I am having a problem trying to group a small linq query.
The query excutes ok however no grouping happens. I assume its due to having 3 different fields I am trying to group.
var data = (from d in All()
group d by new { d.CustomerNumber, d.TransactionAmount, d.CustomerName }
into g
orderby g.Key.CustomerName
select new TransactionViewModel
{
CustomerNumber = g.Key.CustomerNumber,
TransactionAmount = g.Sum(s=>s.TransactionAmount),
CustomerName = g.Key.CustomerName
});
Ideally I would like to be able to return the grouped data with access to the 3 fields.
What do I need to modify?
Are you sure you have to do group d by new { d.CustomerNumber, d.TransactionAmount, d.CustomerName }
I just removed TransactionAmount from group by as it is diffrent for each row.
TRy this.
(from d in All() group d by new { d.CustomerNumber, d.CustomerName } into g orderby g.Key.CustomerName select new Test { CustomerNumber = g.Key.CustomerNumber, TransactionAmount = g.Sum(s => s.TransactionAmount), CustomerName = g.Key.CustomerName });
Related
I have a many-to-many relation and I'm trying to create the query which will fetch me the left side and a property which counts the number of records which are refferecend by it.
following is my query
var dbSet = await (from user in _dbContext.Users
where (from courseUsers in _dbContext.CourseUsers select courseUsers.UserId).Contains(user.Id)
select new
{
Name = user.Name,
Id = user.Id,
CourseUsersCount = _dbContext.CourseUsers.Where(item => item.UserId == user.Id).Count()
})
.ToListAsync();
What I don't like is how CourseUsersCount is computed. I would also like to include the total count property and the way I would do it is to add another property on the select which would just do a count over the _dbContext.CourseUsers and after that do another in-memory transformation.
I the end I would like a result with this structure to be created
{
count: 1000,
data: [{
Id: 1,
Name: "c",
CourseUsersCount: 2
}]
}
and I want to know how can I do this directly using linq-to-sql.
As mentioned in comments you have to use GroupBy for such calculation:
var query
from user in _dbContext.Users
from courseUsers in user.Courses
group user by new { user.Id, user.Name } into g
select new
{
g.Key.Id,
g.Key.Name,
CourseUsersCount = g.Count()
};
You need a Group By to merge all the CourseUsers into a single set, followed by a Join to attach the Users to it.
from course in _dbContext.CourseUsers // outer sequence
group course by course.UserId into courseGrp
join user in _dbContext.Users //inner sequence
on courseGrp.Key equals user.UserId// key selector
select new { // result selector
CourseUsersCount = courseGrp.Count(),
user.Name,
user.Id
};
When calling the query.ToList() I get
object reference not set to an instance of an object
For x.Gallons, all the orders have this value set, it's not null. Also, there are 2 DProducts in the database table with proper ID. What could be wrong?
ProductSummaryCollection.Clear();
var query = from p in Repository.repository.ctx.DProduct
join fo in Repository.repository.ctx.DFuelOrder.Include("DProduct")
on p.ID equals fo.DProductID
group fo by fo.DProduct into Prod
select new DProductSummary
{
Product = fo.DProduct,
TotalGallons = (float)Prod.Sum(x => x.Gallons)
};
try
{
IList<DProductSummary> ps = query.ToList();
foreach (DProductSummary dps in ps)
ProductSummaryCollection.Add(dps);
}
catch (Exception exc)
{
}
It seems that you can't do the following 2 things:
Create a entity object, DProduct in my case inside a linq query
You cannot access a reference in a linq query even if you Include it
So you have to use the join table.Propery instead.
A working query:
var query = from fo in Repository.repository.ctx.DFuelOrder.Include("DProduct")
join p in Repository.repository.ctx.DProduct
on fo.DProductID equals p.ID
group fo by new { fo.DProductID, p.Name } into Prod
select new DProductSummary
{
ProductName = Prod.Key.Name,
TotalGallons = (float)Prod.Sum(x => x.Gallons)
};
I am trying to show multiple records from database in datagridview but I'm having only a single record all the time.
2 tables are involved in this query, from 1st table I acquire all the id's those fulfill the condition and from 2nd table I am getting the user information.
1st table is tblUsers_Roles and 2nd is tblUsers.
These tables have primary/foriegn key relationship.
Here is my code:
IEnumerable<tblUsers_Role> id = db.tblUsers_Role.Where(a => a.User_Role == selectRole);
foreach (var user in id)
{
var userinfo = from b in db.tblUsers
where b.User_Id == user.User_Id
select new { b.First_Name, b.Last_Name, b.Status, b.Authenticated };
dgvResults.DataSource = userinfo.ToList();
dgvResults.Show();
}
You are assigning the grid in the loop. That is not going to work. Maybe something like this will work:
var userinfo =(from ur in db.tblUsers_Role
join u in db.tblUsers
on ur.User_Id equals u.User_Id
where ur.User_Role == selectRole
select new
{
u.First_Name,
u.Last_Name,
u.Status,
u.Authenticated
}).ToList();
dgvResults.DataSource = userinfo;
dgvResults.Show();
Or a alteretive would be like this:
var roles=db.tblUsers_Role
.Where(a => a.User_Role == selectRole)
.Select (a =>a.User_Id).ToList();
var userinfo=
(
from u in db.tblUsers
where roles.Contains(u.User_Id)
select new
{
u.First_Name,
u.Last_Name,
u.Status,
u.Authenticated
}
).ToList();
dgvResults.DataSource = userinfo;
dgvResults.Show();
Not as nice as the first one. But maybe you understand the concept.
I am new to using LINQ, right now i have a query in sql with multiple inner joins and it works fine. I am trying to change this to a equivalent LINQ code, i could able to implement LINQ except for the Distinct fact i am using in my query...
my query
select DT.[Name], count(distinct([FeatureControlID])) as [Value], DT.[Weight]
from [DocumentTypes] DT inner join
[DocumentTypesSchema] DTS on
DT.[ID] = DTS.[DocumentTypeID] inner join
ProductsFeaturesControlsDocumentValues [PFCDV] on
DTS.[ID] = PFCDV.[SchemaID]
where [PFCDV].[ProductID] = 72
group by DT.[Name], DT.[Weight], [DT].[ID]
order by [DT].[ID]
and my LINQ without the Distinct condition is as below
from dt in db.DocumentTypes
join dts in db.DocumentTypesSchemas on new { ID = dt.ID } equals new { ID = dts.DocumentTypeID }
join pfcdv in db.ProductsFeaturesControlsDocumentValues on new { ID = dts.ID } equals new { ID = pfcdv.SchemaID }
where
pfcdv.ProductID == 72
group new {dt, pfcdv} by new {
dt.Name,
dt.Weight,
dt.ID
} into g
orderby
g.Key.ID
select new {
g.Key.Name,
Value = (Int64?)g.Count(p => p.pfcdv.FeatureControlID != null),
Weight = (System.Decimal?)g.Key.Weight
}
can anyone give me a hand on this? actually the linq code executes without the Distinct feature i used in the code.
Have you tried something like this?
...
select new {
g.Key.Name,
Value = (Int64?)g.Select(p => p.pfcdv.FeatureControlID)
.Where(id => id != null)
.Distinct().Count()
Weight = (System.Decimal?)g.Key.Weight
}
from teamBudget in TeamBudgets
where teamBudget.TeamID == 71002
join teamBroker in TeamBrokers on 71002 equals teamBroker.TeamID
join goal in Goals on teamBroker.GlobalBrokerID equals goal.GlobalBrokerID
group goal by goal.GlobalBrokerID into g
select new
{
// TeamID=teamBroker.TeamID,
// MTDGoal=teamBudget.Sum(t => t.Budget),
RevenueMTDCurrent = g.Sum(x => x.RevenueMTDCurrent)
}
Commented part is a problem. How to access any data that is not contained in grouped element?
you need to Group multiple fields then only you can access that data.
like
var result = from i in
(from uh in db.UserHistories
where uh.User.UserID == UserID && uh.CRMEntityID == (int)entity
select new { uh.ActionID, uh.ActionType, uh.ObjectID })
group i by new { i.ActionID, i.ActionType, i.ObjectID } into g
select new { g.ActionID, g.ActionType, g.ObjectID };
Hope this will help