我正在学习Webapi，所以我试图建立一个简单的API连接到SQL服务器，我得到了这个错误，当我添加新的电影数据
Microsoft.EntityFrameworkCore.DbUpdateException:保存实体更改时出错。有关详细信息，请参见内部异常。-> Microsoft.Data.SqlClient.SqlException（0x80131904）：INSERT语句与FOREIGN KEY约束“FK_Movies_SuperHeroes_HeroId”冲突。数据库“SupersDb”，表“dbo.SuperHeroes”，列“HeroId”发生冲突。
我有两个模型：
超级英雄模型：

namespace SuperHeroesApi.Models
{
    public class SuperHero
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int HeroId { get; set; }

        [Required]
        [MaxLength(100)]
        public string Name { get; set; } 

       
        [MaxLength(100)]
        public string FirstName { get; set; } 

        [MaxLength(100)]
        public string LastName { get; set; }

        [MaxLength(100)]
        public string City { get; set; } 







    }
}

字符串
影片型号：

namespace SuperHeroesApi.Models
{
    public class Movie
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int MovieId { get; set; }

        [Required]
        [MaxLength(100)]
        public string Title { get; set; }

        public int Year { get; set; }

        public double Rate { get; set; }

        public byte [] Poster { get; set; }

        [ForeignKey("SuperHero")]
        public int HeroId { get; set; }
       

        //public string  SuuperHeroName { get; set; }

        public virtual SuperHero SuperHero { get; set; }



    }
}

型
dto：

namespace SuperHeroesApi.Otds
{
    public class MoviesDtos
    {

        public string Title { get; set; }

        public int Year { get; set; }

        public double Rate { get; set; }

        public IFormFile Poster { get; set; }

        [ForeignKey("SuperHero")]
        public int HeroId { get; set; }


    }
}

型
MoviesController：

using SuperHeroesApi.Otds;

namespace SuperHeroesApi.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class MoviesController : ControllerBase
    {

        private readonly AppDbContext _dbContext;

        private new List<string> _allowedExtention = new List<string> { "jbg", "png" };
        private long _maxAllowedPosterSize = 5242880;

        public MoviesController(AppDbContext dbContext)
        {
            _dbContext = dbContext;
        }

        [HttpGet]
        public async Task<IActionResult>GetAllAsync()
        {
            var movie = await _dbContext.Movies.ToListAsync();

            return Ok(movie);

        }

        [HttpPost]
        public async Task <IActionResult> CreateAsync([FromForm] MoviesDtos dto)
        {
            if (_allowedExtention.Contains(Path.GetExtension(dto.Poster.FileName).ToLower()))
                return BadRequest();

            using var dataStream = new MemoryStream();
            await dto.Poster.CopyToAsync(dataStream);

            var movie = new Movie
            {
                Title = dto.Title,
                Year = dto.Year,
                Rate = dto.Rate,

                Poster = dataStream.ToArray(),
            };

              await _dbContext.AddAsync(movie);
              _dbContext.SaveChanges();

            return Ok(movie);
        }



    }
}

型