How to set null the error message with Fluent Validation

Question

I'm using this Lib to validate my models, but if a mode is not properly assigned it returns a error message, I just want to retrieve the StatusCode but with no message.

RuleFor(x => x.Email).NotEmpty().EmailAddress().WithMessage("");

If I put a null or "" in the .WithMessage method I get an Exception!

Answer 1

It seems to me that if you want to return an empty error, then something is wrong with your architecture.

However, you can do it like this:

RuleFor(x => x.Email).NotEmpty().EmailAddress().WithMessage((_) => "");

Such a design can be useful if you don't know in advance what the error message should be. Like this:

string error = string.Empty;
RuleFor(x => x.SomeProperty)
    .Must(x =>
    {
        if (someСondition)
        {
            error = "error message 1";
            return false;
        }
        if (anotherСondition)
        {
            error = $"error message 2: {x.ToString()}";
            return false;
        }
        return true;
    })
    .WithMessage((_) =>
    {
        return error;
    });