BeginExecuteCountQuery Method (AsyncDataSourceProvider)

Begins the asynchronous operation of querying the underlying data source for its count.

Syntax

Visual Basic
C#

'Declaration
 
Protected MustOverride Function BeginExecuteCountQuery( _
   ByVal queryParameters As CountQueryParameters, _
   ByVal callback As AsyncCallback, _
   ByVal state As Object _
) As IAsyncResult

'Usage
 
Dim instance As AsyncDataSourceProvider
Dim queryParameters As CountQueryParameters
Dim callback As AsyncCallback
Dim state As Object
Dim value As IAsyncResult
 
value = instance.BeginExecuteCountQuery(queryParameters, callback, state)

protected abstract IAsyncResult BeginExecuteCountQuery( 
   CountQueryParameters queryParameters,
   AsyncCallback callback,
   object state
)

Parameters

queryParameters: A CountQueryParameters that contains information about the operations that must be executed by the query on the underlying data source.
callback: The AsyncCallback delegate to be called when the operation is complete.
state: An object containing state information for the operation.

Return Value

An IAsyncResult representing the result of the operation.

Remarks

This method will only be called if CanCount is true. If the count is not known, CanCount should be set to false rather than returning a a null reference (Nothing in Visual Basic) or invalid value.

Requirements

Target Platforms: Windows 7, Windows Vista, Windows XP SP3, Windows Server 2008 family

Reference

AsyncDataSourceProvider Class
AsyncDataSourceProvider Members