This is a problem that I have been having a lot of trouble with and would be so grateful for some help.
这是一个我遇到很多麻烦的问题,非常感谢一些帮助。
I have created a 'NewPurchases' API that is linked to a Customer ID and Handset ID. However, when I manually populate the 'Purchases' table in the database and check the GET functionality of this API on POSTMAN, it returns null values for Customer and Handset ID:
我创建了一个链接到客户ID和手机ID的“NewPurchases”API。但是,当我手动填充数据库中的“Purchases”表并在POSTMAN上检查此API的GET功能时,它会返回Customer和Handset ID的空值:
<Purchase>
<CommissionGenerated>100</CommissionGenerated>
<Customer i:nil="true"/>
<DatePurchased>2018-02-15T00:00:00</DatePurchased>
<Handset i:nil="true"/>
<Id>3</Id>
</Purchase>
Additionally, when I attempt to POST on POSTMAN, I get a 500 Internal Server Error "Unable to create a null constant value of type 'System.Collections.Generic.List....Only entity types, enumeration types or primitive types are supported in this context."
此外,当我尝试在POSTMAN上POST时,我得到500内部服务器错误“无法创建类型为'System.Collections.Generic.List的空常量值....仅支持实体类型,枚举类型或基元类型在这方面。“
Here is my NewPurchaseDto:
这是我的NewPurchaseDto:
public int CustomerId { get; set; }
public List<int> HandsetIds { get; set; }
And here is my NewPurchasesController (Api Controller):
这是我的NewPurchasesController(Api控制器):
public class NewPurchasesController : ApiController
{
private ApplicationDbContext _context;
public NewPurchasesController()
{
_context = new ApplicationDbContext();
}
// Get Api/NewPurchases
public IHttpActionResult GetHandsets(NewPurchaseDto newPurchase)
{
var handsetsQuery = _context.Purchases.ToList();
return Ok(handsetsQuery);
}
[HttpPost]
public IHttpActionResult CreateNewPurchases(NewPurchaseDto newPurchase)
{
var customer = _context.Customers.Single(
c => c.Id == newPurchase.CustomerId);
var handsets = _context.Handsets.Where(
m => newPurchase.HandsetIds.Contains(m.Id)).ToList();
foreach (var handset in handsets)
{
var purchase = new Purchase
{
Customer = customer,
Handset = handset,
DatePurchased = DateTime.Now
};
_context.Purchases.Add(purchase);
}
_context.SaveChanges();
return Ok();
}
}
}
Additionally, here are my Customer and Handset models:
此外,这是我的客户和手机型号:
public class Customer
{
public int Id { get; set;}
[Required]
[StringLength(255)]
public string Name { get; set; }
public bool IsSubscribedToInsurance { get; set; }
[Display(Name = "Account Type")]
public AccountType AccountType { get; set; }
public byte AccountTypeId { get; set; }
[Display(Name = "Date of Birth")]
[Min18YearsIfAContract]
public DateTime? Birthdate { get; set; }
}
public class Handset
{
public int Id { get; set; }
[Required]
[StringLength(255)]
public string Name { get; set; }
public Manufacturer Manufacturer { get; set; }
[Display(Name = "Manufacturer")]
[Required]
public byte ManufacturerId { get; set; }
public DateTime DateAdded { get; set; }
[Display(Name = "Release Date")]
public DateTime ReleaseDate { get; set; }
[Display(Name = "Number in Stock")]
[Range(1, 25)]
public byte NumberInStock { get; set; }
}
I really would love to get to the bottom of this, thanks in advance!
我真的很想深究这一点,提前谢谢!
1 个解决方案
#1
0
The API and parameters look fine and I can get into the action when I pass:
API和参数看起来很好,我可以在通过时进入操作:
{
customerId: 123,
handsetIds: [1,2,3]
}
So it's failing inside CreateNewPurchases
. I suspect the line
所以它在CreateNewPurchases中失败了。我怀疑这条线
var handsets = _context.Handsets.Where(
m => newPurchase.HandsetIds.Contains(m.Id)).ToList();
is failing because you are searching for handsets in the database where they are in a null List<>
of Ids, and SQL can't convert that.
失败是因为您正在数据库中搜索它们位于Ids的空List <>中的手机,并且SQL无法转换它。
Change the line to
将行更改为
var handsets = _context.Handsets.Where(
m => newPurchase.HandsetIds.Any(np => np == m.Id));
#1
0
The API and parameters look fine and I can get into the action when I pass:
API和参数看起来很好,我可以在通过时进入操作:
{
customerId: 123,
handsetIds: [1,2,3]
}
So it's failing inside CreateNewPurchases
. I suspect the line
所以它在CreateNewPurchases中失败了。我怀疑这条线
var handsets = _context.Handsets.Where(
m => newPurchase.HandsetIds.Contains(m.Id)).ToList();
is failing because you are searching for handsets in the database where they are in a null List<>
of Ids, and SQL can't convert that.
失败是因为您正在数据库中搜索它们位于Ids的空List <>中的手机,并且SQL无法转换它。
Change the line to
将行更改为
var handsets = _context.Handsets.Where(
m => newPurchase.HandsetIds.Any(np => np == m.Id));