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Validation

Overview​

ASOL.Core.Validation provides reusable validation helpers focused on phone number validation. The package exposes validation attributes for model properties and extension methods for custom validation implemented through IValidatableObject.

Install​

  • ASOL.Core.Validation

Usage third party libraries (NuGets)​

Usage​

The recommended entry point is PhoneNumberStrictAttribute. It uses libphonenumber-csharp and validates international phone numbers in a stricter way than the older PhoneNumberAttribute.

using ASOL.Core.Validation;
using System.ComponentModel.DataAnnotations;

public class ContactDto
{
    [PhoneNumberStrict]
    public string? PhoneNumber { get; set; }
}

null and empty string are treated as valid values. The validator expects an international format with country prefix, for example:

  • +420606123123
  • +420 606 123 123
  • +421907149209
  • +421 907 149 209

Examples that are rejected:

  • 606123123
  • 606 123 123
  • 00420 606 123 123
  • +420

If you implement custom validation through IValidatableObject, use the extension method ValidatePhoneNumberStrict.

using ASOL.Core.Validation;
using System.ComponentModel.DataAnnotations;

public class ContactDto : IValidatableObject
{
    public string? PhoneNumber { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        return this.ValidatePhoneNumberStrict(PhoneNumber);
    }
}

Error messages​

By default, the package returns a localized message from embedded resources:

  • Neplatné telefonní číslo.

You can override the message directly:

[PhoneNumberStrict("Invalid contact phone number.")]
public string? PhoneNumber { get; set; }

PhoneNumberAttribute and ValidatePhoneNumber(...) are still available for backward compatibility, but both are marked as obsolete. Prefer the strict variants for new code.