Fluent validation in different date format in c#

If you need to handle different date formats using Fluent Validation, you can create a custom validator that checks the input string against multiple date formats and succeeds if any of them match. Here's how you can do it: 

using FluentValidation;
using System;

public class MyModelValidator : AbstractValidator(MyModel) --- Mymodel should be in angle bracket
{
    public MyModelValidator()
    {
        RuleFor(x => x.DateString)
            .Must(BeValidDate)
            .WithMessage("Invalid date format. Please provide a valid date in ISO 8601 format.");
    }

    private bool BeValidDate(string dateStr)
    {
        // Try to parse the date using the expected format (ISO 8601)
        return DateTime.TryParseExact(dateStr, "yyyy-MM-ddTHH:mm:ss.fffZ", null, System.Globalization.DateTimeStyles.None, out _);
    }
}

public class MyModel
{
    public string DateString { get; set; }
}

using FluentValidation;
using System;

public class MyModelValidator : AbstractValidator(MyModel) --- Mymodel should be in angle bracket
{
    public MyModelValidator()
    {
        RuleFor(x => x.DateString)
            .Must(BeValidDate)
            .WithMessage("Invalid date format. Please provide a valid date in one of the supported formats.");
    }

    private bool BeValidDate(string dateStr)
    {
        // Define an array of supported date formats
        string[] dateFormats = { "yyyy-MM-ddTHH:mm:ss.fffZ", "yyyy-MM-ddTHH:mm:ssZ", "MM/dd/yyyy", "dd/MM/yyyy" };

        // Try to parse the date using each format
        foreach (var format in dateFormats)
        {
            if (DateTime.TryParseExact(dateStr, format, null, System.Globalization.DateTimeStyles.None, out _))
            {
                // If parsing succeeds with any format, return true
                return true;
            }
        }

        // If parsing fails with all formats, return false
        return false;
    }
}

public class MyModel
{
    public string DateString { get; set; }
}