David Huisman
asked on
LINQ return type for nested group query
I have the following query working in my code and now want to move into a separate class as a method that I call with List<Logrecord>, but having trouble determining what TYPE I need to return from the method.
recsByDate is a List<LogRecord> where records have Date, Time, EventType fields etc.
var vehicleGroupedByDate = from daterecs in recsByDate
where daterecs.Event == "Detection"
orderby daterecs.Date
group daterecs by daterecs.Date into vrecs
from vrecs2 in
(
from daterecs in vrecs
orderby daterecs.Time
group daterecs by daterecs.Vehicle
)
group vrecs2 by vrecs.Key;
recsByDate is a List<LogRecord> where records have Date, Time, EventType fields etc.
var vehicleGroupedByDate = from daterecs in recsByDate
where daterecs.Event == "Detection"
orderby daterecs.Date
group daterecs by daterecs.Date into vrecs
from vrecs2 in
(
from daterecs in vrecs
orderby daterecs.Time
group daterecs by daterecs.Vehicle
)
group vrecs2 by vrecs.Key;
Last Comment
ASKER
I tried using the suggested return type and get error
Error CS0266 Cannot implicitly convert type 'System.Collections.Generi
public IGrouping<DateTime, IGrouping<string, List<BodyGuardUserFriendly
{
var vehicleQuery = from daterecs in recsByDate
where daterecs.Event == "Detection"
orderby daterecs.Date
group daterecs by daterecs.Date into vrecs
from vrecs2 in
(
from daterecs in vrecs
orderby daterecs.Time
group daterecs by daterecs.Vehicle
)
group vrecs2 by vrecs.Key;
return vehicleQuery;
}
Error CS0266 Cannot implicitly convert type 'System.Collections.Generi
public IGrouping<DateTime, IGrouping<string, List<BodyGuardUserFriendly
{
var vehicleQuery = from daterecs in recsByDate
where daterecs.Event == "Detection"
orderby daterecs.Date
group daterecs by daterecs.Date into vrecs
from vrecs2 in
(
from daterecs in vrecs
orderby daterecs.Time
group daterecs by daterecs.Vehicle
)
group vrecs2 by vrecs.Key;
return vehicleQuery;
}
The error message gave you the type you were looking for:
IEnumerable<IGrouping<Date
When I tried it, I checked only the items type, so the IEnumerable was missing.
IEnumerable<IGrouping<Date
When I tried it, I checked only the items type, so the IEnumerable was missing.
ASKER
Changed to type as you suggest and get error
Severity Code Description Project File Line Suppression State
Error CS0266 Cannot implicitly convert type 'System.Collections.Generi
public IEnumerable<IGrouping<Date
GetVehicleDetections(List<
{
var vehicleQuery = from daterecs in recsByDate
where daterecs.Event == "Detection"
orderby daterecs.Date
group daterecs by daterecs.Date into vrecs
from vrecs2 in
(
from daterecs in vrecs
orderby daterecs.Time
group daterecs by daterecs.Vehicle
)
group vrecs2 by vrecs.Key;
return vehicleQuery;
}
Severity Code Description Project File Line Suppression State
Error CS0266 Cannot implicitly convert type 'System.Collections.Generi
public IEnumerable<IGrouping<Date
GetVehicleDetections(List<
{
var vehicleQuery = from daterecs in recsByDate
where daterecs.Event == "Detection"
orderby daterecs.Date
group daterecs by daterecs.Date into vrecs
from vrecs2 in
(
from daterecs in vrecs
orderby daterecs.Time
group daterecs by daterecs.Vehicle
)
group vrecs2 by vrecs.Key;
return vehicleQuery;
}
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ASKER
Thanks for your help
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Assuming that Date's type is DateTime and Vehicle's type is String, it should be:
IGrouping<DateTime, IGrouping<string, LogRecord>>