LoadOperation Class

Artigo
01/27/2012

[WCF RIA Services Version 1 Service Pack 2 is compatible with either .NET framework 4 or .NET Framework 4.5, and with either Silverlight 4 or Silverlight 5.]

Represents an asynchronous load operation.

Inheritance Hierarchy

System.Object
  System.ServiceModel.DomainServices.Client.OperationBase
    System.ServiceModel.DomainServices.Client.LoadOperation
      System.ServiceModel.DomainServices.Client.LoadOperation<TEntity>

Namespace: System.ServiceModel.DomainServices.Client
Assembly: System.ServiceModel.DomainServices.Client (in System.ServiceModel.DomainServices.Client.dll)

Syntax

'Declaration
Public MustInherit Class LoadOperation _
    Inherits OperationBase

'Usage
Dim instance As LoadOperation

public abstract class LoadOperation : OperationBase

public ref class LoadOperation abstract : public OperationBase

[<AbstractClassAttribute>]
type LoadOperation =  
    class
        inherit OperationBase
    end

public abstract class LoadOperation extends OperationBase

The LoadOperation type exposes the following members.

Properties

	Name	Description
	AllEntities	Gets all the entities loaded by the operation, including any entities referenced by the top-level entities.
	CanCancel	Gets a value that indicates whether this OperationBase is currently in a state that enables it to be canceled. (Inherited from OperationBase.)
	Entities	Gets all the top-level entities loaded by the operation.
	EntityQuery	Gets the System.ServiceModel.DomainServices.Client.EntityQuery for this load operation.
	Error	Gets the operation error if the operation failed. (Inherited from OperationBase.)
	HasError	Gets a value that indicates whether the operation failed. (Inherited from OperationBase.)
	IsCanceled	Gets a value that indicates whether this operation has been canceled. (Inherited from OperationBase.)
	IsComplete	Gets a value that indicates whether this operation has completed. (Inherited from OperationBase.)
	IsErrorHandled	Gets or sets a value that indicates whether the operation error has been handled. (Inherited from OperationBase.)
	LoadBehavior	Gets the System.ServiceModel.DomainServices.Client.LoadBehavior for this load operation.
	Result	Gets the DomainClientResult for this operation.
	SupportsCancellation	Gets a value that indicates whether this operation supports cancellation. (Inherited from OperationBase.)
	TotalEntityCount	Gets the total server entity count for the query used by this operation.
	UserState	Gets the optional user state for this operation. (Inherited from OperationBase.)
	ValidationErrors	Gets the validation errors.

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Methods

	Name	Description
	Cancel	Cancels the operation. (Inherited from OperationBase.)
	CancelCore	When overridden in a derived class, provides the logic to cancel the operation. (Inherited from OperationBase.)
	Complete(Exception)	Completes a failed operation with the specified error. (Inherited from OperationBase.)
	Complete(Object)	Completes a successful operation with the specified result. (Inherited from OperationBase.)
	Equals	(Inherited from Object.)
	Finalize	(Inherited from Object.)
	GetHashCode	(Inherited from Object.)
	GetType	(Inherited from Object.)
	InvokeCompleteAction	Invokes the completion callback. (Inherited from OperationBase.)
	MarkErrorAsHandled	Specifies that an error encountered in an operation is handled. (Inherited from OperationBase.)
	MemberwiseClone	(Inherited from Object.)
	OnPropertyChanged	Called when the value of a property changes. (Inherited from OperationBase.)
	RaisePropertyChanged	Raises the System#ComponentModel#INotifyPropertyChanged#PropertyChanged() event. (Inherited from OperationBase.)
	ToString	(Inherited from Object.)
	UpdateResults	Updates the observable result collections.

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Events

	Name	Description
	Completed	Occurs when the operation completes. (Inherited from OperationBase.)

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Explicit Interface Implementations

	Name	Description
	INotifyPropertyChanged.PropertyChanged	Occurs when a property value changes. (Inherited from OperationBase.)

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Examples

' Create an EntityQuery of type Customer
Dim query As EntityQuery(Of Customer) = _
    From c In _customerContext.GetCustomersQuery() _
    Where (c.Phone.StartsWith("583")())() _
    Order By (c.LastName) _
    Select c()

' Create and execute a LoadOperation of type Customer and load 'query'
Dim loadOp As LoadOperation = Me._customerContext.Load(query)

' Create a new DomainOperationException for a Validation Error
Dim opEx As DomainOperationException = New DomainOperationException( _
                                        "Validation Error", _
                                        OperationErrorStatus.ValidationError, _
                                        9466)
' Check if there are any ValidationErrors when loadOp was executed
' Then throw the DomainOperationException opEx
If loadOp.ValidationErrors <> Empty Then
    Throw opEx
End If

' Populate the CustomerGrid with the Entities in loadOp
CustomerGrid.ItemsSource = loadOp.Entities

// Create an EntityQuery of type Customer
EntityQuery<Customer> query =
    from c in _customerContext.GetCustomersQuery()
    where c.Phone.StartsWith("583")
    orderby c.LastName
    select c;

// Create and execute a LoadOperation of type Customer and load 'query'
LoadOperation<Customer> loadOp = this._customerContext.Load(query);

// Create a new DomainOperationException for a Validation Error
DomainOperationException opEx = new DomainOperationException(
    "Validation Error",
    OperationErrorStatus.ValidationFailed,
    0x000024FA);

// Check if there are any ValidationErrors when loadOp was executed
// Then throw the DomainOperationException opEx
if (loadOp.ValidationErrors != null)
{
    throw opEx;
}

// Populate the CustomerGrid with the Entities in loadOp
CustomerGrid.ItemsSource = loadOp.Entities;

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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