Linq - Include and filter - nested collections - asp.net-mvc

Question

I'm working on a mvc application where people can search for train routes. I made my database code-first with the entity framework but i cant seem to figure out how to ask some more complex queries.
I have a collection of routes which i use in my viewmodel. So the first step is asking which routes have a certain start and end station. Then i want to include the schedule where a certain day is set on true (and where the start and end date of that schedule match). This is linked to a collection of trips (i am using this table cause routes run multiple times on a day). From here i can find all the matching stations with the arrive and depart hours from the table routeHasStations.
So i was thinking something like:
public IEnumerable<Route> Search(DateTime date, int? departure, int? arrival)
{
var day = date.DayOfWeek.ToString();
return db.Routes.Where(r => r.DepartureStationID == departure && r.ArrivalStationID == arrival)
.Include(s => s.Train)
//using linq.dynamic here
.Include(r => r.Schedule.where(day + "==" + true)
.Include(sch => sch.trip.where(date > sch.DepartureTime)
.Include(route => route.RouteHaseStations)
.Include(st => st.Stations)
}
But this is offcourse not working. Here are my models:
public class Route
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int RouteID { get; set; }
public String RouteName { get; set; }
[ForeignKey("Train")]
public int TrainID { get; set; }
[ForeignKey("Station")]
public int DepartureStationID { get; set; }
[ForeignKey("Station")]
public int ArrivalStationID { get; set; }
public virtual ICollection<Schedule> Schedule { get; set; }
public virtual Train Train { get; set; }
public virtual Station DepartureStation { get; set; }
public virtual Station ArrivalStation { get; set; }
}
public class Station
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int StationID { get; set; }
[Display(Name = "Station")]
public String Name { get; set; }
public int Platforms { get; set; }
public float Latitude { get; set; }
public float Longitude { get; set; }
public virtual ICollection<RouteHasStation> RouteHasStation { get; set; }
}
public class Train
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int TrainID { get; set; }
public String Name { get; set; }
public virtual ICollection<Route> Route { get; set; }
}
public class Schedule
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int ScheduleID { get; set; }
[ForeignKey("Route")]
public int RouteID { get; set; }
public Boolean Monday { get; set; }
public Boolean Tuesday { get; set; }
public Boolean Wednesday { get; set; }
public Boolean Thursday { get; set; }
public Boolean Friday { get; set; }
public Boolean Saturday { get; set; }
public Boolean Sunday { get; set; }
public DateTime? StartDate { get; set; }
public DateTime? EndDate { get; set; }
public virtual ICollection<Trip> Trip { get; set; }
public virtual Route Route { get; set; }
}
public class Trip
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int TripID { get; set; }
[ForeignKey("Schedule")]
public int ScheduleID { get; set; }
public DateTime DepartureTime { get; set; }
public virtual ICollection<RouteHasStation> RouteHasStation { get; set; }
}
public class RouteHasStation
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int RouteHasStationID { get; set; }
[ForeignKey("Station")]
public int StationID { get; set; }
public virtual Station Station { get; set; }
[ForeignKey("Trip")]
public int TripID { get; set; }
public virtual Trip Trip { get; set; }
[DataType(DataType.Time)]
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:HH:mm}")]
public DateTime? Arrival { get; set; }
[DataType(DataType.Time)]
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:HH:mm}")]
public DateTime? Departure { get; set; }
public int Platform { get; set; }
public float Distance { get; set; }
}

Answer 1

Apart from your typing errors, your program has several problems.
The statement
.Include(r => r.Schedule.where(day + "==" + true)
does not have a correct predicate. Even if you'd be able to change it into a predicate LINQ to SQL doesn't know how to handle this as a query, because you need to call a different procedure from your Schedule class depending on variable day.
Because of the combination with the include, I'm not sure what you want. From your description I'd say you want all routes (with a certain departure station and arrival station) that are scheduled to run on the given search date.
I'm not sure if you are using an existing database, or are still developing it. In the latter case, consider changing the Schedule class such that Schedule is a flagged enum like this
[Flags]
public enum MyDayOfWeek
{
Sunday = 1 << System.DayOfWeek.Sunday, // 0x01
Monday = 1 << System.DayOfWeek.Monday, // 0x02
Tuesday = 1 << System.DayOfWeek.Tuesday, // 0x04
Wednesday 1 << System.DayOfWeek.Wednesday, // 0x08
Thursday 1<< System.DayOfWeek.Thursday, // 0x10
Friday = 1 << System.DayOfWeek.Friday, // 0x20
Saturday = 1 << System.DayOfWeek.Saturday, // 0x40
}
public class Schedule
{
public int ScheduleID { get; set; }
public int RouteID { get; set; }
public MyDayOfWeek RunDays { get; set; }
public virtual ICollection<Trip> Trips {get; set;}
...
RunDays is an or-flagged variable of all days the route is scheduled to be run, for instance, if scheduled to run in weekends only:
RunDays = DayOfWeek.Saturday | DayOfWeek.Sunday;
The query to get all routes that are scheduled to run on a given DateTime will be like:
System.DayOfWeek dayOfWeek = day.DayOfWeek;
MyDayOfWeek myDayOfWeek = (MyDayOfWeek)( 1 << (int)dayOfWeek);
var routesRunningOnDate = db
.Where(route => route.DepartureStation etc
&& (route.RunDays & myDayOfWeek) == myDayOfWeek)
Linq to SQL will know how to handle it.
If you can't change the model of your database and you are stuck with this definition of Schedule, you can't perform it AsQueryable, however it will be possible to perform it AsEnumerable, in your local memory.
If you want to check if your route is scheduled on a certain day of week using the functions Schedule.Monday, Schedule.Tuesday, etc, I'd advise you define and extension for your Schedule class:
public static class ScheduleExtensions
{
// returns whether schedule scheduled on date:
public static bool IsScheduled(this Schedule schedule, DateTime date)
{
switch (date.DayOfWeek)
{
case DayOfWeek.Sunday:
return schedule.Sunday;
case DayOfWeek.Monday:
return chedule.Monday;
...
}
}
}
Usage:
db.Routes.AsEnumerable().Where (route => route.Schedule.IsScheduled(date));
Furthermore, it seems you haven't bracketed all your includes correctly. all your paramertes r, s, sch, route, st are all expected to be routes, while in fact you mean your sch to be Schedules, etc.
Be aware, that as long as you don't really enumerate over your sequence (and you don't dispose your DbContext), you don't need the Include statements. Include statements are needed when you don't specifically ask for a value, but you want them in local memory.
If you have an IQueryable, that does not use a certain field of your table and late you use this field, before you enumerate it, the field is automatically added to the query and thus to your SQL query:
var query1 = routes.Where(r.DepartureStationID == departure && r.ArrivalStationID == arrival);
var query2 = query1.Where(route => route.Schedule.Trips...)
Without the extra include LINQ to SQL knows that a join with the Schedule table is needed.
I guess you want the following routes:
(1) All routes that start on DepartureStation and arrive on ArrivalStation
(2) AND that are scheduled to run on day
(3) AND that are scheduled after (not on?) Schedule.DepartureTime
(4) Make sure you have all stations from route.RouteHasStations
Not really sure if Schedule.DepartureTime means the first day that this schedule is valid (so wouldn't ActivationDate be a better name?) or whether DepartureTime is the time that the train departs on the Scheduled dates.
In the latter case the statement
.Include(sch => sch.trip.where(date > sch.DepartureTime)
doesn't do what you want: it returns all schedules that were schedule on dates after your date, even if the departuretime is later than the time in your date
db.Routes.Where(route => route.DepartureStaionId == departure
&& route.ArrivalStationId == arrival
&& route.Schedule.IsScheduled(date)
&& date > route.Trips.DepartureTime)
// you don't need to include Schedule and Trips explicitly
// unless you need their fields outside this query
.Include(route => route.Train)
.Include(route => route.HasTrips)
// only include these if you need their fields outside this query
// if the only thing from train you want is Train.Name,
// use route.Train.Name in a select after the Where