无法创建“AddressModel”类型的常量值。此上下文仅支持原始类型或枚举类型

Question

在下面的 EF 查询中，每当将子联系人地址字段分配给 TaxReceiptsWithChargesModel 的 Address 属性时，我都会收到错误消息：

“无法创建'AddressModel'类型的常量值”

如果我注释掉分配地址的行，则不会发生错误。可能是什么问题？

编辑：通常，我在其他地方看到的这个问题的原因与使用 contains 或 equals LINQ 方法有关，但这个特定问题的原因似乎在其他地方。

以下是相关的代码部分：

            //GetChildContactAddress
            var childContactAddress = lgcCcpModel.ChildContacts
                .Where(cc => cc.UUID == ltrm.ChildContactId)
                .Select(cc => new AddressModel()
                {
                    Address1 = cc.Address.STREET,
                    City = cc.Address.CITY,
                    Province = cc.Address.PROVINCE,
                    PostalCode = cc.Address.POSTALCODE
                }).FirstOrDefault();

        //Create the Tax Receipt Model with the Charge List
        return unitOfWork.LegacyTaxReceiptStore.GetQuery()
            .Where(ltr => ltr.LegacyTaxReceiptId ==         ltrm.LegacyTaxReceiptId)
            .Select(c => new TaxReceiptsWithChargesModel()
            {
                LegacyTaxReceiptId = ltrm.LegacyTaxReceiptId,
                ChildContactId = ltrm.ChildContactId,
                ChildContact = ltrm.ChildContact,
                EmailAddress = ltrm.EmailAddress,
                ChildId = ltrm.ChildId,
                ChildName = ltrm.ChildName,
                ChargesTotal = ltrm.ChargesTotal,
                TaxReceiptAmount = ltrm.TaxReceiptAmount.Value,
                TaxReceiptYear = ltrm.TaxReceiptYear,
                Address = childContactAddress,
                ReceiptNumber = $"{ltrm.TaxReceiptYear}-{ltrm.LegacyTaxReceiptId.ToString().PadLeft(6, '0')}",
                Charges = taxReceiptChargesModelList,
            }).FirstOrDefault();


public class TaxReceiptsWithChargesModel : ITaxReceiptsModel
    {
        public int LegacyTaxReceiptId { get; set; }
        public string ChildContactId { get; set; }
        public string ChildContact { get; set; }
        public string EmailAddress { get; set; }
        public IAddressModel Address { get; set; }
        public decimal? OpeningBalance { get; set; }
        public decimal? InvoicesTotal { get; set; }
        public decimal? PaymentsTotal { get; set; }
        public string ChildId { get; set; }
        public string ChildName { get; set; }
        public decimal? ChargesTotal { get; set; }
        public decimal? TaxReceiptAmount { get; set; }
        public string State { get; set; }
        public int TaxReceiptYear { get; set; }
        public string ReceiptNumber { get; set; }
        public int? BinaryDocumentId { get; set; }
        public List<TaxReceiptsChargesModel> Charges { get; set; }
    }

public interface IAddressModel
    {
        string Address1 { get; set; }
        string Address2 { get; set; }
        string City { get; set; }
        string Country { get; set; }
        string PostalCode { get; set; }
        string Province { get; set; }
    }

Answer 1

这是因为childContactAddress 对象（以及taxReceiptChargesModelList）已经在内存中，当您尝试在第二个查询的投影中分配一个复杂对象时，Linq 提供程序无法将该对象转换为 SQL。一种选择是调用AsEnumerable扩展方法：

  return unitOfWork.LegacyTaxReceiptStore.GetQuery()
        .Where(ltr => ltr.LegacyTaxReceiptId ==ltrm.LegacyTaxReceiptId)
        .AsEnumerable()
        .Select(c => new TaxReceiptsWithChargesModel()
        {
            LegacyTaxReceiptId = ltrm.LegacyTaxReceiptId,
            ChildContactId = ltrm.ChildContactId,
            ChildContact = ltrm.ChildContact,
            EmailAddress = ltrm.EmailAddress,
            ChildId = ltrm.ChildId,
            ChildName = ltrm.ChildName,
            ChargesTotal = ltrm.ChargesTotal,
            TaxReceiptAmount = ltrm.TaxReceiptAmount.Value,
            TaxReceiptYear = ltrm.TaxReceiptYear,
            Address = childContactAddress,
            ReceiptNumber = $"{ltrm.TaxReceiptYear}-{ltrm.LegacyTaxReceiptId.ToString().PadLeft(6, '0')}",
            Charges = taxReceiptChargesModelList, 
        }).FirstOrDefault();

更新

你的问题也可以这样解决：

var result=unitOfWork.LegacyTaxReceiptStore.GetQuery()
            .FirstOrDefault(ltr => ltr.LegacyTaxReceiptId ==ltrm.LegacyTaxReceiptId);

return new TaxReceiptsWithChargesModel()
        {
            LegacyTaxReceiptId = result.LegacyTaxReceiptId,
            ChildContactId = result.ChildContactId,
            ChildContact = result.ChildContact,
            EmailAddress = result.EmailAddress,
            ChildId = result.ChildId,
            ChildName = result.ChildName,
            ChargesTotal = result.ChargesTotal,
            TaxReceiptAmount = result.TaxReceiptAmount.Value,
            TaxReceiptYear = result.TaxReceiptYear,
            Address = childContactAddress,
            ReceiptNumber = $"{result.TaxReceiptYear}-{result.LegacyTaxReceiptId.ToString().PadLeft(6, '0')}",
            Charges = taxReceiptChargesModelList,
        };

Answer 2

您必须应用 [Serializable()] 装饰器，但不能对接口执行此操作。

相反，使用 ISerializable {}

实现您的自定义接口

下面已经回答了一个类似的问题，这篇文章的功劳归于 Oded。

Why are interfaces not [Serializable]?

干杯

Answer 3

你能告诉我使用接口作为模型属性有什么意义吗？ Microsoft 不鼓励将 in 接口用作模型属性。您可以使用 getter 和 setter 方法来限制您的属性的更改。 看到这个帖子 https://stackoverflow.com/a/8455558/2173098