LinqToEntitiesDomainService 泛型类

项目
03/18/2011

提供对 LINQ to Entities 数据模型执行操作的域服务的基类。

命名空间: System.ServiceModel.DomainServices.EntityFramework
程序集： System.ServiceModel.DomainServices.EntityFramework（在 system.servicemodel.domainservices.entityframework.dll 中）

用法

用法
Dim instance As LinqToEntitiesDomainService(Of TContext)

语法

声明
<LinqToEntitiesDomainServiceDescriptionProviderAttribute> _
Public MustInherit Class LinqToEntitiesDomainService(Of TContext As ObjectContext)
    Inherits DomainService

[LinqToEntitiesDomainServiceDescriptionProviderAttribute] 
public abstract class LinqToEntitiesDomainService<TContext> : DomainService where TContext : ObjectContext

[LinqToEntitiesDomainServiceDescriptionProviderAttribute] 
generic<typename TContext> where TContext : ObjectContext
public ref class LinqToEntitiesDomainService abstract : public DomainService

GenericParameters

TContext
LINQ to Entities 的类型 ObjectContext。

示例

下面的示例演示了派生自 LinqToEntitiesDomainService 的域服务。其中包含用于查询、更新和删除数据的方法。

<EnableClientAccess()>  _
Public Class OrderDomainService
    Inherits LinqToEntitiesDomainService(Of AdventureWorksLT_DataEntities)

    Public Function GetSalesOrders() As IQueryable(Of SalesOrderHeader)
        Return Me.ObjectContext.SalesOrderHeaders.Include("SalesOrderDetails")
    End Function
    
    Public Sub UpdateSalesOrder(ByVal currentSalesOrderHeader As SalesOrderHeader)
        Dim originalOrder As SalesOrderHeader = Me.ChangeSet.GetOriginal(currentSalesOrderHeader)

        If (currentSalesOrderHeader.EntityState = EntityState.Detached) Then
            If (IsNothing(originalOrder)) Then
                Me.ObjectContext.Attach(currentSalesOrderHeader)
            Else
                Me.ObjectContext.AttachAsModified(currentSalesOrderHeader, Me.ChangeSet.GetOriginal(currentSalesOrderHeader))
            End If
        End If

        For Each detail As SalesOrderDetail In Me.ChangeSet.GetAssociatedChanges(currentSalesOrderHeader, Function(o) o.SalesOrderDetails)
            Dim op As ChangeOperation = Me.ChangeSet.GetChangeOperation(detail)

            Select Case op
                Case ChangeOperation.Insert
                    If ((detail.EntityState = EntityState.Added) _
                    = False) Then
                        If ((detail.EntityState = EntityState.Detached) _
                                    = False) Then
                            Me.ObjectContext.ObjectStateManager.ChangeObjectState(detail, EntityState.Added)
                        Else
                            Me.ObjectContext.AddToSalesOrderDetails(detail)
                        End If
                    End If
                Case ChangeOperation.Update
                    Me.ObjectContext.AttachAsModified(detail, Me.ChangeSet.GetOriginal(detail))
                Case ChangeOperation.Delete
                    If (detail.EntityState = EntityState.Detached) Then
                        Me.ObjectContext.Attach(detail)
                    End If
                    Me.ObjectContext.DeleteObject(detail)
            End Select
        Next
    End Sub
    
    Public Sub DeleteSalesOrder(ByVal salesOrderHeader As SalesOrderHeader)
        If (salesOrderHeader.EntityState = EntityState.Detached) Then
            Me.ObjectContext.Attach(salesOrderHeader)
        End If

        Select Case salesOrderHeader.Status
            Case 1 ' in process
                Me.ObjectContext.DeleteObject(salesOrderHeader)
            Case 2, 3, 4 ' approved, backordered, rejected
                salesOrderHeader.Status = 6
            Case 5 ' shipped
                Throw New ValidationException("The order has been shipped and cannot be deleted.")
        End Select

    End Sub
End Class

[EnableClientAccess()]
public class OrderDomainService : LinqToEntitiesDomainService<AdventureWorksLT_DataEntities>
{
    public IQueryable<SalesOrderHeader> GetSalesOrders()
    {
        return this.ObjectContext.SalesOrderHeaders.Include("SalesOrderDetails");
    }

    public void UpdateSalesOrder(SalesOrderHeader currentSalesOrderHeader)
    {
        SalesOrderHeader originalOrder = this.ChangeSet.GetOriginal(currentSalesOrderHeader);

        if ((currentSalesOrderHeader.EntityState == EntityState.Detached))
        {
            if (originalOrder != null)
            {
                this.ObjectContext.AttachAsModified(currentSalesOrderHeader, this.ChangeSet.GetOriginal(currentSalesOrderHeader));
            }
            else
            {
                this.ObjectContext.Attach(currentSalesOrderHeader);
            }
        }

        foreach (SalesOrderDetail detail in this.ChangeSet.GetAssociatedChanges(currentSalesOrderHeader, o => o.SalesOrderDetails))
        {
            ChangeOperation op = this.ChangeSet.GetChangeOperation(detail);
            switch (op)
            {
                case ChangeOperation.Insert:
                    if ((detail.EntityState != EntityState.Added))
                    {
                        if ((detail.EntityState != EntityState.Detached))
                        {
                            this.ObjectContext.ObjectStateManager.ChangeObjectState(detail, EntityState.Added);
                        }
                        else
                        {
                            this.ObjectContext.AddToSalesOrderDetails(detail);
                        }
                    }
                    break;
                case ChangeOperation.Update:
                    this.ObjectContext.AttachAsModified(detail, this.ChangeSet.GetOriginal(detail));
                    break;
                case ChangeOperation.Delete:
                    if (detail.EntityState == EntityState.Detached)
                    {
                        this.ObjectContext.Attach(detail);
                    }
                    this.ObjectContext.DeleteObject(detail);
                    break;
                case ChangeOperation.None:
                    break;
                default:
                    break;
            }
        }
    }

    public void DeleteSalesOrder(SalesOrderHeader salesOrderHeader)
    {
        if ((salesOrderHeader.EntityState == EntityState.Detached))
        {
            this.ObjectContext.Attach(salesOrderHeader);
        }
        
        switch (salesOrderHeader.Status)
        {
            case 1: // in process
                this.ObjectContext.DeleteObject(salesOrderHeader);
                break;
            case 2: // approved
            case 3: // backordered
            case 4: // rejected
                salesOrderHeader.Status = 6;
                break;
            case 5: // shipped
                throw new ValidationException("The order has been shipped and cannot be deleted.");
            default:
                break;
        }
       
    }
}

备注

请创建在公开 LINQ to Entities 类型时派生自 LinqToEntitiesDomainService 类的域服务类。使用**“添加新域服务类”对话框创建公开 LINQ to Entities 类型的域服务时，该对话框将会自动创建派生自 LinqToEntitiesDomainService 的类。该类是通过为应用程序中业务逻辑的实现提供起点的方法创建的。该类中包含查询方法。如果选中“启用编辑”**复选框，则插入、更新和删除方法也将包括在内。您应该添加其他方法或自定义现有方法，从而满足自己的应用程序的要求。

使用 ObjectContext 属性可以访问用于简化与实体数据对象之间的交互的对象。

继承层次结构

System.Object
System.ServiceModel.DomainServices.Server.DomainService
System.ServiceModel.DomainServices.EntityFramework.LinqToEntitiesDomainService

线程安全

此类型的任何公共静态（在 Visual Basic 中为共享）成员都是线程安全的。不保证所有实例成员都是线程安全的。

平台

开发平台

Windows XP Home Edition, Windows XP Professional, Windows Server 2003 、Windows Server 2008 和 Windows 2000

目标平台

Change History

另请参见

参考

LinqToEntitiesDomainService 成员
 System.ServiceModel.DomainServices.EntityFramework 命名空间

通过