DataAnnotationsAttributes.cs

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *--------------------------------------------------------------------------------------------*/

namespace System.ComponentModel.DataAnnotations;

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
internal sealed class Base64StringAttribute : ValidationAttribute
{
    public override bool IsValid(object? value)
    {
        if (value is null)
        {
            return true;
        }

        if (value is not string text)
        {
            return false;
        }

        try
        {
            Convert.FromBase64String(text);
            return true;
        }
        catch (FormatException)
        {
            return false;
        }
    }
}