扩展Asp.Net Core中的IdentityUser类

　　虽然Asp.Net Core.Identity提供了IdentityUser类，但是在有些情况下我们需要一些额外的用户信息，比如性别，年龄等，这时候就需要来扩展IdentityUser类以达到我们的需求。

namespace Microsoft.AspNetCore.Identity
{
    //
    // 摘要:
    //     Represents a user in the identity system
    //
    // 类型参数:
    //   TKey:
    //     The type used for the primary key for the user.
    public class IdentityUser<TKey> where TKey : IEquatable<TKey>
    {
        //
        // 摘要:
        //     Initializes a new instance of Microsoft.AspNetCore.Identity.IdentityUser`1.
        public IdentityUser();
        //
        // 摘要:
        //     Initializes a new instance of Microsoft.AspNetCore.Identity.IdentityUser`1.
        //
        // 参数:
        //   userName:
        //     The user name.
        public IdentityUser(string userName);

        //
        // 摘要:
        //     Gets or sets the date and time, in UTC, when any user lockout ends.
        //
        // 言论：
        //     A value in the past means the user is not locked out.
        public virtual DateTimeOffset? LockoutEnd { get; set; }
        //
        // 摘要:
        //     Gets or sets a flag indicating if two factor authentication is enabled for this
        //     user.
        [PersonalData]
        public virtual bool TwoFactorEnabled { get; set; }
        //
        // 摘要:
        //     Gets or sets a flag indicating if a user has confirmed their telephone address.
        [PersonalData]
        public virtual bool PhoneNumberConfirmed { get; set; }
        //
        // 摘要:
        //     Gets or sets a telephone number for the user.
        [ProtectedPersonalData]
        public virtual string PhoneNumber { get; set; }
        //
        // 摘要:
        //     A random value that must change whenever a user is persisted to the store
        public virtual string ConcurrencyStamp { get; set; }
        //
        // 摘要:
        //     A random value that must change whenever a users credentials change (password
        //     changed, login removed)
        public virtual string SecurityStamp { get; set; }
        //
        // 摘要:
        //     Gets or sets a salted and hashed representation of the password for this user.
        public virtual string PasswordHash { get; set; }
        //
        // 摘要:
        //     Gets or sets a flag indicating if a user has confirmed their email address.
        [PersonalData]
        public virtual bool EmailConfirmed { get; set; }
        //
        // 摘要:
        //     Gets or sets the normalized email address for this user.
        public virtual string NormalizedEmail { get; set; }
        //
        // 摘要:
        //     Gets or sets the email address for this user.
        [ProtectedPersonalData]
        public virtual string Email { get; set; }
        //
        // 摘要:
        //     Gets or sets the normalized user name for this user.
        public virtual string NormalizedUserName { get; set; }
        //
        // 摘要:
        //     Gets or sets the user name for this user.
        [ProtectedPersonalData]
        public virtual string UserName { get; set; }
        //
        // 摘要:
        //     Gets or sets the primary key for this user.
        [PersonalData]
        public virtual TKey Id { get; set; }
        //
        // 摘要:
        //     Gets or sets a flag indicating if the user could be locked out.
        public virtual bool LockoutEnabled { get; set; }
        //
        // 摘要:
        //     Gets or sets the number of failed login attempts for the current user.
        public virtual int AccessFailedCount { get; set; }

        //
        // 摘要:
        //     Returns the username for this user.
        public override string ToString();
    }
}

　　接下来我们就来定义一个继承自IdentityUser类的ApplicationUser类。

public class ApplicationUser : IdentityUser
{
    public string City { get; set; }
}

　　然后在AppDbContext中继承泛型 IdentityDbContext<ApplicationUser>类。并且在Startup中注入的时候把IdentityUser修改为ApplicationUser后，再做数据库迁移，如果之前已经迁移过，则需要替换项目中所有的IdentityUser为ApplicationUser。

public class AppDbContext:IdentityDbContext<ApplicationUser>
{

    public AppDbContext(DbContextOptions<AppDbContext> options):base(options)
    {
    }

    public DbSet<Student> Students { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        modelBuilder.Seed();
    }
}

services.AddIdentity<ApplicationUser, IdentityRole>()
    .AddErrorDescriber<CustomIdentityErrorDescriber>()
    .AddEntityFrameworkStores<AppDbContext>();