c# - 如何将 DbContext 与 FluentValidator 一起使用
问题描述
当我尝试编辑用户时出现以下错误。创建或删除用户没有问题。据我了解, fluentvalidator 类中的 uniqueMail 方法和 UserController 类中的 Edit 方法不能很好地结合在一起。
抛出异常:
_context.Update(user)
我认为问题是由于 fluentvalidator 类中的 dbcontext 使用不正确造成的。我想说在 fluentvalidator 类中处理上下文有些问题。
你能帮我理解什么是错的吗?
我还添加了 StartUp 类,以防 FluentValidation 的实现出现问题
错误:
System.InvalidOperationException:无法跟踪实体类型“用户”的实例,因为已经在跟踪具有相同键值的 {'Id'} 的另一个实例。附加现有实体时,请确保仅附加一个具有给定键值的实体实例。考虑使用“DbContextOptionsBuilder.EnableSensitiveDataLogging”来查看冲突的键值。
FluentValidator 类:
using FluentValidation;
using System.Linq;
namespace UserDirectory.Models
{
public class UserValidator : AbstractValidator<User>
{
readonly MvcUserContext _context;
public UserValidator(MvcUserContext context)
{
_context = context;
RuleFor(x => x.Email).Must(uniqueMail).WithMessage("This email is already in use");
RuleFor(x => x.Phone).Must(uniquePhone).WithMessage("This phone is already in use");
}
private bool uniqueMail(User user, string email)
{
var mail = _context.User.Where(x => x.Email.ToLower() == user.Email.ToLower()).SingleOrDefault();
if (mail == null) return true;
return mail.Id == user.Id;
}
private bool uniquePhone(User user, string phone)
{
var phoneNumber = _context.User.Where(x => x.Phone == user.Phone).SingleOrDefault();
if (phoneNumber == null) return true;
return phoneNumber.Id == user.Id;
}
}
}
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.AspNetCore.Mvc.Rendering;
using Microsoft.EntityFrameworkCore;
using UserDirectory.Models;
namespace UserDirectory.Controllers
{
public class UsersController : Controller
{
private readonly MvcUserContext _context;
public UsersController(MvcUserContext context)
{
_context = context;
}
// GET: Users
public async Task<IActionResult> Index(string sortOrder)
{
ViewData["NameSortParm"] = String.IsNullOrEmpty(sortOrder) ? "name_desc" : "";
ViewData["SurnameSortParm"] = String.IsNullOrEmpty(sortOrder) ? "surname_desc" : "";
var users = from u in _context.User
select u;
switch (sortOrder)
{
case "surname_desc":
users = users.OrderByDescending(u => u.Surname);
break;
case "name_desc":
users = users.OrderByDescending(u => u.Name);
break;
}
return View(await users.AsNoTracking().ToListAsync());
}
// GET: Users/Details/5
public async Task<IActionResult> Details(int? id)
{
if (id == null)
{
return NotFound();
}
var user = await _context.User
.FirstOrDefaultAsync(m => m.Id == id);
if (user == null)
{
return NotFound();
}
return View(user);
}
// GET: Users/Create
public IActionResult Create()
{
return View();
}
// POST: Users/Create
// To protect from overposting attacks, enable the specific properties you want to bind to.
// For more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create([Bind("Id,Name,Surname,Email,BirthDate,Phone,Location")] User user)
{
if (ModelState.IsValid)
{
_context.Add(user);
await _context.SaveChangesAsync();
return RedirectToAction(nameof(Index));
}
return View(user);
}
// GET: Users/Edit/5
public async Task<IActionResult> Edit(int? id)
{
if (id == null)
{
return NotFound();
}
var user = await _context.User.FindAsync(id);
if (user == null)
{
return NotFound();
}
return View(user);
}
// POST: Users/Edit/5
// To protect from overposting attacks, enable the specific properties you want to bind to.
// For more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Edit(int id, [Bind("Id,Name,Surname,Email,BirthDate,Phone,Location")] User user)
{
if (id != user.Id)
{
return NotFound();
}
if (ModelState.IsValid)
{
try
{
_context.Update(user);
await _context.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException)
{
if (!UserExists(user.Id))
{
return NotFound();
}
else
{
throw;
}
}
return RedirectToAction(nameof(Index));
}
return View(user);
}
// GET: Users/Delete/5
public async Task<IActionResult> Delete(int? id)
{
if (id == null)
{
return NotFound();
}
var user = await _context.User
.FirstOrDefaultAsync(m => m.Id == id);
if (user == null)
{
return NotFound();
}
return View(user);
}
// POST: Users/Delete/5
[HttpPost, ActionName("Delete")]
[ValidateAntiForgeryToken]
public async Task<IActionResult> DeleteConfirmed(int id)
{
var user = await _context.User.FindAsync(id);
_context.User.Remove(user);
await _context.SaveChangesAsync();
return RedirectToAction(nameof(Index));
}
private bool UserExists(int id)
{
return _context.User.Any(e => e.Id == id);
}
}
}
启动.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.EntityFrameworkCore;
using FluentValidation.AspNetCore;
using UserDirectory.Models;
namespace UserDirectory
{
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddControllersWithViews();
services.AddMvc().AddFluentValidation(fv => fv.RegisterValidatorsFromAssemblyContaining<Models.UserValidator>());
//services.AddTransient<FluentValidation.IValidator<User>, UserValidator>();
services.AddDbContext<MvcUserContext>(options =>
options.UseSqlite(Configuration.GetConnectionString("MvcUserContext")));
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Home/Error");
// The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllerRoute(
name: "default",
pattern: "{controller=Home}/{action=Index}/{id?}");
});
}
}
}
解决方案
在验证器上,您从用户中选择并跟踪您将更新的同一实体,这会导致问题。
代替
var mail = _context.User.Where(x => x.Email.ToLower() == user.Email.ToLower()).SingleOrDefault();
写
// The AsNoTracking do not add to the context the entity you select
var mail = _context.User.AsNoTracking().Where(x => x.Email.ToLower() == user.Email.ToLower()).SingleOrDefault();
使用该Where
子句,您可以实现整个实体用户(添加 AsNoTracking 不会将其添加到上下文中),但是如果您只想检查实体是否存在,您可以使用Any
转换为这样的 SQL 的子句
SELECT TOP 1
FROM TABLE
WHERE Email = 'myEmail'
结果不是用户实体,因此不会添加到上下文中。
return _context.User.Any(x => x.Email.ToLower() == user.Email.ToLower());
这是必须为uniqueMail
和uniquePhone
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