatable:
foreach (var q in query)
{
DataRow df = dp.NewRow();
df["Code"] = q.Code;
foreach (var rank in q.Rank)
{
df[rank.name] = rank.rank;
}
dp.Rows.Add(df);
}
define your Rank fields, Also if you have a class for it, call related class constructor,
you can see this in bellow code, before ToArray.
var query = reportDataTable.AsEnumerable()
.GroupBy(c => c["Code"])
.Select(g =>
new { Code = g.Key, Rank =
g.Select(f => new { rank = f["rank"], name = f["Name"]})
.ToArray() });
I have a Windows forms application (.NET 4.0) running with a Sql Server CE 3.5 database, which I access via an EF connection.
Here is my initial query, which returns two results:
var list = db.UserPresentation
.Select(up => new
{
UserPresentationID = up.UserPresentationID,
PresentationName = up.PresentationName,
DateRequested = up.DateRequested,
Edit = string.Empty,
Delete = string.Empty,
Download = string.Empty
})
.OrderByDescending(up => up.DateRequested)
.ToList();
Now I introduce an external variable and a where clause, and it returns zero results. If I run this same code in LinqPad, it returns 2 results.
int userID = 2;
// load list of user presentations
var list = db.UserPresentation
.Where(up => up.UserID == userID)
.Select(up => new
{
UserPresentationID = up.UserPresentationID,
PresentationName = up.PresentationName,
DateRequested = up.DateRequested,
Edit = string.Empty,
Delete = string.Empty,
Download = string.Empty
})
.OrderByDescending(up => up.DateRequested)
.ToList();
Now I hardcode the userid inside the query, and it returns two results again:
var list = db.UserPresentation
.Where(up => up.UserID == 2)
.Select(up => new
{
UserPresentationID = up.UserPresentationID,
PresentationName = up.PresentationName,
DateRequested = up.DateRequested,
Edit = string.Empty,
Delete = string.Empty,
Download = string.Empty
})
.OrderByDescending(up => up.DateRequested)
.ToList();
I'm really stumped. Any idea what's going on here?
Is UserID nullable?
If so be sure to do .Where(up => up.UserID.HasValue && up.UserID.Value == userID)
I had something similar with a nullable datetime once
Have you tried assigning the same hard coded value inside your variable? My guess is that the value in your variable is not found among your data, that is if you are sure that the variable name is correct.