实体框架核心：‘`SqlNullValueException: Data is Null.`如何排除故障？
实体框架核心：‘`SqlNullValueException: Data is Null.`如何排除故障？
提问于 2019-04-27 18:36:17
我在ASP.NET核心应用程序和控制器操作中使用实体框架核心，我没有将某些内容更改为工作代码或数据库，但我无法判断实体框架核心执行的查询是什么。
主计长的行动：
[HttpGet]
// GET: Administration/Companies
public async Task<ActionResult> Index()
{
var users = await UserManager.Users.ToListAsync();
var companyEditVMs = await DB.Companies
.OrderBy(company => company.CompanyId == 1
? "_" + company.CompanyName
: company.CompanyName
)
Select(a => new CompanyEditVM(HttpContext, a, users.Where(b => b.CompanyId == a.CompanyId)))
.ToListAsync();
return View(companyEditVMs);
}痕迹
SqlNullValueException: Data is Null. This method or property cannot be called on Null values.
System.Data.SqlClient.SqlBuffer.get_String()
System.Data.SqlClient.SqlDataReader.GetString(int i)
lambda_method(Closure , DbDataReader )
Microsoft.EntityFrameworkCore.Storage.Internal.TypedRelationalValueBufferFactory.Create(DbDataReader dataReader)
Microsoft.EntityFrameworkCore.Query.Internal.AsyncQueryingEnumerable<T>+AsyncEnumerator.BufferlessMoveNext(DbContext _, bool buffer, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync<TState, TResult>(TState state, Func<DbContext, TState, CancellationToken, Task<TResult>> operation, Func<DbContext, TState, CancellationToken, Task<ExecutionResult<TResult>>> verifySucceeded, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Query.Internal.AsyncQueryingEnumerable<T>+AsyncEnumerator.MoveNext(CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Query.Internal.AsyncLinqOperatorProvider+ExceptionInterceptor<T>+EnumeratorExceptionInterceptor.MoveNext(CancellationToken cancellationToken)
System.Linq.AsyncEnumerable.Aggregate_<TSource, TAccumulate, TResult>(IAsyncEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> accumulator, Func<TAccumulate, TResult> resultSelector, CancellationToken cancellationToken) in Aggregate.cs
KYC.Core.Areas.Commercial.Controllers.CompaniesController.Index() in CompaniesController.cs
-
[HttpGet]
// GET: Administration/Companies
public async Task<ActionResult> Index()
{
var users = await UserManager.Users.ToListAsync();
var companyEditVMs = await DB.Companies
.OrderBy(company => company.CompanyId == 1
? "_" + company.CompanyName
: company.CompanyName
)
.Select(a => new CompanyEditVM(HttpContext, a, users.Where(b => b.CompanyId == a.CompanyId)))
.ToListAsync();
lambda_method(Closure , object )
Microsoft.Extensions.Internal.ObjectMethodExecutorAwaitable+Awaiter.GetResult()
Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor+TaskOfActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, object controller, object[] arguments)
System.Threading.Tasks.ValueTask<TResult>.get_Result()我甚至试着只做var companies = await DB.Companies.ToListAsync()。我也有同样的例外。
也许我希望能够获取EF Core执行的查询来手动执行，这样我就可以尝试找出查询的错误所在。
我想知道可能会发生什么。特别是因为其他实体，如用户或国家，仍然可以从数据库中获取。
我知道如何解决实际的潜在问题吗？
编辑
“代码”中唯一真正改变的是nuget引用，我基本上升级了几乎所有的东西，尽管它没有破坏代码中的引用--它似乎改变了EF Core在某种程度上解释数据库的方式。
我确实重置了我的git存储库，就在nuget包更新发生之前，事情就发生了。然后，我决定将EntityFrameworkCore从2.0.2更新到2.2.4 (也尝试使用2.2.0并得到相同的结果)，这个问题再次发生.不确定在2.0.2和2.2.0之间发生了什么变化来触发这个异常(但是模型是相同的，只是EF核心版本改变了).
下面是实体定义，它似乎是使用数据库表/模式中的工具自动生成的：
[Table("T_Companies")]
public partial class Company : INotifyPropertyChanging, INotifyPropertyChanged
{
public override string ToString()
{
return CompanyId + " " + CompanyName;
}
private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(string.Empty);
private int _CompanyId;
private string _CompanyName;
private int _CompanyTypeId;
private int _CountryId;
private string _CompanyVatNumber;
private string _CompanyStreetAddress;
private string _CompanyZipCode;
private string _CompanyCity;
private string _ContactLastName;
private string _ContactFirstName;
private bool? _Active;
private int? _AccountId;
private string _CallbackSalt;
private int? _UserSpaceId;
private string _Login;
private string _Pwd;
private bool _IsTechnicalAccount;
private DateTime? _StatusDate;
private int _BankStatusCode;
private string _PivotalAccount;
private CompanyType _CompanyType;
private Country _Country;
private bool _IsKycIdSent;
#region Extensibility Method Definitions
partial void OnLoaded();
partial void OnCreated();
partial void OnCompanyIdChanging(int value);
partial void OnCompanyIdChanged();
partial void OnCompanyNameChanging(string value);
partial void OnCompanyNameChanged();
partial void OnCompanyCityChanging(string value);
partial void OnCompanyCityChanged();
partial void OnCompanyZipCodeChanging(string value);
partial void OnCompanyZipCodeChanged();
partial void OnContactLastNameChanging(string value);
partial void OnContactLastNameChanged();
partial void OnActiveChanging(bool? value);
partial void OnActiveChanged();
partial void OnCompanyTypeIdChanging(int value);
partial void OnCompanyTypeIdChanged();
partial void OnCountryIdChanging(int value);
partial void OnCountryIdChanged();
partial void OnContactFirstNameChanging(string value);
partial void OnContactFirstNameChanged();
partial void OnCompanyVatNumberChanging(string value);
partial void OnCompanyVatNumberChanged();
partial void OnCompanyStreetAddressChanged();
partial void OnCompanyStreetAddressChanging(string value);
partial void OnAccountIdChanging(int? value);
partial void OnAccountIdChanged();
partial void OnCallbackSaltChanging(string value);
partial void OnCallbackSaltChanged();
partial void OnUserSpaceIdChanging(int? value);
partial void OnUserSpaceIdChanged();
partial void OnLoginChanging(string value);
partial void OnLoginChanged();
partial void OnPwdChanging(string value);
partial void OnPwdChanged();
partial void OnIsTechnicalAccountChanging(bool value);
partial void OnIsTechnicalAccountChanged();
partial void OnStatusDateChanging(DateTime? value);
partial void OnStatusDateChanged();
partial void OnBankStatusCodeChanging(int value);
partial void OnBankStatusCodeChanged();
partial void OnPivotalAccountChanging(string value);
partial void OnPivotalAccountChanged();
partial void OnIsKycIdSentChanging(bool value);
partial void OnIsKycIdSentChanged();
#endregion
public Company()
{
OnCreated();
}
[Key, Column("CompanyId"), DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int CompanyId
{
get => _CompanyId;
set
{
if (_CompanyId != value)
{
OnCompanyIdChanging(value);
SendPropertyChanging();
_CompanyId = value;
SendPropertyChanged("CompanyId");
OnCompanyIdChanged();
}
}
}
[DataType(DataType.Text), StringLength(1024), Column("CompanyName"), Required]
public string CompanyName
{
get => _CompanyName;
set
{
if (_CompanyName != value)
{
OnCompanyNameChanging(value);
SendPropertyChanging();
_CompanyName = value;
SendPropertyChanged("CompanyName");
OnCompanyNameChanged();
}
}
}
[Column("CompanyTypeId"), Required]
public int CompanyTypeId
{
get => _CompanyTypeId;
set
{
if (_CompanyTypeId != value)
{
OnCompanyTypeIdChanging(value);
SendPropertyChanging();
_CompanyTypeId = value;
SendPropertyChanged("CompanyTypeId");
OnCompanyTypeIdChanged();
}
}
}
[Column("CountryId"), Required]
public int CountryId
{
get => _CountryId;
set
{
if (CountryId != value)
{
OnCountryIdChanging(value);
SendPropertyChanging();
_CountryId = value;
SendPropertyChanged("CountryId");
OnCountryIdChanged();
}
}
}
[DataType(DataType.Text), StringLength(100), Column("CompanyCity"), Required]
public string CompanyCity
{
get => _CompanyCity;
set
{
if (_CompanyCity != value)
{
OnCompanyCityChanging(value);
SendPropertyChanging();
_CompanyCity = value;
SendPropertyChanged("CompanyCity");
OnCompanyCityChanged();
}
}
}
[DataType(DataType.Text), StringLength(100), Column("CompanyStreetAddress"), Required]
public string CompanyStreetAddress
{
get => _CompanyStreetAddress;
set
{
if (_CompanyStreetAddress != value)
{
OnCompanyStreetAddressChanging(value);
SendPropertyChanging();
_CompanyStreetAddress = value;
SendPropertyChanged("CompanyStreetAddress");
OnCompanyStreetAddressChanged();
}
}
}
[DataType(DataType.Text), StringLength(30), Column("CompanyVatNumber"), Required]
public string CompanyVatNumber
{
get => _CompanyVatNumber;
set
{
if (_CompanyVatNumber != value)
{
OnCompanyVatNumberChanging(value);
SendPropertyChanging();
_CompanyVatNumber = value;
SendPropertyChanged("CompanyVatNumber");
OnCompanyVatNumberChanged();
}
}
}
[DataType(DataType.Text), StringLength(10), Column("CompanyZipCode"), Required]
public string CompanyZipCode
{
get => _CompanyZipCode;
set
{
if (_CompanyZipCode != value)
{
OnCompanyZipCodeChanging(value);
SendPropertyChanging();
_CompanyZipCode = value;
SendPropertyChanged("CompanyZipCode");
OnCompanyZipCodeChanged();
}
}
}
[DataType(DataType.Text), StringLength(1024), Column("ContactLastName"), Required]
public string ContactLastName
{
get => _ContactLastName;
set
{
if (_ContactLastName != value)
{
OnContactLastNameChanging(value);
SendPropertyChanging();
_ContactLastName = value;
SendPropertyChanged("ContactLastName");
OnContactLastNameChanged();
}
}
}
[DataType(DataType.Text), StringLength(1024), Column("ContactFirstName"), Required]
public string ContactFirstName
{
get => _ContactFirstName;
set
{
if (_ContactFirstName != value)
{
OnContactFirstNameChanging(value);
SendPropertyChanging();
_ContactFirstName = value;
SendPropertyChanged("ContactFirstName");
OnContactFirstNameChanged();
}
}
}
[Column("Active"), Required]
public bool? Active
{
get => _Active;
set
{
if (_Active != value)
{
OnActiveChanging(value);
SendPropertyChanging();
_Active = value;
SendPropertyChanged("Active");
OnActiveChanged();
}
}
}
[Column("AccountId")]
public int? AccountId
{
get => _AccountId;
set
{
if (_AccountId != value)
{
OnAccountIdChanging(value);
SendPropertyChanging();
_AccountId = value;
SendPropertyChanged("AccountId");
OnAccountIdChanged();
}
}
}
[DataType(DataType.Text), StringLength(1024), Column("CallbackSalt")]
public string CallbackSalt
{
get => _CallbackSalt;
set
{
if (_CallbackSalt != value)
{
OnCallbackSaltChanging(value);
SendPropertyChanging();
_CallbackSalt = value;
SendPropertyChanged("CallbackSalt");
OnCallbackSaltChanged();
}
}
}
[Column("UserSpaceId")]
public int? UserSpaceId
{
get => _UserSpaceId;
set
{
if (_UserSpaceId != value)
{
OnUserSpaceIdChanging(value);
SendPropertyChanging();
_UserSpaceId = value;
SendPropertyChanged("UserSpaceId");
OnUserSpaceIdChanged();
}
}
}
[DataType(DataType.Text), StringLength(1024), Column("Login")]
public string Login
{
get => _Login;
set
{
if (_Login != value)
{
OnLoginChanging(value);
SendPropertyChanging();
_Login = value;
SendPropertyChanged("Login");
OnLoginChanged();
}
}
}
[DataType(DataType.Text), StringLength(1024), Column("Pwd")]
public string Pwd
{
get => _Pwd;
set
{
if (_Pwd != value)
{
OnPwdChanging(value);
SendPropertyChanging();
_Pwd = value;
SendPropertyChanged("Pwd");
OnPwdChanged();
}
}
}
[Column("IsTechnicalAccount"), Required]
public bool IsTechnicalAccount
{
get => _IsTechnicalAccount;
set
{
if (_IsTechnicalAccount != value)
{
OnIsTechnicalAccountChanging(value);
SendPropertyChanging();
_IsTechnicalAccount = value;
SendPropertyChanged("IsTechnicalAccount");
OnIsTechnicalAccountChanged();
}
}
}
[DataType(DataType.DateTime), Column("StatusDate")]
public DateTime? StatusDate
{
get => _StatusDate;
set
{
if (_StatusDate != value)
{
OnStatusDateChanging(value);
SendPropertyChanging();
_StatusDate = value;
SendPropertyChanged("StatusDate");
OnStatusDateChanged();
}
}
}
[Column("BankStatusCode")]
public int BankStatusCode
{
get => _BankStatusCode;
set
{
if (_BankStatusCode != value)
{
OnBankStatusCodeChanging(value);
SendPropertyChanging();
_BankStatusCode = value;
SendPropertyChanged("BankStatusCode");
OnBankStatusCodeChanged();
}
}
}
[DataType(DataType.Text), StringLength(255), Column("PivotalAccount")]
public string PivotalAccount
{
get => _PivotalAccount;
set
{
if (_PivotalAccount != value)
{
OnPivotalAccountChanging(value);
SendPropertyChanging();
_PivotalAccount = value;
SendPropertyChanged("PivotalAccount");
OnPivotalAccountChanged();
}
}
}
public List<Resultat> Resultats { get; set; }
public CompanyType CompanyType
{
get => _CompanyType;
set
{
var previousValue = _CompanyType;
if (previousValue != value)
{
SendPropertyChanging();
_CompanyType = value;
if (value != null)
{
CompanyTypeId = value.CompanyTypeId;
}
else
{
_CompanyTypeId = default;
}
SendPropertyChanged("CompanyType");
}
}
}
public Country Country
{
get => _Country;
set
{
var previousValue = _Country;
if (previousValue != value)
{
SendPropertyChanging();
_Country = value;
_CountryId = value?.CountryId ?? default;
SendPropertyChanged("Country");
}
}
}
[Column("IsKycIdSent"), Required]
public bool IsKycIdSent
{
get => _IsKycIdSent;
set
{
if (_IsKycIdSent != value)
{
OnIsKycIdSentChanging(value);
SendPropertyChanging();
_IsKycIdSent = value;
SendPropertyChanged("IsKycIdSent");
OnIsKycIdSentChanged();
}
}
}
public event PropertyChangingEventHandler PropertyChanging;
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void SendPropertyChanging()
{
PropertyChanging?.Invoke(this, emptyChangingEventArgs);
}
protected virtual void SendPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
private void Attach_Resultats(Resultat entity)
{
SendPropertyChanging();
entity.Company = this;
}
private void Detach_Resultats(Resultat entity)
{
SendPropertyChanging();
entity.Company = null;
}
}以及相关的表创建脚本：
create table T_Companies
(
CompanyId int identity (10) identity
primary key nonclustered,
CompanyName varchar(1024) not null,
CompanyTypeId int not null
constraint FK_Company_CompanyType
references T_CompanyTypes,
CountryId int not null
constraint FK_Company_Country
references T_Countries,
Active bit not null,
AccountId int,
CallbackSalt varchar(1024),
UserSpaceId int,
Login varchar(1024),
Pwd varchar(1024),
StatusDate datetime(23, 3),
BankStatusCode int not null,
PivotalAccount varchar(255),
IsTechnicalAccount bit not null,
CompanyStreetAddress varchar(256),
CompanyCity varchar(256),
CompanyZipCode varchar(10),
CompanyVatNumber varchar(30),
ContactFirstName varchar(20),
ContactLastName varchar(20),
IsKycIdSent bit not null
)
go编辑2
对于相同的模型，这个(在nuget引用的项目文件中)可以工作。
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.1.8" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.1.8" />而那些人，不：
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.2.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.2.0" /><PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.2.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.1.8" />回答 12
Stack Overflow用户
回答已采纳
发布于 2019-04-28 11:38:28
错误消息表明，error试图为必需的属性读取值，即数据库中永远不应该有null值的属性，但是底层数据读取器在某些记录中报告该属性的null值。
查看您的实体模型和相应的数据库表，您可以看到许多string属性-> varchar列的明显差异。CompanyStreetAddress、CompanyCity、CompanyZipCode、CompanyVatNumber、ContactFirstName、ContactLastName -所有这些在模型中都标记为[Required]，但在表中没有相应的not null约束。
所以问题是由这些列中的一个或多个引起的。
您需要解决这个差异--可能是通过删除[Required]属性来解决的，因为现有数据中的约束已经被破坏了。
事实上，它在一些旧的EF核心版本中“工作”并不重要--这是不正确的映射，因此应该加以修正。从技术上讲，从一开始就不应该起作用。但是请记住，EF仍在积极开发中，并且有许多bug在下一个版本中得到了修复。最有可能的是，在“工作”和“非工作”EF核心版本之间进行了一些代码更改，修复了之前的错误行为。
Stack Overflow用户
发布于 2019-11-13 14:23:13
如果您试图从数据库中读取一些可空数据，但您的类型不能为空，则可以获得此错误。
如果MyInt在数据库中是可空的，并且您有以下实体：
public class MyEntity
{
public int Id { get; set; }
public int MyInt { get; set; }
}您将得到异常：System.Data.SqlTypes.SqlNullValueException: 'Data is Null. This method or property cannot be called on Null values.'
要解决这个问题，只需将MyInt属性的类型更改为Nullable<int>或int?
public class MyEntity
{
public int Id { get; set; }
public int? MyInt { get; set; }
}注:这不是对原来问题的回答，而是对标题中问题的回答。
Stack Overflow用户
发布于 2020-02-29 18:13:59
如果您从C# 8中启用了最新的可空特性，也会出现这种异常。
EF，至少目前，它不完全兼容C# 8可空类型。因此，例如，假设您为项目启用了Nullable特性，如果您有如下类型：
public class MyEntity
{
public string MyProperty { get; set; }
}即使属性是而不是用所需属性标记的，EF核心也会引发这种异常，因为它要求数据库中的值不为null (也就是说，它不使用IsDbNull测试列值)。
有关如何在EF核心中处理可空引用类型的更多信息，请参见：https://learn.microsoft.com/en-us/ef/core/miscellaneous/nullable-reference-types
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/55883704
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