EF Core执行数据种子迁移报IdentityUserLogin<string>需主键错误

• 重写OnModelCreating时没有调用基类IdentityDbContext.OnModelCreating()方法。Identity框架内置的IdentityUserLogin、IdentityUserRole等所有认证相关实体的主键、表映射规则都在基类方法里配置，直接覆盖方法逻辑不调用基类实现，会导致这些实体缺失主键配置，触发校验异常。
• 错误给Animal实体配置了HasNoKey()。无键实体类型仅用于只读查询、数据库视图映射场景，不支持增删改操作，也不支持HasData种子数据迁移，而Animal实体明确存在AnimalId字段作为业务主键，不需要配置无键。
• 种子数据里的日期字符串末尾多了多余逗号（比如"2022-08-01,"），就算解决前两个问题，运行时也会抛出日期格式解析错误。

• 修改AnimalShelterContext的OnModelCreating方法：
  1. 方法第一行先调用base.OnModelCreating(modelBuilder)，加载Identity框架的默认实体配置
  2. 移除Animal实体的HasNoKey()配置，显式指定AnimalId为主键（如果AnimalId字段已经加了[Key]数据标注，这步可省略）
  3. 删掉所有DateTime.Parse入参末尾多余的逗号
• 删除之前生成的错误迁移文件：如果之前生成过失败的迁移，直接删掉Migrations文件夹下对应批次的文件即可，全量重置可以直接删除整个Migrations文件夹
• 重新执行迁移生成命令：dotnet ef migrations add "data seed"
• 待迁移生成无报错后，执行dotnet ef database update将表结构和种子数据应用到数据库

using System;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

namespace AnimalShelter.Models
{
    public class AnimalShelterContext : IdentityDbContext
    {
        public AnimalShelterContext(DbContextOptions<AnimalShelterContext> options)
            : base(options)
        {   
        }
        public DbSet<Animal> Animals { get; set; }
    
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            // 必须首先调用基类方法完成Identity实体配置
            base.OnModelCreating(modelBuilder);

            modelBuilder.Entity<Animal>()
                .HasKey(a => a.AnimalId)
                .HasData(
                    new Animal { AnimalId = 6, Name = "Matilda", Neutered = "Y", Age = 7, Species = "Dog",  Gender = "Female", DateAdd = DateTime.Parse("2022-08-01")},
                    new Animal { AnimalId = 2, Name = "Rexie", Neutered = "Y", Age = 10, Species = "Dog",  Gender = "Female", DateAdd = DateTime.Parse("2022-02-01")},
                    new Animal { AnimalId = 3, Name = "Matilda", Neutered = "N", Age = 2, Species = "Cat",  Gender = "Female", DateAdd = DateTime.Parse("2022-03-01")},
                    new Animal { AnimalId = 4, Name = "Pip", Neutered = "Y", Age = 4, Species = "Bird",  Gender = "Male", DateAdd = DateTime.Parse("2022-07-01")},
                    new Animal { AnimalId = 5, Name = "Bartholomew", Neutered = "N", Age = 22, Species = "Cat",  Gender = "Male", DateAdd = DateTime.Parse("2022-06-01")}
                );
        }
    }
}

补充说明：只要继承了Identity相关的上下文类，重写OnModelCreating时都需要首先调用基类方法，否则Identity内置的所有实体配置都会丢失。

内容的提问来源于stack exchange，提问作者NWclimber