为什么 modelstate.isvalid 总是 false，尽管模型中的图片属性被分配了

Question

我正在开发一个剃刀页面项目。我有一个员工模型，它具有字节数组类型的图片属性。尽管当我检查

modelstate.isvalid

时，图片被分配了字节数组，但

emp.picture

无效，这里是我的员工模型和相关代码：

public class Employee
{
    public int Id { get; set; }

    [Required(ErrorMessage = "Please enter first name")]
    [DisplayName("First Name")]
    public string FirstName { get; set; }

    [Required(ErrorMessage = "Please enter last name")]
    [DisplayName("Last Name")]
    public string LastName { get; set; }


    [Required(ErrorMessage = "Please enter age")]
    [Range(20, 60, ErrorMessage = "Valid age is between 20 to 60")]
    public int Age { get; set; }

    [Required(ErrorMessage = "Please select joining date")]
    [DisplayName("Joining Date")]
    [DataType(DataType.Date)]
    public DateTime JoiningDate { get; set; }

    [Required(ErrorMessage = "Please enter email address")]
    [EmailAddress]
    public string Email { get; set; }

    [Required(ErrorMessage = "Please enter phone number")]
    [DisplayName ("Phone No")]
    [Phone]
  
    public string PhoneNo { get; set; }
    public byte[] Picture { get; set; }

    public bool Gender { get; set; }
    public bool Active { get; set; } = true;

    [Required(ErrorMessage = "Please select a Department")]
    public int DepartmentId { get; set; }
    public Department? Department { get; set; }

    [NotMapped]
    public IFormFile ImageFile { get; set; }
}

    public async Task<IActionResult> OnPostAsync()
    {
       byte[] bytes;
        if (emp.ImageFile != null)
        {
            using (Stream fs = emp.ImageFile.OpenReadStream())
            {
                using (BinaryReader br = new BinaryReader(fs))
                {
                    bytes = br.ReadBytes((Int32)fs.Length);

                }
            }
            emp.Picture = bytes;
        }
      
        if (!ModelState.IsValid)
        {
            return Page();
        }
       
        _db.Employees.Add(emp);
        await _db.SaveChangesAsync();
        TempData["Success"] = "Employee created successfully....";
        return RedirectToPage("/Employees/Index");
    }
}

我期望该图片应该具有价值，但我不知道为什么没有。

Answer 1

模型绑定发生在

OnPostAsync

方法中的代码执行之前，并且

ModelState

不会因您向

Picture

属性赋值而更新。 当您很高兴为

ModelState.Remove

分配了值后，可以使用

Picture

方法删除无效条目：

public async Task<IActionResult> OnPostAsync()
{
    byte[] bytes;
    if (emp.ImageFile != null)
    {
        using (Stream fs = emp.ImageFile.OpenReadStream())
        {
            using (BinaryReader br = new BinaryReader(fs))
            {
                bytes = br.ReadBytes((Int32)fs.Length);

            }
        }
        emp.Picture = bytes;
        ModelState.Remove("emp.Picture");
    }
      
    if (!ModelState.IsValid)
    {
        return Page();
    }
       
    _db.Employees.Add(emp);
    await _db.SaveChangesAsync();
    TempData["Success"] = "Employee created successfully....";
    return RedirectToPage("/Employees/Index");
}