如何验证电子邮件属性在 ASP .NET CORE API 中是否唯一？

Question

我需要发帖或在服务器端进行验证以检查电子邮件是否唯一。

在研究中，我一直做的例子是一个传统的 MVC 应用程序，而不是一个 api。

在许多情况下，我看到 [Remote] https://docs.microsoft.com/pt-br/aspnet/core/mvc/models/validation?view=aspnetcore-2.2#remote-attribute。我尝试按照文档来实现，但是调试验证了控制器中的函数没有被调用。

用户.cs

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.AspNetCore.Mvc;

namespace Base.Models
{
    [Table("users")]
    public partial class User
    {
        ...
        [Required]
        [EmailAddress]
        [Remote(action: "VerifyEmail", controller: "UserController",ErrorMessage="Email already in use")]
        [Column("email", TypeName = "varchar(254)")]
        public string Email { get; set; }
        ...
    }
}

用户控制器.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Base.Models;

namespace Base.Controllers
{
    [Route("api/users")]
    [ApiController]
    public class UserController : Controller
    {
        ...
        [AcceptVerbs("Get")]
        public IActionResult VerifyEmail(string email)
        {
            //forcing it to go wrong
            return Json($"Email {email} is already in use.");
        }
        ...
    }
}

任何人都知道如何实现这一点？

Answer 1

看到它没有进展，我决定进行个性化验证。

电子邮件用户唯一属性.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel.DataAnnotations;
using Base.Models;

namespace Core.Models
{
    public class EmailUserUniqueAttribute : ValidationAttribute
    {
        protected override ValidationResult IsValid(
            object value, ValidationContext validationContext)
        {
            var _context = (AppDbContext)validationContext.GetService(typeof(AppDbContext));
            var entity = _context.Users.SingleOrDefault(e => e.Email == value.ToString());

            if (entity != null)
            {
                return new ValidationResult(GetErrorMessage(value.ToString()));
            }
            return ValidationResult.Success;
        }

        public string GetErrorMessage(string email)
        {
            return $"Email {email} is already in use.";
        }
    }
}

用户.cs

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.AspNetCore.Mvc;

namespace Base.Models
{
    [Table("users")]
    public partial class User
    {
        ...
        [Required]
        [EmailAddress]
        [EmailUserUnique]
        [Column("email", TypeName = "varchar(254)")]
        public string Email { get; set; }
    }
}
        ...

它有效，但我不知道这是否是最好的方法。