Linq to Sql: Add additional data to result

Question

Hi,

Bumped into a strange situation here. Trying to extract cars from a sql database within a certain range of a position (lat/long) and return an IQueryable to do additional logic on the resultset afterwards.

public IQueryable<Car> QueryAllCarsByDistance(float latitude, float longitude, int distance)
{
    var cars = from car in QueryAllCars()
               join i in sqlContext.QueryContactsByDistance(latitude, longitude, distance)
               on car.ContactId equals i.Id
               orderby i.Distance
               select car;

    return cars;
}

QueryContactByDistance beeing a function in the SQL database and QueryAllCars just returns all cars from database.

My question is now: How do I append the Distance (i.Distance) to car? I don't want to do a select new Car { Distance = i.Distance, Id = car.Id, ... }. But how to just append this additional value to the car object?

Answer 1

Unfortunately there is no way to do this. For most normal coding purposes, the type definitions emitted by C# and VB.Net are immutable. Fields and Properties cannot be added or removed from them at runtime.

All you can do is create a new type which wraps the Car type and provides the additional property. Or create an AnonymousType which has all of the properties needed.

Answer 2

One way around this is that you could setup a partial class for this (if you havn't already) add a new property to it called DistanceToReferencePoint, then in query set that property to distance, it then would not be saved in the database but would give you access to it.