Unable to read values into a List<ReferenceType> property using ClassMap

[enheh]

If I try to use a class map to read values into a List<ReferenceType> property,
with something like this:

public class CarFleet ()
{
    public List<Velocity> Cars { get; set; }
}

public class Velocity ()
{
    public float Speed { get; set; }
    public float Direction { get; set; }
}

internal class CarFleetMap : ClassMap<CarFleet>
{
    public CarFleetMap()
    {
        Map(m => m.Cars[0].Speed).Name("car1_speed");
        Map(m => m.Cars[1].Speed).Name("car2_speed");
        Map(m => m.Cars[0].Direction).Name("car1_direction");
        Map(m => m.Cars[1].Direction).Name("car2_direction");
    }
}

I get a runtime exception like this: "Property 'Single Speed' is not defined for type 'CarFleet'"

I've looked all through the test cases and can't seem to find anything analogous. Is there some way to make this work?

[AltruCoder]

A slight change to CarFleet may get you close to what you want.

public class CarFleet 
{
    public Velocity Car1 { get; set; }
    public Velocity Car2 { get; set; }
}

You can use ReferenceHeaderPrefix to register the prefix for car speed and direction. PrepareHeaderForMatch will allow you to ignore the case of your titles. Lastly, you can leave out the CarFleetMap class and just use AutoMap()

using (var stream = new MemoryStream())
using (var writer = new StreamWriter(stream))
using (var reader = new StreamReader(stream))
using (var csv = new CsvReader(reader))
{
    csv.Configuration.Delimiter = ",";
    writer.WriteLine("car1_speed,car1_direction,car2_speed,car2_direction");
    writer.WriteLine("45.2,56.3,35.2,64.1");
    writer.Flush();
    stream.Position = 0;

    csv.Configuration.ReferenceHeaderPrefix = (type, name) => $"{name}_";
    csv.Configuration.PrepareHeaderForMatch = (header, index) => header.ToLower();
    csv.Configuration.AutoMap<CarFleet>();
    var records = csv.GetRecords<CarFleet>();
}

[enheh]

Using ReferenceHeaderPrefix and PrepareHeaderForMatch is a nice trick, and I'll definitely keep that in mind! The code I presented here is just a simplified example to highlight the issue I'm encountering, though, and the real data structures are much more complicated requiring me to still use ClassMap.

Nonetheless, I can modify to the real version of CarFleet in the way you suggest as a workaround. It would definitely be preferable, however, to have some way of reading reference types into an array or list, not just for this case, but in general for other potentially more involved scenarios. Is that not possible?

[AltruCoder]

I am not the expert on this. I have been answering questions mainly to increase my own knowledge. There was an issue very similar to yours, but Josh only showed it was possible to map a single ReferenceType to the List. #837
It's a little messy, but using the ideas from that issue, I think I have what you are looking for.

public class CarFleet
{
    public int Id { get; set; }
    public string Name { get; set; }
    public List<Velocity> Cars { get; set; }
}

using (var stream = new MemoryStream())
using (var writer = new StreamWriter(stream))
using (var reader = new StreamReader(stream))
using (var csv = new CsvReader(reader))
{
    csv.Configuration.Delimiter = ",";
    writer.WriteLine("Id,Name,car1_speed,car1_direction,car2_speed,car2_direction");
    writer.WriteLine("1,name,45.2,56.3,35.2,64.1");
    writer.Flush();
    stream.Position = 0;

    var records = new List<CarFleet>();
    csv.Read();
    csv.ReadHeader();
    while (csv.Read())
    {
        var record = csv.GetRecord<CarFleet>();
        record.Cars = new List<Velocity>();
        Velocity car = null;

        for (var i = 2; i < csv.Context.HeaderRecord.Count(); i++)
        {
            if (i % 2 == 0)
            {
                car = new Velocity
                {
                    Speed = csv.GetField<float>(i)
                };
            } 
            else
            {
                car.Direction = csv.GetField<float>(i);
                record.Cars.Add(car);
            }
        }
        records.Add(record);
    }
}

[exiled78]

I admit I did not read the doco, but I did not realise the Property name casing had to match the headers.
csvReader.Configuration.PrepareHeaderForMatch = (header, index) => header.ToLower(); fixed my issue too.

[JoshClose]

@enheh Are there a set number of cars on each row, or does it vary?