5
Je suis en train de faire ce qui suit ...LINQ to SQL - Le cast spécifié n'est pas valide - SingleOrDefault()
Request request = (
from r in db.Requests
where r.Status == "Processing" && r.Locked == false
select r
).SingleOrDefault();
Il jette l'exception suivante ...
Message:
Specified cast is not valid.
StackTrace:
at System.Data.Linq.SqlClient.SqlProvider.Execute(Expression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult)
at System.Data.Linq.SqlClient.SqlProvider.ExecuteAll(Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries)
at System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query)
at System.Data.Linq.DataQuery`1.System.Linq.IQueryProvider.Execute[S](Expression expression)
at System.Linq.Queryable.SingleOrDefault[TSource](IQueryable`1 source)
at GDRequestProcessor.Worker.GetNextRequest()
Quelqu'un peut-il m'aider? Merci d'avance!
détails du schéma se trouvent ci-dessous ...
[Table(Name="dbo.Requests")]
public partial class Request : INotifyPropertyChanging, INotifyPropertyChanged
{
private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);
private int _RequestId;
private string _LoanNumber;
private string _ClientCode;
private int _RequestTypeId;
private bool _HasParameters;
private string _Status;
private bool _Locked;
private string _ErrorMessage;
private int _ReferenceId;
private EntitySet<RequestParameter> _RequestParameters;
private EntityRef<RequestType> _RequestType;
#region Extensibility Method Definitions
partial void OnLoaded();
partial void OnValidate(System.Data.Linq.ChangeAction action);
partial void OnCreated();
partial void OnRequestIdChanging(int value);
partial void OnRequestIdChanged();
partial void OnLoanNumberChanging(string value);
partial void OnLoanNumberChanged();
partial void OnClientCodeChanging(string value);
partial void OnClientCodeChanged();
partial void OnRequestTypeIdChanging(int value);
partial void OnRequestTypeIdChanged();
partial void OnHasParametersChanging(bool value);
partial void OnHasParametersChanged();
partial void OnStatusChanging(string value);
partial void OnStatusChanged();
partial void OnLockedChanging(bool value);
partial void OnLockedChanged();
partial void OnErrorMessageChanging(string value);
partial void OnErrorMessageChanged();
partial void OnReferenceIdChanging(int value);
partial void OnReferenceIdChanged();
#endregion
public Request()
{
this._RequestParameters = new EntitySet<RequestParameter>(new Action<RequestParameter>(this.attach_RequestParameters), new Action<RequestParameter>(this.detach_RequestParameters));
this._RequestType = default(EntityRef<RequestType>);
OnCreated();
}
[Column(Storage="_RequestId", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]
public int RequestId
{
get
{
return this._RequestId;
}
set
{
if ((this._RequestId != value))
{
this.OnRequestIdChanging(value);
this.SendPropertyChanging();
this._RequestId = value;
this.SendPropertyChanged("RequestId");
this.OnRequestIdChanged();
}
}
}
[Column(Storage="_LoanNumber", DbType="VarChar(50) NOT NULL", CanBeNull=false)]
public string LoanNumber
{
get
{
return this._LoanNumber;
}
set
{
if ((this._LoanNumber != value))
{
this.OnLoanNumberChanging(value);
this.SendPropertyChanging();
this._LoanNumber = value;
this.SendPropertyChanged("LoanNumber");
this.OnLoanNumberChanged();
}
}
}
[Column(Storage="_ClientCode", DbType="VarChar(50) NOT NULL", CanBeNull=false)]
public string ClientCode
{
get
{
return this._ClientCode;
}
set
{
if ((this._ClientCode != value))
{
this.OnClientCodeChanging(value);
this.SendPropertyChanging();
this._ClientCode = value;
this.SendPropertyChanged("ClientCode");
this.OnClientCodeChanged();
}
}
}
[Column(Storage="_RequestTypeId", DbType="Int NOT NULL")]
public int RequestTypeId
{
get
{
return this._RequestTypeId;
}
set
{
if ((this._RequestTypeId != value))
{
if (this._RequestType.HasLoadedOrAssignedValue)
{
throw new System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException();
}
this.OnRequestTypeIdChanging(value);
this.SendPropertyChanging();
this._RequestTypeId = value;
this.SendPropertyChanged("RequestTypeId");
this.OnRequestTypeIdChanged();
}
}
}
[Column(Storage="_HasParameters", DbType="Bit NOT NULL")]
public bool HasParameters
{
get
{
return this._HasParameters;
}
set
{
if ((this._HasParameters != value))
{
this.OnHasParametersChanging(value);
this.SendPropertyChanging();
this._HasParameters = value;
this.SendPropertyChanged("HasParameters");
this.OnHasParametersChanged();
}
}
}
[Column(Storage="_Status", DbType="VarChar(50) NOT NULL", CanBeNull=false)]
public string Status
{
get
{
return this._Status;
}
set
{
if ((this._Status != value))
{
this.OnStatusChanging(value);
this.SendPropertyChanging();
this._Status = value;
this.SendPropertyChanged("Status");
this.OnStatusChanged();
}
}
}
[Column(Storage="_Locked", DbType="Bit NOT NULL")]
public bool Locked
{
get
{
return this._Locked;
}
set
{
if ((this._Locked != value))
{
this.OnLockedChanging(value);
this.SendPropertyChanging();
this._Locked = value;
this.SendPropertyChanged("Locked");
this.OnLockedChanged();
}
}
}
[Column(Storage="_ErrorMessage", DbType="VarChar(255)")]
public string ErrorMessage
{
get
{
return this._ErrorMessage;
}
set
{
if ((this._ErrorMessage != value))
{
this.OnErrorMessageChanging(value);
this.SendPropertyChanging();
this._ErrorMessage = value;
this.SendPropertyChanged("ErrorMessage");
this.OnErrorMessageChanged();
}
}
}
[Column(Storage="_ReferenceId", DbType="Int NOT NULL")]
public int ReferenceId
{
get
{
return this._ReferenceId;
}
set
{
if ((this._ReferenceId != value))
{
this.OnReferenceIdChanging(value);
this.SendPropertyChanging();
this._ReferenceId = value;
this.SendPropertyChanged("ReferenceId");
this.OnReferenceIdChanged();
}
}
}
Cela se produit généralement lorsque le type d'une ou de plusieurs propriétés de l'objet C# ne correspond pas au type de la colonne. pouvez-vous publier le schéma pour la table Request et les types pour les propriétés de la classe Request? –
Quel est le type de demande? Que faire si vous utilisez une requête var? Quel est le type de retour de SingleOrDefault? –
La demande reflète un enregistrement dans la table de base de données Requêtes ... J'ai essayé d'utiliser le code ci-dessous et ai toujours l'erreur ... var query = (de r dans db.Request où r.Status.Equals ("Processing") && r.Locked.Equals (false) sélectionnez r) .SingleOrDefault(); le type de retour de SingleOrDefault est la demande – NullReference