MVC模型如何使byte []可为空? [英] MVC Model How to make byte[] nullable?

问题描述

我首先使用带有EF代码的ASP.NET MVC.

I'm using ASP.NET MVC with EF code first.

在我的模型中，我有一个可以为空的属性:

In my model I have a property that can be null:

    public byte[] Avatar { get; set; }

但是，当我运行更新数据库时，我得到:

However, when I run update-database I get:

无法将值NULL插入表'temp'的'Avatar'列中； 列不允许为空. UPDATE失败.

Cannot insert the value NULL into column 'Avatar', table 'temp'; column does not allow nulls. UPDATE fails.

我没有指定所需属性的数据注释，也不是外键.

I don't have a dataannotation specifying the property to be required, nor is the property a foreign key.

有什么想法吗?

进一步更新:

如果我删除数据库并使用'update-database -verbose'强制创建一个新数据库，则可以看到正在创建的表专门在字段上强制使用NOT NULL标志:

If I delete my database and force a new one to be created with 'update-database -verbose' then I can see the table being created specifically forces a NOT NULL flag on my field:

CREATE TABLE [dbo].[UserProfile] (
    [UserId] [int] NOT NULL IDENTITY,
    [UserName] [nvarchar](max),
    [FirstName] [nvarchar](50) NOT NULL,
    [LastName] [nvarchar](50) NOT NULL,
    [EmailAddress] [nvarchar](50) NOT NULL,
    [WorkPhone] [nvarchar](20),
    [MobilePhone] [nvarchar](20),
    [HireDate] [datetime],
    [Avatar] [image] NOT NULL,
    [AvatarMimeType] [nvarchar](max),
    CONSTRAINT [PK_dbo.UserProfile] PRIMARY KEY ([UserId])
)

我的完整模型:

    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int UserId { get; set; }
    public string UserName { get; set; }

    [Required]
    [Display(Name = "First name")]
    [MaxLength(50, ErrorMessage = "First Name cannot be longer than 50 characters.")]
    public string FirstName { get; set; }

    [Required]
    [Display(Name = "Last Name")]
    [MaxLength(50, ErrorMessage = "Last Name cannot be longer than 50 characters.")]
    public string LastName { get; set; }

    [Display(Name = "Full Name")]
    public string FullName
    {
        get
        {
            return FirstName + " " + LastName;
        }
    }

    [Required]
    [RegularExpression("^[a-z0-9_\\+-]+(\\.[a-z0-9_\\+-]+)*@[a-z0-9]+(\\.[a-z0-9]+)*\\.([a-z]{2,4})$", ErrorMessage = "Not a valid email address")]
    [Display(Name = "Email Address")]
    [MaxLength(50, ErrorMessage = "Email Address cannot be longer than 50 characters.")]
    public string EmailAddress { get; set; }

    [Display(Name = "Work Phone")]
    [MaxLength(20, ErrorMessage = "Work Phone cannot be longer than 20 characters.")]
    public string WorkPhone { get; set; }

    [Display(Name = "Mobile Phone")]
    [MaxLength(20, ErrorMessage = "Mobile Phone cannot be longer than 20 characters.")]
    public string MobilePhone { get; set; }

    [Display(Name = "Hire Date")]
    [DataType(DataType.Date), DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}", ApplyFormatInEditMode = true)]
    public DateTime? HireDate { get; set; }

    [ValidateFile(ErrorMessage = "Please select a PNG, JPG or GIF image smaller than 2MB")]
    [Column(TypeName = "image")]
    public byte[] Avatar { get; set; }

    public string AvatarMimeType { get; set; }

推荐答案

[Column(TypeName = "image")]
public byte[] Avatar { get; set; }

我认为您需要告诉EF您正在以这种方式使用它.尝试使用上述图像批注.

I think you need to tell EF that you are using it in this fashion. Try using the image annotation as above.

这将确保将您的字段创建为图像类型；为这种情况设计的.

This will make sure your field is created as the image type; designed for this type of scenario.

编辑:请查看注释以获取最终的答案.

Please see the comments for the answer that eventually worked.

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