c# - Entity Framework Core: `SqlNullValueException: Data is Null.` 如何排查？
问题描述
我在 ASP.NET Core 应用程序和控制器操作中使用 Entity Framework Core，我没有对工作代码或数据库进行任何更改，但我不知道 Entity Framework Core 执行的查询是什么。
控制器动作：
[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()
我什至试着做var companies = await DB.Companies.ToListAsync()。我有完全相同的例外。
也许我希望能够获取 EF Core 执行的查询以手动执行此操作，以便我可以尝试找出查询出了什么问题。
我想知道可能发生了什么。特别是因为其他实体（如用户或国家/地区）仍然可以从数据库中获取。
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东西，尽管它没有破坏代码中的引用，它似乎改变了 EF Core 以某种方式（疯狂猜测）解释数据库的方式。
我确实将我的 git 存储库重置到了 nuget 包更新发生并且一切正常之前的点。，。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 并最终得到相同的结果）并且问题再次发生......不确定 2.0.2 和 2.2 之间发生了什么变化。 0 触发此异常（但模型相同，只是更改了 EF Core 版本）...
这是实体定义，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（在项目文件中的 nuget 引用）有效
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.1.8" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.1.8" />
而那些，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" />
解决方案
错误消息表明 EF Core 正在尝试读取所需属性的string值，即在数据库中不应该有值的属性，而是底层数据读取器在某些记录中报告该属性的值。nullnull
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- 所有这些都[Required]在模型中标记为，但在表中没有相应not null的约束。
所以问题是由这些列中的一个或多个引起的。
您需要修复该差异 - 可能通过删除[Required]属性，因为现有数据中的约束已被破坏。
它在某些较旧的 EF Core 版本中“工作”的事实并不重要 - 这是不正确的映射，因此应该修复。从技术上讲，它不应该从一开始就起作用。但请记住，EF Core 仍在积极开发中，并且有许多错误将在下一个版本中修复。很可能在“工作”和“不工作”的 EF Core 版本之间进行了一些代码更改，从而修复了以前的不正确行为。
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