Get Error : Entity type 'Course' is defined with a single key property, but 2 values were passed to the 'DbSet.Find' method

Question

我有一个 GenericRepository，CourseRepository 继承自它，而 Entities returns 一个课程列表

 public class CourseRepository : GenericRepositories<Course>, ICourseRepository
        {
            public CourseRepository(LearningSiteDbContext Context) : base(Context)
            {

            }
         }

 public class GenericRepositories<TEntity> : IGenericRepositories<TEntity> where TEntity : class, IEntity,new()
    {
        protected readonly LearningSiteDbContext context;
        public DbSet<TEntity> Entities { get; set; }

        public GenericRepositories(LearningSiteDbContext Context)
        {
            context = Context;
            Entities = context.Set<TEntity>();
        }
    }

但是当我 运行 这个处理程序在 Razor 页面中时

 public async Task OnGetAsync(int Id, CancellationToken cancellationToken)
 {
    var selectedCourse = await courseRepository.Entities.FindAsync(Id,cancellationToken);
                Model = mapper.Map<CourseEditVm>(selectedCourse);
  }

我收到以下错误：

实体类型 'Course' 是用单个键 属性 定义的，但是 2 个值被传递给 'DbSet.Find' 方法

这是课程实体class

public class Course 
{
    public Course()
    {

    }
    public Course(DateTime CreateDate)
    {
        this.CreateDate = CreateDate;
    }

    public int Id {get;set;}

    public string CourseTitle { get; set; }

    public string CourseDescription { get; set; }

    public decimal CoursePrice { get; set; }

    public string ImageName { get; set; }

    public string DemoFileName { get; set; }

    public DateTime CreateDate { get; set; }

    public DateTime? UpdateDate { get; set; }
    public bool IsDeleted { get; set; }

    //Foreign key
    public int? CourseStatusId { get; set; }
    public int? CourseLevelId { get; set; }
    public Guid? CustomUserId { get; set; }
    public int? CourseGroupId { get; set; }

    //Navigations
    public CourseStatus CourseStatus { get; set; }
    public CourseLevel CourseLevel { get; set; }
    public CustomUser CustomUser { get; set; }
    public CourseGroup CourseGroup { get; set; }
    public ICollection<CourseEpisod> CourseEpisods { get; set; }
    public ICollection<Keyword> Keywordkeys { get; set; }
}

这是课程配置

class CourseConfig : IEntityTypeConfiguration<Course>
{
    public void Configure(EntityTypeBuilder<Course> builder)
    {
        builder.HasKey(c => c.Id);
        builder.Property(c => c.Id).ValueGeneratedOnAdd();
        builder.Property(c => c.CourseTitle).HasMaxLength(50);
        builder.Property(c => c.CourseDescription).HasMaxLength(400);
        builder.Property(c => c.ImageName).HasMaxLength(255);
        builder.Property(c => c.DemoFileName).HasMaxLength(255);

        //Relations
        builder.HasMany(c => c.Keywordkeys).WithOne(c => c.Course).HasForeignKey(c => c.CourseId);
        builder.HasOne(c => c.CustomUser).WithMany(c => c.Courses).HasForeignKey(c => c.CustomUserId);
    }
}

但是当我运行这段代码时，我将不再收到这个错误

  var selectedCourse = await courseRepository.Entities.FirstOrDefaultAsync(c => c.Id == Id, cancellationToken);

这个错误的原因是什么？我的代码错了吗？我该如何解决这个错误？

Answer 1

你用错方法了，如果你在这里查看 FindAsync 你可以看到，如果你想传递一个取消令牌，你需要像这样将你的密钥作为数组传递

.FindAsync(new object[]{id}, cancellationToken);