试图构建一个视图，我得到了“；无法检索“”的元数据；和'；验证错误''；实体类型没有定义键'；

本文关键字：元数据 验证 定义 类型 错误 实体 检索 构建 一个 视图 | 更新日期: 2023-09-27 17:53:43

我有一个程序，我试图找出我的朋友们没有得到的问题。我正试图从我的控制器中构建一个视图，我得到了一个

error "Unable to retrieve metadata for 'GradedWork.Controllers.CourseAddForm'. 
One or more validation errors were detected during model generation: 
GradedWork.Model.CourseAddForm : EntityType 'CourseAddForm' has no key defined. Define the 
key for this EntityType. CourseAddForm: EntityType: EntitySet 'CourseAddForm' is based on 
type 'CourseAddForm' that has no keys defined.'

我试图使用CourseAddForm视图模型类构建一个创建视图，但我总是遇到这个错误。

我的CourseAddForm课程不应该包含关键字段，我的朋友们没有我遇到的这个问题。

我的视图模型类：

namespace GradedWork.Controllers
{
public class CourseList
{
    [Key]
    public int Id { get; set; }
    [Display(Name = "Name")]
    public string Name { get; set; }
}
public class CourseAddForm
{

    [Display(Name = "Course Code")]
    public int CourseCode { get; set; }
    // [Required]
    [Display(Name = "Name")]
    public string Name { get; set; }
    //  [Required]
    [Display(Name = "Semester")]
    public string Semester { get; set; }
    // [Required]
    [Display(Name = "Section Id")]
    public string SectionId { get; set; }
    [Display(Name = "Teacher")]
    public ICollection<TeacherList> Teacher { get; set; }
    [Display(Name = "Student")]
    public ICollection<StudentList> Students { get; set; }
    [Display(Name = "Graded Works")]
    public ICollection<GradedWorkList> GradedWorks { get; set; }

    public CourseAddForm()
    {
        this.Teacher = new List<TeacherList>();
        this.Students = new List<StudentList>();
        this.GradedWorks = new List<GradedWorkList>();
    }
}
public class CourseAdd
{
    [Display(Name = "Course Code")]
    public int CourseCode { get; set; }
    // [Required]
    [Display(Name = "Name")]
    public string Name { get; set; }
    //  [Required]
    [Display(Name = "Semester")]
    public string Semester { get; set; }
    // [Required]
    [Display(Name = "Section Id")]
    public string SectionId { get; set; }
    [Display(Name = "Teacher")]
    public ICollection<Teacher> Teacher { get; set; }
    [Display(Name = "Student")]
    public ICollection<Student> Students { get; set; }
    [Display(Name = "Graded Works")]
    public ICollection<GradedWorks> GradedWorks { get; set; }

    public CourseAdd()
    {
        this.Teacher = new List<Teacher>();
        this.Students = new List<Student>();
        this.GradedWorks = new List<GradedWorks>();
    }
}
public class CourseBase : CourseAdd
{
    [Key]
    public int Id { get; set; }
}
}

我的控制器方法，我正试图脚手架

public ActionResult Create()
    {
        var addForm = new CourseAddForm();
        foreach (var item in m.GetAllTeachersAsList())
        {
            addForm.Teacher.Add(item);
        }
        foreach (var item in m.GetAllStudentsAsList())
        {
            addForm.Students.Add(item);
        }
        foreach (var item in m.GetAllGradedWorkAsList())
        {
            addForm.GradedWorks.Add(item);
        }
        return View(addForm);
    }
    //
    // POST: /Course/Create
    [HttpPost]
    public ActionResult Create(CourseAdd newItem)
    {
        if (ModelState.IsValid)
        {
            var addedItem = m.AddCourse(newItem);
            if (addedItem == null)
            {
                return RedirectToAction("Index");
            }
            else
            {
                return RedirectToAction("Details", new { id = addedItem.Id });
            }

        }
        else
        {
            var addForm = Mapper.Map<CourseAddForm>(newItem);
            foreach (var item in m.GetAllTeachersAsList())
            {
                addForm.Teacher.Add(item);
            }
            foreach (var item in m.GetAllStudentsAsList())
            {
                addForm.Students.Add(item);
            }
            foreach (var item in m.GetAllGradedWorkAsList())
            {
                addForm.GradedWorks.Add(item);
            }
            return View(addForm);
        }
    }

我的连接字符串：

<connectionStrings>
<add name="DataContext" connectionString="Data Source=(LocalDb)'v11.0;AttachDbFilename=|DataDirectory|'StoreName.mdf;Initial Catalog=StoreName;Integrated Security=True" providerName="System.Data.SqlClient" />

试图构建一个视图，我得到了“；无法检索“”的元数据；和'；验证错误''；实体类型没有定义键'；

我所要做的就是删除脚手架中的datacontext选项，它就可以工作了。。。

我想知道您的继承方向是否错误。您在CourseBase上有一个主键，但CourseBase在承载CourseAdd。因此，CourseAdd的所有性质都是CourseBase的一部分，而不是相反。因此，CourseAdd上没有主键，正如神秘的错误消息试图说的那样，"没有定义主键"。

尝试：

public class CourseAdd : CourseBase {
    // trim
}

并使CCD_ 7不继承CCD_。

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