的Int32＆gt;在二元运算符平等是不是可空类型℃之间定义;和的Int32 [英] The binary operator Equal is not defined between type Nullable<Int32> and Int32

问题描述

我有以下型号：

public class DeviceConfigurationModel
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    [Display(Name = "Device Configuration Id")]
    public int DeviceConfigurationId { get; set; }

    [Required]
    [Display(Name = "Device Profile Name")]
    [StringLength(50)]
    public string ProfileName { get; set; }

    [StringLength(50)]
    public string SERV { get; set; }

    [StringLength(50)]
    public string IPAD { get; set; }

    public Nullable<int> PORT { get; set; }

    [Required]
    [Display(Name = "Is Active")]
    public bool IsActive { get; set; }

    [Required]
    [Display(Name = "Date Created")]
    public DateTime DateCreated { get; set; }
}

这是我通过包管理器控制台命令更新数据库，并在configuration.cs为迁移以下code种子：

which I seed through the package manager console with the command update-database and the following code in the configuration.cs for the migration:

    context.DeviceConfigurations.AddOrUpdate(
         d => new { d.ProfileName, d.IPAD, d.PORT, d.IsActive },
              new DeviceConfigurationModel { ProfileName = "FMG Default Gateway", IPAD = "77.86.28.50", PORT = (int?)90, IsActive = true  }
    );

然而，当它试图运行此行code的我在控制台中出现以下错误：

However, whenever it tries to run this line of code I get the following error in the console:

The binary operator Equal is not defined for the types 'System.Nullable`1[System.Int32]' and 'System.Int32'.

没有人知道如何解决这个问题，我试图寻找答案，但大多数解决方案都使其成为非空的，只是接受零，但是我不想这样做，因为我需要使用对于某些字段零值

does anyone know how to fix this problem, I have tried looking for answers but most of the solutions are to make it non-nullable and just accept a zero but I don't want to do this as I need to use a zero value for some of the fields

更新

打过这个进一步，我已经缩小下来事物的更新上运行列表：如果我在 d.PORT 从线漏下

Having played with this further, I have narrowed this down to the list of things the update is run on: if I leave out the d.PORT from the line

d => new { d.ProfileName, d.IPAD, d.PORT, d.IsActive }

则更新工作正常。当然，必须有一个方法，使更新还看这个领域，否则似乎使用MVC是pretty无用的，如果它甚至不能处理像一个可空INT一件简单的事情。

then the update works fine. Surely there must be a way to make the update also look at this field otherwise it seems that using mvc is pretty useless if it can't even handle a simple thing like a nullable int

推荐答案

尝试将字段设置为可选的明确使用流利的API：

Try setting the field to Optional explicitly using the Fluent API:

 public class YourContext : DbContext
    {
        public DbSet<DeviceConfigurationModel> DeviceConfigurations { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
            modelBuilder.Entity<DeviceConfigurationModel>().Property(x => x.PORT).IsOptional();
        }
    }

这应该强制类型为空。

由于某些原因，宣告你的财产为 INT 而不是可空＆LT; INT＆GT; 将导致EF产生你的财产如预期好。

For some reason, declaring your property as int? instead of Nullable<int> will cause EF to generate your property as expected as well.

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