server/src/Admin/Models/ChargeBraintreeModel.cs

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace Bit.Admin.Models
{
    public class ChargeBraintreeModel : IValidatableObject
    {
        [Required]
        [Display(Name = "Braintree Customer Id")]
        public string Id { get; set; }
        [Required]
        [Display(Name = "Amount")]
        public decimal? Amount { get; set; }
        public string TransactionId { get; set; }
        public string PayPalTransactionId { get; set; }

        public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
        {
            if (Id != null)
            {
                if (Id.Length != 36 || (Id[0] != 'o' && Id[0] != 'u') ||
                    !Guid.TryParse(Id.Substring(1, 32), out var guid))
                {
                    yield return new ValidationResult("Customer Id is not a valid format.");
                }
            }
        }
    }
}