我正在编写一个无聊的应用程序来管理患者及其临床病史。我将 SQLite 与 DbLinq 库和 DbMetal 代码生成实用程序结合使用。以下是从底层数据库中提取的生成代码中的两个类：
[Table(Name="main.Patients")]
public partial class Patient : System.ComponentModel.INotifyPropertyChanging, System.ComponentModel.INotifyPropertyChanged
{
private static System.ComponentModel.PropertyChangingEventArgs emptyChangingEventArgs = new System.ComponentModel.PropertyChangingEventArgs("");
private long _birthday;
private string _firstName;
private int _hasChildren;
private System.Nullable<int> _id;
private int _isMarried;
private string _lastName;
private string _profession;
private EntitySet<ClinicCase> _clinicCases;
private EntitySet<PatientAddress> _patientsAddresses;
private EntitySet<PatientPhoneNumber> _patientsPhoneNumbers;
#region Extensibility Method Declarations
partial void OnCreated();
partial void OnBirthdayChanged();
partial void OnBirthdayChanging(long value);
partial void OnFirstNameChanged();
partial void OnFirstNameChanging(string value);
partial void OnHasChildrenChanged();
partial void OnHasChildrenChanging(int value);
partial void OnIDChanged();
partial void OnIDChanging(System.Nullable<int> value);
partial void OnIsMarriedChanged();
partial void OnIsMarriedChanging(int value);
partial void OnLastNameChanged();
partial void OnLastNameChanging(string value);
partial void OnProfessionChanged();
partial void OnProfessionChanging(string value);
#endregion
public Patient()
{
_clinicCases = new EntitySet<ClinicCase>(new Action<ClinicCase>(this.ClinicCases_Attach), new Action<ClinicCase>(this.ClinicCases_Detach));
_patientsAddresses = new EntitySet<PatientAddress>(new Action<PatientAddress>(this.PatientsAddresses_Attach), new Action<PatientAddress>(this.PatientsAddresses_Detach));
_patientsPhoneNumbers = new EntitySet<PatientPhoneNumber>(new Action<PatientPhoneNumber>(this.PatientsPhoneNumbers_Attach), new Action<PatientPhoneNumber>(this.PatientsPhoneNumbers_Detach));
this.OnCreated();
}
[Column(Storage="_birthday", Name="Birthday", DbType="integer", AutoSync=AutoSync.Never, CanBeNull=false)]
[DebuggerNonUserCode()]
public long BirthdayBinaryDate
{
get
{
return this._birthday;
}
set
{
if ((_birthday != value))
{
this.OnBirthdayChanging(value);
this.SendPropertyChanging();
this._birthday = value;
this.SendPropertyChanged("Birthday");
this.OnBirthdayChanged();
}
}
}
[Column(Storage="_firstName", Name="FirstName", DbType="text", AutoSync=AutoSync.Never, CanBeNull=false)]
[DebuggerNonUserCode()]
public string FirstName
{
get
{
return this._firstName;
}
set
{
if (((_firstName == value)
== false))
{
this.OnFirstNameChanging(value);
this.SendPropertyChanging();
this._firstName = value;
this.SendPropertyChanged("FirstName");
this.OnFirstNameChanged();
}
}
}
[Column(Storage="_hasChildren", Name="HasChildren", DbType="integer", AutoSync=AutoSync.Never, CanBeNull=false)]
[DebuggerNonUserCode()]
public int HasChildren
{
get
{
return this._hasChildren;
}
set
{
if ((_hasChildren != value))
{
this.OnHasChildrenChanging(value);
this.SendPropertyChanging();
this._hasChildren = value;
this.SendPropertyChanged("HasChildren");
this.OnHasChildrenChanged();
}
}
}
[Column(Storage="_id", Name="ID", DbType="integer", IsPrimaryKey=true, IsDbGenerated=true, AutoSync=AutoSync.OnInsert)]
[DebuggerNonUserCode()]
public System.Nullable<int> ID
{
get
{
return this._id;
}
set
{
if ((_id != value))
{
this.OnIDChanging(value);
this.SendPropertyChanging();
this._id = value;
this.SendPropertyChanged("ID");
this.OnIDChanged();
}
}
}
[Column(Storage="_isMarried", Name="IsMarried", DbType="integer", AutoSync=AutoSync.Never, CanBeNull=false)]
[DebuggerNonUserCode()]
public int IsMarried
{
get
{
return this._isMarried;
}
set
{
if ((_isMarried != value))
{
this.OnIsMarriedChanging(value);
this.SendPropertyChanging();
this._isMarried = value;
this.SendPropertyChanged("IsMarried");
this.OnIsMarriedChanged();
}
}
}
[Column(Storage="_lastName", Name="LastName", DbType="text", AutoSync=AutoSync.Never, CanBeNull=false)]
[DebuggerNonUserCode()]
public string LastName
{
get
{
return this._lastName;
}
set
{
if (((_lastName == value)
== false))
{
this.OnLastNameChanging(value);
this.SendPropertyChanging();
this._lastName = value;
this.SendPropertyChanged("LastName");
this.OnLastNameChanged();
}
}
}
[Column(Storage="_profession", Name="Profession", DbType="text", AutoSync=AutoSync.Never)]
[DebuggerNonUserCode()]
public string Profession
{
get
{
return this._profession;
}
set
{
if (((_profession == value)
== false))
{
this.OnProfessionChanging(value);
this.SendPropertyChanging();
this._profession = value;
this.SendPropertyChanged("Profession");
this.OnProfessionChanged();
}
}
}
#region Children
[Association(Storage="_clinicCases", OtherKey="PatientID", ThisKey="ID", Name="fk_ClinicCases_0")]
[DebuggerNonUserCode()]
public EntitySet<ClinicCase> ClinicCases
{
get
{
return this._clinicCases;
}
set
{
this._clinicCases = value;
}
}
[Association(Storage="_patientsAddresses", OtherKey="PatientID", ThisKey="ID", Name="fk_PatientsAddresses_0")]
[DebuggerNonUserCode()]
public EntitySet<PatientAddress> Addresses
{
get
{
return this._patientsAddresses;
}
set
{
this._patientsAddresses = value;
}
}
[Association(Storage="_patientsPhoneNumbers", OtherKey="PatientID", ThisKey="ID", Name="fk_PatientsPhoneNumbers_0")]
[DebuggerNonUserCode()]
public EntitySet<PatientPhoneNumber> PhoneNumbers
{
get
{
return this._patientsPhoneNumbers;
}
set
{
this._patientsPhoneNumbers = value;
}
}
#endregion
public event System.ComponentModel.PropertyChangingEventHandler PropertyChanging;
public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;
protected virtual void SendPropertyChanging()
{
System.ComponentModel.PropertyChangingEventHandler h = this.PropertyChanging;
if ((h != null))
{
h(this, emptyChangingEventArgs);
}
}
protected virtual void SendPropertyChanged(string propertyName)
{
System.ComponentModel.PropertyChangedEventHandler h = this.PropertyChanged;
if ((h != null))
{
h(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName));
}
}
#region Attachment handlers
private void ClinicCases_Attach(ClinicCase entity)
{
this.SendPropertyChanging();
entity.Patient = this;
}
private void ClinicCases_Detach(ClinicCase entity)
{
this.SendPropertyChanging();
entity.Patient = null;
}
private void PatientsAddresses_Attach(PatientAddress entity)
{
this.SendPropertyChanging();
entity.Patient = this;
}
private void PatientsAddresses_Detach(PatientAddress entity)
{
this.SendPropertyChanging();
entity.Patient = null;
}
private void PatientsPhoneNumbers_Attach(PatientPhoneNumber entity)
{
this.SendPropertyChanging();
entity.Patient = this;
}
private void PatientsPhoneNumbers_Detach(PatientPhoneNumber entity)
{
this.SendPropertyChanging();
entity.Patient = null;
}
#endregion
}
[Table(Name="main.PatientsAddresses")]
public partial class PatientAddress : System.ComponentModel.INotifyPropertyChanging, System.ComponentModel.INotifyPropertyChanged
{
private static System.ComponentModel.PropertyChangingEventArgs emptyChangingEventArgs = new System.ComponentModel.PropertyChangingEventArgs("");
private string _address;
private string _domicileStatus;
private System.Nullable<int> _patientID;
private EntityRef<Patient> _patients = new EntityRef<Patient>();
#region Extensibility Method Declarations
partial void OnCreated();
partial void OnAddressChanged();
partial void OnAddressChanging(string value);
partial void OnDomicileStatusChanged();
partial void OnDomicileStatusChanging(string value);
partial void OnPatientIDChanged();
partial void OnPatientIDChanging(System.Nullable<int> value);
#endregion
public PatientAddress()
{
this.OnCreated();
}
[Column(Storage="_address", Name="Address", DbType="text", IsPrimaryKey=true, AutoSync=AutoSync.Never)]
[DebuggerNonUserCode()]
public string Address
{
get
{
return this._address;
}
set
{
if (((_address == value)
== false))
{
this.OnAddressChanging(value);
this.SendPropertyChanging();
this._address = value;
this.SendPropertyChanged("Address");
this.OnAddressChanged();
}
}
}
[Column(Storage="_domicileStatus", Name="DomicileStatus", DbType="text", AutoSync=AutoSync.Never)]
[DebuggerNonUserCode()]
public string DomicileStatus
{
get
{
return this._domicileStatus;
}
set
{
if (((_domicileStatus == value)
== false))
{
this.OnDomicileStatusChanging(value);
this.SendPropertyChanging();
this._domicileStatus = value;
this.SendPropertyChanged("DomicileStatus");
this.OnDomicileStatusChanged();
}
}
}
[Column(Storage="_patientID", Name="PatientID", DbType="integer", IsPrimaryKey=true, IsDbGenerated=true, AutoSync=AutoSync.Never)]
[DebuggerNonUserCode()]
public System.Nullable<int> PatientID
{
get
{
return this._patientID;
}
set
{
if ((_patientID != value))
{
if (_patients.HasLoadedOrAssignedValue)
{
throw new System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException();
}
this.OnPatientIDChanging(value);
this.SendPropertyChanging();
this._patientID = value;
this.SendPropertyChanged("PatientID");
this.OnPatientIDChanged();
}
}
}
#region Parents
[Association(Storage="_patients", OtherKey="ID", ThisKey="PatientID", Name="fk_PatientsAddresses_0", IsForeignKey=true)]
[DebuggerNonUserCode()]
public Patient Patient
{
get
{
return this._patients.Entity;
}
set
{
if (((this._patients.Entity == value)
== false))
{
if ((this._patients.Entity != null))
{
Patient previousPatients = this._patients.Entity;
this._patients.Entity = null;
previousPatients.Addresses.Remove(this);
}
this._patients.Entity = value;
if ((value != null))
{
value.Addresses.Add(this);
_patientID = value.ID;
}
else
{
_patientID = null;
}
}
}
}
#endregion
public event System.ComponentModel.PropertyChangingEventHandler PropertyChanging;
public event System.ComponentModel.PropertyChangedEventHandler PropertyChanged;
protected virtual void SendPropertyChanging()
{
System.ComponentModel.PropertyChangingEventHandler h = this.PropertyChanging;
if ((h != null))
{
h(this, emptyChangingEventArgs);
}
}
protected virtual void SendPropertyChanged(string propertyName)
{
System.ComponentModel.PropertyChangedEventHandler h = this.PropertyChanged;
if ((h != null))
{
h(this, new System.ComponentModel.PropertyChangedEventArgs(propertyName));
}
}
}
我使用以下代码向患者添加地址：
PatientAddress address = new PatientAddress();
address.Address = txtAddress.Text;
address.DomicileStatus = cmbDomicileStatus.Text;
currentPatient.Addresses.Add(address);
Database.Source.PatientsAddresses.InsertOnSubmit(address);
Database.Source.SubmitChanges();
Database.Source 是在生成的代码中扩展 DataContext 的类的实例。在 SubmitChanges 上，我收到此异常：
“Nullable(Of Int32) 和 Int32 之间未定义等于运算符。”
消息不是一字不差地转述，但意思是一样的。堆栈跟踪指向 DbLinq 代码，更准确地说，指向源文件 DbLinq.Data.Linq.DataContext.cs 的第 709 行。您可以在这里找到源文件：http://dblinq.codeplex.com/SourceControl/changeset/view/16800#314775（在方法 SetEntityRefQueries(objectEntity) 的主体下）。 我发现在将外键值与表达式树中的常量进行比较时出现问题，但我无法获取有关该问题的其他信息。你能帮我找出问题所在吗？
注意：在调用 SubmitChanges 之前，字段 address.PatientID（外键）实际上已设置为正确的值。
正如我在上面的评论中提到的（我在这里重复，以便我可以链接图像），您的主键不应该为空。你的映射中应该有一个属性，你可以更改它来设置它，尽管我不使用 DbLinq，所以我不能直接给你它的屏幕截图。相反，它位于 LINQ-2-SQL DBML 设计器（左）和实体框架 EDMX 设计器（右）中。
我不太确定你的删除问题 - 这似乎对我有用。您可以编辑您的问题以包含整个删除代码块吗？作为初步猜测，您要么创建一个新对象（而不是加载对象），然后尝试删除它，要么删除关联而不删除该对象。
作为一般规则，当我可以避免时，我绝不会从数据库中删除 - 我只是将其标记为非活动状态。这样“取消删除”要容易得多。