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CloudBlobContainer.BeginFetchAttributes Method (BlobRequestOptions, AsyncCallback, Object)

Updated: April 24, 2013

[This topic is part of the Windows Azure Storage Client Library 1.7, which has been deprecated. The current recommended version is Storage Client Library 3.0.]

Begins an asynchronous operation to retrieve the container's attributes, using a conditional request based on the BlobRequestOptions that you specify.

Namespace: Microsoft.WindowsAzure.StorageClient
Assembly: Microsoft.WindowsAzure.StorageClient (in Microsoft.WindowsAzure.StorageClient.dll)

'Usage

public IAsyncResult BeginFetchAttributes (
	BlobRequestOptions options,
	AsyncCallback callback,
	Object state
)

Parameters

options

Type: Microsoft.WindowsAzure.StorageClient.BlobRequestOptions

An object that specifies any additional options for the request.

callback

Type: System.AsyncCallback

The callback delegate that will receive notification when the asynchronous operation completes.

state

Type: System.Object

A user-defined object that will be passed to the callback delegate.

Return Value

Type: System.IAsyncResult

An IAsyncResult that references the asynchronous operation.

The following code example retrieves a container's attributes and writes out its properties and metadata.

static void FetchContainerAttributesAsync(Uri blobEndpoint, string accountName, string accountKey)
{
    //Create service client for credentialed access to the Blob service.
    CloudBlobClient blobClient = 
        new CloudBlobClient(blobEndpoint, new StorageCredentialsAccountAndKey(accountName, accountKey));

    //Get a reference to a container.
    CloudBlobContainer container = blobClient.GetContainerReference("mycontainer");

    //Populate the container's properties and metadata.
    container.BeginFetchAttributes(FetchContainerAttributesCallback, container);
}

static void FetchContainerAttributesCallback(IAsyncResult result)
{
    CloudBlobContainer container = (CloudBlobContainer)result.AsyncState;

    //Handle the exception in case the container does not exist.
    try
    {
        //End the operation.
        container.EndFetchAttributes(result);

        //List some container properties.
        Console.WriteLine("Container: " + container.Name);
        Console.WriteLine();

        Console.WriteLine("Container properties:");
        Console.WriteLine("\tLastModifiedUTC: " + container.Attributes.Properties.LastModifiedUtc);
        Console.WriteLine("\tETag: " + container.Attributes.Properties.ETag);
        Console.WriteLine();

        //Enumerate the container's metadata.
        foreach (var metadataKey in container.Metadata.Keys)
        {
            Console.WriteLine("Metadata name: " + metadataKey.ToString());
            Console.WriteLine("Metadata value: " + container.Metadata.Get(metadataKey.ToString()));
        }
    }
    catch (StorageClientException e)
    {
        if (e.ErrorCode == StorageErrorCode.ResourceNotFound)
        {
            Console.WriteLine("Container does not exist.");
        }
        else
        {
            Console.WriteLine(e.ErrorCode);
        }
    }
}

The BeginFetchAttributes method begins an operation to populate the container's system properties and user-defined metadata. Before reading a container's properties or metadata, you should always call this method or the FetchAttributes method to retrieve the latest values for the container's properties and metadata from the service.


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

Development Platforms

Windows Vista, Windows 7 and Windows Server 2008

Target Platforms

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