'；对象引用未设置为对象的实例'；来自匿名数组的错误

本文关键字：数组 错误 对象 对象引用 设置 实例 | 更新日期: 2023-09-27 18:30:14

InquiryOrder模型

public class InquiryOrder
{
    [Key]
    public int InquiryOrderId { get; set; }
    public string InquiryOrderName { get; set; }
    [ForeignKey("ProductType")]
    public int? ProductTypeId { get; set; }
    public virtual ProductType ProductType { get; set; }
}

产品类型型号

public class ProductType
{
    [Key]
    public int ProductId { get; set; }
    [StringLength(100, ErrorMessage = "Must be less than 100 charcters", MinimumLength = 1)]
    [Required(ErrorMessage = "Required")]
    public string ProductTypeName { get; set; }
    public virtual List<InquiryOrder> inquiryOrders { get; set; }
}

查询订单控制器

var displayedInquiryOrders = filteredInquiryOrders.Skip(iDisplayStart).Take(iDisplayLength);
        var result = from c in displayedInquiryOrders .AsEnumerable()
                      select new[] { 
                                Convert.ToString(c.InquiryOrderId),
                                c.InquiryOrderName,
                                c.ProductType.ProductTypeName,
                            };

这里从c.ProductType.ProductTypeName，我得到这个错误Object reference not set to an instance of an object。请帮我解决这个问题。谢谢

'；对象引用未设置为对象的实例'；来自匿名数组的错误

此处为

new[] { 
                            Convert.ToString(c.InquiryOrderId),
                            c.InquiryOrderName,
                            c.ProductType.ProductTypeName,
                        };

任一：

  • c为空
  • c.ProductType为空

您需要添加一些NullReference控件。请试试这个：

           select new[]{ 
                            Convert.ToString(c?.InquiryOrderId),
                            c?.InquiryOrderName,
                            c?.ProductType?.ProductTypeName,
                        };
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