AssociationAttribute Class

Reference

Definition

Namespace:: System.Data.Linq.Mapping

Assembly:: System.Data.Linq.dll

Important

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Designates a property to represent a database association, such as a foreign key relationship.

public ref class AssociationAttribute sealed : System::Data::Linq::Mapping::DataAttribute

[System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Property, AllowMultiple=false)]
public sealed class AssociationAttribute : System.Data.Linq.Mapping.DataAttribute

[<System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Property, AllowMultiple=false)>]
type AssociationAttribute = class
    inherit DataAttribute

Public NotInheritable Class AssociationAttribute
Inherits DataAttribute

Inheritance: Object

Attribute

DataAttribute
AssociationAttribute

Attributes: AttributeUsageAttribute

Examples

private EntityRef<Customer> _Customer;
// ...
[Association(Name="FK_Orders_Customers", Storage="_Customer", ThisKey="CustomerID", IsForeignKey=true)]
public Customer Customer
{
    get
    {
        return this._Customer.Entity;
    }
    set
    {
        Customer previousValue = this._Customer.Entity;
        if (((previousValue != value)
                    || (!this._Customer.HasLoadedOrAssignedValue )))
        {
            this.SendPropertyChanging();
            if ((previousValue != null))
            {
                this._Customer.Entity = null;
                previousValue.Orders.Remove(this);
            }
            this._Customer.Entity = value;
            if ((value != null))
            {
                value.Orders.Add(this);
                this._CustomerID = value.CustomerID;
            }
            else
            {
                this._CustomerID = default(string);
            }
            this.SendPropertyChanged("Customer");
        }
    }
}

Private _Customer As EntityRef(Of Customer)
<Association(Name:="FK_Orders_Customers", Storage:="_Customer", ThisKey:="CustomerID", IsForeignKey:=True)> _
Public Property Customer() As Customer
    Get
        Return Me._Customer.Entity
    End Get
    Set(ByVal value As Customer)
        Dim previousValue As Customer = Me._Customer.Entity
        If (((previousValue Is value) _
           = False) _
           OrElse (Me._Customer.HasLoadedOrAssignedValue = False)) Then
            Me.SendPropertyChanging()
            If ((previousValue Is Nothing) _
               = False) Then
                Me._Customer.Entity = Nothing
                previousValue.Orders.Remove(Me)
            End If
            Me._Customer.Entity = value
            If ((value Is Nothing) _
               = False) Then
                value.Orders.Add(Me)
                Me._CustomerID = value.CustomerID
            Else
                Me._CustomerID = CType(Nothing, String)
            End If
            Me.SendPropertyChanged("Customer")
        End If
    End Set
End Property

Remarks

Use this attribute to represent an association in a database, such as the relationship between a foreign key and a primary key.

In the following example, the Order class includes an AssociationAttribute attribute to associate Orders with Customers.

Constructors

AssociationAttribute()

Initializes a new instance of the AssociationAttribute class.

Properties

DeleteOnNull	When placed on a 1:1 association whose foreign key members are all non-nullable, deletes the object when the association is set to null.
DeleteRule	Gets or sets delete behavior for an association.
IsForeignKey	Gets or sets the member as the foreign key in an association representing a database relationship.
IsUnique	Gets or sets the indication of a uniqueness constraint on the foreign key.
Name	Gets or sets the name of a column. (Inherited from DataAttribute)
OtherKey	Gets or sets one or more members of the target entity class as key values on the other side of the association.
Storage	Gets or sets a private storage field to hold the value from a column. (Inherited from DataAttribute)
ThisKey	Gets or sets members of this entity class to represent the key values on this side of the association.
TypeId	When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute)

Methods

Equals(Object)	Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute)
GetHashCode()	Returns the hash code for this instance. (Inherited from Attribute)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsDefaultAttribute()	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute)
Match(Object)	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)

Explicit Interface Implementations

_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)	Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute)
_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)	Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute)
_Attribute.GetTypeInfoCount(UInt32)	Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute)
_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)	Provides access to properties and methods exposed by an object. (Inherited from Attribute)

Applies to

Dela via