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)
};
Related
I have this service:
//seroiunoiweucroewr
///wercewrwerwerwer
//wcererewrwerwer
public List<UserRoleContract> GetRolePagesByUserId(long plngUserId, DisplayType displayType)
{
List<UserRoleContract> result = new List<UserRoleContract>();
using (CitiCallEntities context = new CitiCallEntities())
{
try
{
//var DisplayList = Utility.GetEnumDescriptions(typeof(DisplayType)).ToList();
//var selectValue = DisplayList.Where(i => i.Key == (byte) DisplayType.Windows).FirstOrDefault();
result = (from oUser in context.User
join oUserRole in context.UserRole on oUser.Id equals oUserRole.UserId
join oRoleRightsPage in context.RoleRightsPage.Where(i => i.IsActive == true)
on oUserRole.RoleId equals oRoleRightsPage.RoleId
join oApplicationPage in context.ApplicationPage.Where(i => i.IsActive == true)
on oRoleRightsPage.PageId equals oApplicationPage.Id
join oRole in context.Role on oUserRole.RoleId equals oRole.Id
join oEmployee in context.Employee on oUser.EmployeeId equals oEmployee.Id
join oSection in context.Section on oEmployee.SectionId equals oSection.Id
where oUser.IsActive == true && oUser.Id == plngUserId
&& oRole.IsActive == true && (((DisplayType)oRoleRightsPage.DisplayType).HasFlag(displayType))
//am getting error in has flag
// am having three display type web, windows and all
// how to overcome
select new UserRoleContract
{
UserId = oUser.Id,
RoleId = oRole.Id,
RoleName = oRole.RoleName,
PageID = oApplicationPage.Id,
PageName = oApplicationPage.PageName,
IsOPsCtrl = oRole.IsOPsCtrl,
ISOPsCtrlFor = oRole.OPsCtrlFor,
SectionId = oSection.Id,
DisplayType = oRoleRightsPage.DisplayType,
}).Distinct().ToList();
}
catch (Exception exception)
{
HandleExpcetion(exception);
//throw new CitiCallException(exception.Message);
}
}
return result;
}
I am getting Linq error in has flag conversion, how do I overcome this problem?
you are geeting error because HasFlag method is not paresent in database i.e. it might be part of language or local function in code which is not present in database.
So when query is translated it found this method is not available and that is the reason you are getting error.
one solution to avoid this error is
Brind all data from databae
Than filter than data, i.e. apply HasFlag method of it.
But this will bring all data and might decrease performance.
Example is
remove this line (((DisplayType)oRoleRightsPage.DisplayType).HasFlag(displayType) from your query
var list = querieddata //first fetch data without hasflag condition/method
.AsEnumerable() // Rest of the query in-process
.Where(oRoleRightsPage=> ((DisplayType)oRoleRightsPage.DisplayType).HasFlag(displayType))//apply condition here once fetching done
.ToList();
The HasFlag method has no equivalent in Linq to Entities which is why you get that error. You can get around it by using bitwise comparison instead of using HasFlag, for example this:
((DisplayType)oRoleRightsPage.DisplayType).HasFlag(displayType)
Becomes:
(oRoleRightsPage.DisplayType & displayType) > 0
I've got a class that contains a list item. I would like for a linq query to populate the class, including this list. Here is my query:
var query = from c in context.Cars
select new CarListItem()
{
ID = c.ID,
Make = c.Make,
AvailableColors = context.CarColors.Where(u => u.CarID == c.ID).ToList()
};
Basically, I want to get a list of all of the cars, including a list of the available colors for each respective car.
The problem is that the inclusion of .ToList() within the query results in an error: An error occurred:
LINQ to Entities does not recognize the method 'System.Collections.Generic.List`1[CarSystem.Models.CarColors] ToList[CarColors](System.Collections.Generic.IEnumerable`1[CarSystem.Models.CarColors])' method, and this method cannot be translated into a store expression.
At this point, I don't know whether I am just using wrong syntax within the Linq query (should I use something other than .ToList()?) or if maybe the architecture of the models is wrong.
You can't. EF tries to translate ToList() to SQL and doesn't know how.
You could project to another type, then call ToList():
var query = (from c in context.Cars
select new
{
ID = c.ID,
Make = c.Make,
AvailableColors = context.CarColors.Where(u => u.CarID == c.ID)
}).ToList()
.Select(c => new CarListItem()
{
ID = c.ID,
Make = c.Make,
AvailableColors = c.AvailableColors.ToList()
});
or change the type of CarListItem.AvailableColors to IEnumerable<CarColor>:
var query = from c in context.Cars
select new CarListItem()
{
ID = c.ID,
Make = c.Make,
AvailableColors = context.CarColors.Where(u => u.CarID == c.ID)
};
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 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 });
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
}