Regex Position exactly

Question

Hello again...
Now I need that help me, please.
I need to find a regular expression that:
The column id = 9 numerics digits and the third digit = 0 or 3.
I try but don't can
'grep -E '^[[:digit:]]{9}' athletesv2.csv'

Only can to limit to 9 Digits

thank you

Answer 1

Consider using data annotations using a custom rule. Below I show validating a single entity, to validate a list, simple loop through the list and if validating on the fly the code allows var isValid = new ValidKeyAttribute().IsValid(value); where value is the number to validate.

/// <summary>
/// Custom rule for third digit
/// </summary>
public class ValidKeyAttribute : ValidationAttribute
{
    public override bool IsValid(object sender)
    {
        string value = Convert.ToString(sender);

        if (value.Length < 9)
        {
            return false;
        }

        return value[2] == '0' || value[2] == '3';
    }
}

Using the following model to validate (below)

public class Athlete
{
    [ValidKey]
    [Required(ErrorMessage = "{0} is required")]
    public int Id { get; set; }
    [Required(ErrorMessage = "{0} is required")]
    [MaxLength(15)]
    public string FirstName { get; set; }
    [Required(ErrorMessage = "{0} is required")]
    [MaxLength(20)]
    public string LastName { get; set; }
    public override string ToString() => $"{FirstName} {LastName}";
}

Unit test

[TestClass]
public partial class ValidKeyTests : TestBase
{
    [TestMethod]
    [TestTraits(Trait.Annotations)]
    public void ValidKeyTest()
    {
        // arrange
        int value = 123456789;
        Athlete athlete = new () { Id = value, FirstName = "Jim", LastName = "Adams" };

        // act
        EntityValidationResult result = Model.Validate(athlete);

        // assert
        Check.That(result.IsValid).IsTrue();

    }
    [TestMethod]
    [TestTraits(Trait.Annotations)]
    public void NotValidBadIdKeyTest()
    {
        // arrange
        int value = 126456789;
        Athlete athlete = new() { Id = value, FirstName = "Jim", LastName = "Adams" };

        // act
        EntityValidationResult result = Model.Validate(athlete);

        // assert
        Check.That(result.IsValid).IsFalse();

    }

    [TestMethod]
    [TestTraits(Trait.Annotations)]
    public void NotValidNoIdKeyTest()
    {
        // arrange
        Athlete athlete = new() { FirstName = "Jim", LastName = "Adams" };
        // act
        EntityValidationResult result = Model.Validate(athlete);
        // assert
        Check.That(result.IsValid).IsFalse();

    }
}

And we can shortcut the above with var isValid = new ValidKeyAttribute().IsValid(value);

All source, C# 9, .NET Core code is in the following repository.