Fluent Validation use of LINQ let?

Question

I'm trying to create a validation rule whereby I can pass in two parameters into a method called by Must()

My models;

public class Make
{
    public int MakeId { get; set; }
    public string Name { get; set; }
    public Car[] Cars { get; set; }
}

public class Car
{
    public int CarId { get; set; }
    public string Name { get; set; }
}

Validator

public class MakeValidator : AbstractValidator<Make>
{
    public MakeValidator()
    {
        When(car => car.Cars != null && car.Cars.Any(), () =>
        {               
            RuleFor(car => car.Car)
                .Must(car => ValidateCar(car.CarId, MakeId)
                .WithMessage("Invalid Car");
        });
    }

    public bool ValidateCar(Car[] Cars, int makeId)
    {
        foreach (var car in Cars)
        {
            // *** internal logic ***
        }
        return true;
    }
}

@lc "can we grab the CardId here? this line will break", but still, poorly formatted question. — Adam Houldsworth, Jul 11 '14 at 13:24
@wonea I'd suggest removing the question from code comments and make it more explicit, perhaps demonstrate it working with the LINQ query syntax (if it does at all), or any attempts you have made and why they didn't work. — Adam Houldsworth, Jul 11 '14 at 13:25
@AdamHouldsworth Agreed, I've revised the question. Should have taken lunch before hammering it out. — wonea, Jul 11 '14 at 14:14
@wonea Unfortunately, it looks like you've actually removed the question... — Adam Houldsworth, Jul 11 '14 at 14:18

Raphaël Althaus · Accepted Answer · 2014-07-11T13:36:37.087

1

use

Must((y, x) =>

instead of

Must(x =>

where y represents your class, and x your property

so to make things clearer

.Must((car, make) => ValidateCarMake(make, car.CarId)

EDIT

from the signature of your ValidateCarMake method, it should be

either

RuleFor(car => car.Makes)
     .Must((car, make) => ValidateCarMake(make, car.CarId)
     .WithMessage("Invalid Car Make");

or

RuleFor(car => car.Make)
      .Must((car, make) => ValidateCarMake(car.Makes, car.CarId)
      .WithMessage("Invalid Car Make");

edited Jul 11 '14 at 13:36

answered Jul 11 '14 at 13:30

Raphaël Althaus

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Thanks for answering my confusing question with a clear answer. Very much appreciated. Great insight. – wonea Jul 11 '14 at 14:13

Fluent Validation use of LINQ let?

1 Answers1