1
在這個例子中，我有一個Customer可以有很多PhoneNumbers。這些對象：綁定DataGrid到EntitySet
客戶
[Table(Name = "Customers")]
public class Customer : INotifyPropertyChanged
{
private String id;
private String givenName;
private String surname;
private EntitySet<PhoneNumber> phoneNumbers;
//INotifyPropertyChanged implementation was elided...
[Column(IsPrimaryKey=true, Storage="id", Name="Id", DbType="NVarChar(10) NOT NULL", CanBeNull=false)]
public String Id
{
get { return this.id; }
set
{
if (this.id != value)
{
this.id = value;
this.OnPropertyChanged("Id");
}
}
}
[Column(Storage="givenName", Name="GivenName", DbType="NVarChar(50) NOT NULL", CanBeNull=false)]
public String GivenName
{
get { return this.givenName; }
set
{
if (this.givenName != value)
{
this.givenName = value;
this.OnPropertyChanged("GivenName");
}
}
}
[Column(Storage="surname", Name="Surname", DbType="NVarChar(50) NOT NULL", CanBeNull=false)]
public String Surname
{
get { return this.surname; }
set
{
if (this.surname != value)
{
this.surname = value;
this.OnPropertyChanged("Surname");
}
}
}
[Association(Name="FK_PhoneBook_Customers", Storage = "phoneNumbers", ThisKey="Id", OtherKey = "CustomerId")]
public EntitySet<PhoneNumber> PhoneNumbers
{
get
{
return this.phoneNumbers;
}
set
{
if (this.phoneNumbers!= value)
{
this.phoneNumbers.Assign(value);
this.OnPropertyChanged("PhoneNumbers");
}
}
}
public Customer() { this.phoneNumbers = new EntitySet<PhoneNumber>(); }
}
和
[Table(Name = "PhoneBook")]
public class PhoneNumber: INotifyPropertyChanged
{
private int id;
private String customerId;
private String number;
private EntityRef<Customer> customer;
//INotifyPropertyChanged implementation was elided...
[Column(IsPrimaryKey=true, IsDbGenerated=true, Storage="id", Name="Id", DbType="int", CanBeNull=false)]
public int Id
{
get { return this.id; }
private set
{
if (this.id != value)
{
this.id = value;
this.OnPropertyChanged("Id");
}
}
}
[Column(Storage="customerId", Name="CustomerId", DbType="NVarChar(10) NOT NULL", CanBeNull=false)]
public String CustomerId
{
get { return this.customerId; }
set
{
if (this.customerId != value)
{
this.customerId = value;
this.OnPropertyChanged("CustomerId");
}
}
}
[Column(Storage="number", Name="Number", DbType="NVarChar(10) NOT NULL", CanBeNull=false)]
public String Number
{
get { return this.number; }
set
{
if (this.number != value)
{
this.number = value;
this.OnPropertyChanged("Number");
}
}
}
[Association(IsForeignKey=true, Name="FK_PhoneBook_Customers", ThisKey="CustomerId", OtherKey = "Id")]
public Customer Customer
{
get { return this.customer.Entity; }
set { this.customer.Entity = value; }
}
public PhoneNumber() { this.customer = new EntityRef<Customer>(); }
}
我創建了一個DataContext的，並得到了客戶（簡本）的電話號碼：
db = new DataContext(@"server=WIN-EL78137MUMS\SQLEXPRESS;database=SandBox;integrated security=SSPI");
// Get a typed table to run queries.
customers = db.GetTable<Customer>();
custQuery =
from cust in customers
orderby cust.Id
select cust;
Customer = custQuery.Skip(5).Take(1).First();
進入XAML我添加了DataGrid並將其綁定到CustomerNumber的PhoneNumbers屬性。
<DataGrid ItemsSource="{Binding PhoneNumbers}" AutoGenerateColumns="False">
<DataGrid.Columns>
<DataGridTextColumn Header="Id" Binding="{Binding Id, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" />
<DataGridTextColumn Header="CustomerId" Binding="{Binding CustomerId, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
<DataGridTextColumn Header="Number" Binding="{Binding Number, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
</DataGrid.Columns>
</DataGrid>
對不起長介紹，這裏是我的一些問題，以及問題 - 當我嘗試添加一個新的電話號碼輸入到電網，並調用db.SubmitChanges（）我得到以下錯誤信息：「試圖刪除Customer和PhoneNumber之間的關係，但是，其中一個關係的外鍵（PhoneNumber.CustomerId）不能設置爲null。「現在，我不希望用戶在需要添加電話號碼時不斷地寫入客戶ID，因爲正確的客戶已被選中，並且正在嘗試爲他的號碼集添加另一個號碼。這可以/應該如何完成？
其他問題是：
- 看來，新線不會被添加，直到輸入被按下，如果我輸入電話號碼，並在之後的是點擊一個按鈕調用db.SubmitChanges（），沒什麼會發生（所有三個集合[插入/更新/刪除]將爲空）。
- 我必須在PhoneNumber中保存一個EntityRef嗎？在野外有很多例子根本沒有，有人提到它是一對一的連接工具。
- 無論哪種方式，將EntityRef定義爲IsForeignKey = true都有點奇怪，聽起來對PhoneNumber.CustomerId應該定義爲ForeignKey更合理，但是當我試圖用[Association （IsForeignKey = true，Name =「FK_AddressBook_Customers」，ThisKey =「CustomerId」，OtherKey =「Id」）]我在應用程序啓動時出現此錯誤「無法找到類型爲'String'的鍵'Id'的鍵成員'Id' '。關鍵字可能是錯誤的，或'字符串'的字段或屬性已更改名稱「。我沒有在互聯網上找到任何有用的東西。它應該以另一種方式標記嗎？它應該被標記嗎？
- 我是否必須（或應該？）用兩個名稱（EntitySet和EntityRef）來命名外鍵（使用一個名稱（如我在另一個示例中看到的並在此處使用相同方法）？