UserManager.FindByEmailAsync 返回 null，但用户存在于数据库中

Question

UserManager.FindByEmailAsync返回null，但该用户存在于数据库中。

下面的代码解释了这个奇怪的问题：

var email = info.Principal.FindFirstValue(ClaimTypes.Email);
var test = new Data.ApplicationDbContext().Users.First(x => x.NormalizedEmail == email);
var usermail = await _userManager.FindByEmailAsync(email);

Console.WriteLine(test == null);      //false
Console.WriteLine(usermail == null);  //true

编辑

同样通过_userManager其自身，可以获得所需的用户：

var test = _userManager.Users.FirstOrDefault(x => x.NormalizedEmail == email);
var usermail = await _userManager.FindByEmailAsync(email);

Console.WriteLine(test == null);      //false
Console.WriteLine(usermail == null);  //true

需要注意的是，用户不是以“常规”方式创建的，而是通过 Data-Seed 创建的（在OnModelCreating）：

protected override void OnModelCreating(ModelBuilder builder)
{
    var users = new (string email, string name)[] {
        ("xyz@gmail.com", "admin")
    };

    var appUsers = users.Select(x => new ApplicationUser
    {
        Email = x.email,
        NormalizedEmail = x.email,
        NormalizedUserName = x.email,
        UserName = x.email,
        EmailConfirmed = true,
        Id = Guid.NewGuid().ToString(),
        SecurityStamp = Guid.NewGuid().ToString()
    }).ToArray();

    var role = new IdentityRole("Admins") { Id = Guid.NewGuid().ToString() };
    var roleToUser = appUsers.Select(x => new IdentityUserRole<string> { RoleId = role.Id, UserId = x.Id });

    builder.Entity<ApplicationUser>().HasData(appUsers);
    builder.Entity<IdentityRole>().HasData(role);
    builder.Entity<IdentityUserRole<string>>().HasData(roleToUser);
        
    base.OnModelCreating(builder);
}

Answer 1

正如您在我对您的 OP 所做的评论中的源代码链接中看到的那样， FindByEmailAsync在实际开始搜索用户之前执行NormalizeKey 。

email = NormalizeKey(email);

这NormalizeKey(email)是由UpperInvariantLookupNormalizer完成的，它将对您的电子邮件执行以下字符串操作

return key.Normalize().ToUpperInvariant();

现在，导致“奇怪”行为的代码部分是在创建用户时缺少对代码中规范化的调用：

var appUsers = users.Select(x => new ApplicationUser
{
    Email = x.email,
    NormalizedEmail = x.email,
    NormalizedUserName = x.email,
    UserName = x.email,
    EmailConfirmed = true,
    Id = Guid.NewGuid().ToString(),
    SecurityStamp = Guid.NewGuid().ToString()
}).ToArray();

不规范化电子邮件仍将使其可通过用户表发现，因为这只是将NormalizedEmail（创建用户时未规范化的）与作为参数传递的非规范化电子邮件进行比较：

_userManager.Users.FirstOrDefault(x => x.NormalizedEmail == email);

...但是，首先userManager.FindByEmailAsync将其标准化，然后进行搜索...

_userManager.FindByEmailAsync(email);

...因此找不到用户。

将您的代码更改为以下内容：

// inject via using Microsoft.AspNetCore.Identity
protected ILookupNormalizer normalizer;

var appUsers = users.Select(x => new ApplicationUser
{
    Email = x.email,
    NormalizedEmail = normalizer.Normalize(x.email),
    NormalizedUserName = normalizer.Normalize(x.email),
    UserName = x.email,
    EmailConfirmed = true,
    Id = Guid.NewGuid().ToString(),
    SecurityStamp = Guid.NewGuid().ToString()
}).ToArray();