.NET CORE2.0 内置Identity 迁移至Mysql主键过长的解决方案

使用EntityFrameworkMysql+NETCORE2.0内置Identity时，会报错主键过长导致三张核心表无法创建，在ApplicationDbContext中重写OnModelCreating即可

public class ApplicationDbContext : IdentityDbContext<ApplicationUser, ApplicationRole, int>
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options)
    {

    }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);
        //和设置的表主键对应
        builder.Entity<IdentityUserLogin<int>>(e => e.Property(p => p.LoginProvider).HasMaxLength(128));
        builder.Entity<IdentityUserLogin<int>>(e => e.Property(p => p.ProviderKey).HasMaxLength(128));

        builder.Entity<IdentityUserToken<int>>(e => e.Property(p => p.LoginProvider).HasMaxLength(128));
        builder.Entity<IdentityUserToken<int>>(e => e.Property(p => p.Name).HasMaxLength(128));
    }

}

重新执行迁移数据库代码，可以正常生成了！