为这个 Linq 查询抓狂。它是 Entity Framework 。查询确实转换为不同的模型对象。如果我评论或删除我指出导致错误的代码区域，则 linq 查询有效。但在我看来，我应该能够编写这样的查询而不会出现此错误:
无法创建“DomainModel.Model.CustomerAddress”类型的空常量值。在此上下文中仅支持实体类型、枚举类型或原始类型。
谁能告诉我为什么我不能或更重要的是我需要改变什么才能让它发挥作用？
谢谢
var orders = from o in _db.Orders
.Include("User")
.Include("OrderItems.Inventories.Product")
.Include("Transactions")
.Include("CustomerAddressBilling.Address")
.Include("CustomerAddressBilling.Customer")
.Include("CustomerAddressBilling.Contact")
.Include("CustomerAddressShipping.Address")
.Include("CustomerAddressShipping.Customer")
.Include("CustomerAddressShipping.Contact")
.Include("ShippingMethod")
// this works ok
let items = (o.OrderItems.Select(i => new Model.OrderItem
{
OrderItemId = i.OrderItemId,
OrderId = i.OrderId,
DateAdded = i.CreateDate,
LineItemPrice = i.Inventories.Sum(ii => ii.Product.Price),
Product = i.Inventories.FirstOrDefault().Product,
Quantity = i.Inventories.Count()
}))
// this works ok
let transactions = (o.Transactions.Select(t => new Model.Transaction
{
Id = t.TransactionId,
OrderId = t.OrderId,
Amount = t.Amount,
AuthorizationCode = t.AuthorizationCode,
DateExecuted = t.TransactionDate,
Notes = t.Notes,
Processor = (Model.TransactionProcessor)t.ProcessorId
}))
// this causes the error
let cab = o.CustAddBillingId.HasValue ? (new Model.CustomerAddress
{
Id = o.CustomerAddressBilling.CustAddId,
UserName = o.User.UserName,
FirstName = o.CustomerAddressBilling.Customer.FirstName,
LastName = o.CustomerAddressBilling.Customer.LastName,
MiddleInitial = o.CustomerAddressBilling.Customer.MiddleName,
Salutation = o.CustomerAddressBilling.Customer.Salutation,
Suffix = o.CustomerAddressBilling.Customer.Suffix,
Street1 = o.CustomerAddressBilling.Address.Line1,
Street2 = o.CustomerAddressBilling.Address.Line2,
Street3 = o.CustomerAddressBilling.Address.Line3,
City = o.CustomerAddressBilling.Address.City,
StateOrProvince = o.CustomerAddressBilling.Address.State,
Zip = o.CustomerAddressBilling.Address.PostalCode,
Country = o.CustomerAddressBilling.Address.Country,
Latitude = o.CustomerAddressBilling.Address.Lat,
Longitude = o.CustomerAddressBilling.Address.Long,
Email = o.CustomerAddressBilling.Contact.ContactInfo,
IsDefault = o.CustomerAddressBilling.IsPrimary
}) : default(Model.CustomerAddress)
// this causes the error
let cas = o.CustAddShippingId.HasValue ? (new Model.CustomerAddress
{
Id = o.CustomerAddressShipping.CustAddId,
UserName = o.User.UserName,
FirstName = o.CustomerAddressShipping.Customer.FirstName,
LastName = o.CustomerAddressShipping.Customer.LastName,
MiddleInitial = o.CustomerAddressShipping.Customer.MiddleName,
Salutation = o.CustomerAddressShipping.Customer.Salutation,
Suffix = o.CustomerAddressShipping.Customer.Suffix,
Street1 = o.CustomerAddressShipping.Address.Line1,
Street2 = o.CustomerAddressShipping.Address.Line2,
Street3 = o.CustomerAddressShipping.Address.Line3,
City = o.CustomerAddressShipping.Address.City,
StateOrProvince = o.CustomerAddressShipping.Address.State,
Zip = o.CustomerAddressShipping.Address.PostalCode,
Country = o.CustomerAddressShipping.Address.Country,
Latitude = o.CustomerAddressShipping.Address.Lat,
Longitude = o.CustomerAddressShipping.Address.Long,
Email = o.CustomerAddressShipping.Contact.ContactInfo,
IsDefault = o.CustomerAddressShipping.IsPrimary
}) : default(Model.CustomerAddress)
// this causes the error
let sm = o.ShippingMethodId.HasValue ? (new ShippingMethod
{
Id = o.ShippingMethod.ShippingMethodId,
Carrier = o.ShippingMethod.Carrier,
ServiceName = o.ShippingMethod.ServiceName,
BaseRate = o.ShippingMethod.BaseRate,
RatePerPound = o.ShippingMethod.RatePerPound,
DaysToDeliver = o.ShippingMethod.DaysToDeliver,
EstimatedDelivery = o.ShippingMethod.EstimatedDelivery
}) : default(ShippingMethod)
select new Model.Order
{
Id = o.OrderId,
UserName = o.User.UserName,
DateCreated = o.CreateDate,
Items = items.AsQueryable(),
Transactions = transactions.AsQueryable(),
ShippingAddressId = o.CustAddShippingId,
BillingAddressId = o.CustAddBillingId,
// have to comment these next 3 lines as well
ShippingAddress = cas,
BillingAddress = cab,
ShippingMethod = sm,
// to here
UserLanguageCode = "en",
DateShipped = o.ShippedDate,
EstimatedDelivery = o.EstimatedDelivery,
TrackingNumber = o.TrackingNumber,
TaxAmount = o.TaxAmount,
DiscountReason = o.DiscountReason,
DiscountAmount = o.DiscountAmount
};
最佳答案
好的，我已经弄明白了。问题是数据库允许那些相关实体的空外键，我更改了数据库，因此外键不可为空，并从数据库更新了模型。我创建了代表非 ShippingMethods 电子和面对面的新数据实体，并且还有面对面的 CustomerAddress，因此我可以链接到数据，这些数据不仅代表我没有数据，还代表我为什么没有数据。
public IQueryable<Model.Order> GetOrders()
{
var orders = from o in _db.Orders
.Include("User")
.Include("OrderItems.Inventories.Product")
.Include("Transactions")
.Include("CustomerAddressBilling.Address")
.Include("CustomerAddressBilling.Customer")
.Include("CustomerAddressBilling.Contact")
.Include("CustomerAddressShipping.Address")
.Include("CustomerAddressShipping.Customer")
.Include("CustomerAddressShipping.Contact")
.Include("ShippingMethod")
let items = (o.OrderItems.Select(i => new Model.OrderItem
{
OrderItemId = i.OrderItemId,
OrderId = i.OrderId,
DateAdded = i.CreateDate,
LineItemPrice = i.Inventories.Sum(ii => ii.Product.Price),
Product = i.Inventories.FirstOrDefault().Product,
Quantity = i.Inventories.Count()
}))
let transactions = (o.Transactions.Select(t => new Model.Transaction
{
Id = t.TransactionId,
OrderId = t.OrderId,
Amount = t.Amount,
AuthorizationCode = t.AuthorizationCode,
DateExecuted = t.TransactionDate,
Notes = t.Notes,
Processor = (Model.TransactionProcessor)t.ProcessorId
}))
let cab = new Model.CustomerAddress
{
Id = o.CustomerAddressBilling.CustAddId,
UserName = o.User.UserName,
FirstName = o.CustomerAddressBilling.Customer.FirstName,
LastName = o.CustomerAddressBilling.Customer.LastName,
MiddleInitial = o.CustomerAddressBilling.Customer.MiddleName,
Salutation = o.CustomerAddressBilling.Customer.Salutation,
Suffix = o.CustomerAddressBilling.Customer.Suffix,
Street1 = o.CustomerAddressBilling.Address.Line1,
Street2 = o.CustomerAddressBilling.Address.Line2,
Street3 = o.CustomerAddressBilling.Address.Line3,
City = o.CustomerAddressBilling.Address.City,
StateOrProvince = o.CustomerAddressBilling.Address.State,
Zip = o.CustomerAddressBilling.Address.PostalCode,
Country = o.CustomerAddressBilling.Address.Country,
Latitude = o.CustomerAddressBilling.Address.Lat,
Longitude = o.CustomerAddressBilling.Address.Long,
Email = o.CustomerAddressBilling.Contact.ContactInfo,
IsDefault = o.CustomerAddressBilling.IsPrimary
}
let cas = new Model.CustomerAddress
{
Id = o.CustomerAddressShipping.CustAddId,
UserName = o.User.UserName,
FirstName = o.CustomerAddressShipping.Customer.FirstName,
LastName = o.CustomerAddressShipping.Customer.LastName,
MiddleInitial = o.CustomerAddressShipping.Customer.MiddleName,
Salutation = o.CustomerAddressShipping.Customer.Salutation,
Suffix = o.CustomerAddressShipping.Customer.Suffix,
Street1 = o.CustomerAddressShipping.Address.Line1,
Street2 = o.CustomerAddressShipping.Address.Line2,
Street3 = o.CustomerAddressShipping.Address.Line3,
City = o.CustomerAddressShipping.Address.City,
StateOrProvince = o.CustomerAddressShipping.Address.State,
Zip = o.CustomerAddressShipping.Address.PostalCode,
Country = o.CustomerAddressShipping.Address.Country,
Latitude = o.CustomerAddressShipping.Address.Lat,
Longitude = o.CustomerAddressShipping.Address.Long,
Email = o.CustomerAddressShipping.Contact.ContactInfo,
IsDefault = o.CustomerAddressShipping.IsPrimary
}
let sm = new ShippingMethod
{
Id = o.ShippingMethod.ShippingMethodId,
Carrier = o.ShippingMethod.Carrier,
ServiceName = o.ShippingMethod.ServiceName,
BaseRate = o.ShippingMethod.BaseRate,
RatePerPound = o.ShippingMethod.RatePerPound,
DaysToDeliver = o.ShippingMethod.DaysToDeliver,
EstimatedDelivery = o.ShippingMethod.EstimatedDelivery
}
select new Model.Order
{
Id = o.OrderId,
UserName = o.User.UserName,
DateCreated = o.CreateDate,
Items = items.AsQueryable(),
Transactions = transactions.AsQueryable(),
ShippingAddressId = o.CustAddShippingId,
BillingAddressId = o.CustAddBillingId,
ShippingAddress = cas,
BillingAddress = cab,
ShippingMethod = sm,
UserLanguageCode = "en",
DateShipped = o.ShippedDate,
EstimatedDelivery = o.EstimatedDelivery,
TrackingNumber = o.TrackingNumber,
TaxAmount = o.TaxAmount,
DiscountReason = o.DiscountReason,
DiscountAmount = o.DiscountAmount
};
return orders;
}
没有错误!
关于c# - Linq to EF 系统不支持异常 System.NotSupportedException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15875339/