| CloudBlobDirectory.BeginListBlobsSegmented Method (Int32, ResultContinuation, BlobRequestOptions, AsyncCallback, Object) |
| See Also Example |
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Begins an asynchronous request to return a result segment containing a collection of blob items, using a conditional request based on the BlobRequestOptions that you specify. Use this overload when you want to control the maximum number of results returned at a time, and when you want to use a continuation token to determine whether there are more results to return from the service after the current page completes. Namespace: Microsoft.WindowsAzure.StorageClient
Assembly: Microsoft.WindowsAzure.StorageClient (in Microsoft.WindowsAzure.StorageClient.dll)
Usage
| Visual Basic |
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Dim instance As CloudBlobDirectory Dim maxResults As Integer Dim continuationToken As ResultContinuation Dim options As BlobRequestOptions Dim callback As AsyncCallback Dim state As Object Dim returnValue As IAsyncResult returnValue = instance.BeginListBlobsSegmented(maxResults, continuationToken, options, callback, state) |
Syntax
| Visual Basic |
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Public Function BeginListBlobsSegmented ( _ maxResults As Integer, _ continuationToken As ResultContinuation, _ options As BlobRequestOptions, _ callback As AsyncCallback, _ state As Object _ ) As IAsyncResult |
| C# |
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public IAsyncResult BeginListBlobsSegmented ( int maxResults, ResultContinuation continuationToken, BlobRequestOptions options, AsyncCallback callback, Object state ) |
| C++ |
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public: IAsyncResult^ BeginListBlobsSegmented ( int maxResults, ResultContinuation^ continuationToken, BlobRequestOptions^ options, AsyncCallback^ callback, Object^ state ) |
| J# |
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| JScript |
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Parameters
- maxResults
A non-negative integer value that indicates the maximum number of results to be returned at a time, up to the per-operation limit of 5000. If this value is zero, the maximum possible number of results will be returned, up to 5000.
- continuationToken
A continuation token returned by a previous listing operation.
- options
An object that specifies any additional options for the request.
- callback
The callback delegate that will receive notification when the asynchronous operation completes.
- state
A user-defined object that will be passed to the callback delegate.
Return Value
An IAsyncResult that references the asynchronous operation.Example
The following code example lists the blobs in a blob directory in segments, using the default hierarchical listing.
| Copy Code | |
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static void ListBlobsInDirectoryAsynchronously(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 blob directory.
CloudBlobDirectory blobDir = blobClient.GetBlobDirectoryReference("myvirtualdir/a/");
//Begin the operation to return the first segment of blobs, passing the service client to the callback.
blobDir.BeginListBlobsSegmented(ListBlobsInDirectoryCallback, blobDir);
}
static void ListBlobsInDirectoryCallback(IAsyncResult result)
{
CloudBlobDirectory blobDir = (CloudBlobDirectory)result.AsyncState;
//End the operation.
ResultSegment<IListBlobItem> resultSegment = blobDir.EndListBlobsSegmented(result);
//Enumerate the blob items.
foreach (var blobItem in resultSegment.Results)
{
Console.WriteLine(blobItem.Uri);
}
//Check the continuation token to determine whether there are more results.
if (resultSegment.ContinuationToken != null)
{
//Get the next result segment, returning up to 1000 blobs per operation.
blobDir.BeginListBlobsSegmented(1000, resultSegment.ContinuationToken, new BlobRequestOptions(), ListBlobsInSegmentsCallback, blobDir);
}
}
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Remarks
The BeginListBlobsSegmented method begins an operation to list blobs in pages. To specify the page size to return, pass in a non-zero value for the maxResults parameter. Passing in zero for the maxResults parameter returns either the maximum number of results available, or the per-operation limit of 5000 results.
If you have specified a page size, you can check the HasMoreResults property to check whether the page is complete. For example, if you have specified a page size of 10,000, a value which exceeds the per-operation limit, HasMoreResults will return true, indicating that the page is not complete. Note that if you have not specified a page size, HasMoreResults will always be false.
If you have not specified a page size, or the value of maxResults is zero, then check the value of the ContinuationToken property to determine whether there are more results to return. The continuation token is non-null as long as there are more results to return from the service.
Call the GetNext method to return the next segment of results from the service.
The objects returned by the listing depend on the type of listing that is being performed. If the UseFlatBlobListing property is set to true, the listing will return an enumerable collection of CloudBlob objects. If UseFlatBlobListing is set to false (the default value), the listing may return a collection containing CloudBlob objects and CloudBlobDirectory objects. The latter case provides a convenience for subsequent enumerations over a virtual blob hierarchy.