How to handle Optimistic Concurrency in Azure.Storage.Blobs v12.x.x of Azure dll - azure

Question

I am trying to Implement the example shared in Learn Path
https://github.com/MicrosoftDocs/mslearn-support-concurrency-blob-storage/blob/master/src/OptimisticNewsEditor/Program.cs
I am trying to use the v12 dll which is Azure.Storage.Blobs
this is the code I have.
public static async Task Main()
{
BlobContainerClient container;
try
{
container = new BlobServiceClient(connectionString).GetBlobContainerClient(containerName);
await container.CreateIfNotExistsAsync(PublicAccessType.None);
}
catch (Exception)
{
var msg = $"Storage account not found. Ensure that the environment variable " +
" is set to a valid Azure Storage connection string and that the storage account exists.";
Console.WriteLine(msg);
return;
}
// First, the newsroom chief writes the story notes to the blob
await SimulateChief();
Console.WriteLine();
await Task.Delay(TimeSpan.FromSeconds(2));
// Next, two reporters begin work on the story at the same time, one starting soon after the other
var reporterA = SimulateReporter("Reporter A", writingTime: TimeSpan.FromSeconds(12));
await Task.Delay(TimeSpan.FromSeconds(4));
var reporterB = SimulateReporter("Reporter B", writingTime: TimeSpan.FromSeconds(4));
await Task.WhenAll(reporterA, reporterB);
await Task.Delay(TimeSpan.FromSeconds(2));
Console.WriteLine();
Console.WriteLine("=============================================");
Console.WriteLine();
Console.WriteLine("Reporters have finished, here's the story saved to the blob:");
BlobDownloadInfo story = await container.GetBlobClient(blobName).DownloadAsync();
Console.WriteLine(new StreamReader(story.Content).ReadToEnd());
}
private static async Task SimulateReporter(string authorName, TimeSpan writingTime)
{
// First, the reporter retrieves the current contents
Console.WriteLine($"{authorName} begins work");
var blob = new BlobContainerClient(connectionString, containerName).GetBlobClient(blobName);
var contents = await blob.DownloadAsync();
Console.WriteLine($"{authorName} loads the file and sees the following content: \"{new StreamReader(contents.Value.Content).ReadToEnd()}\"");
// Store the current ETag
var properties = await blob.GetPropertiesAsync();
var currentETag = properties.Value.ETag;
Console.WriteLine($"\"{contents}\" has this ETag: {properties.Value.ETag}");
// Next, the author writes their story. This takes some time.
Console.WriteLine($"{authorName} begins writing their story...");
await Task.Delay(writingTime);
Console.WriteLine($"{authorName} has finished writing their story");
try
{
// Finally, they save their story back to the blob.
var story = $"[[{authorName.ToUpperInvariant()}'S STORY]]";
await uploadDatatoBlob(blob, story);
Console.WriteLine($"{authorName} has saved their story to Blob storage. New blob contents: \"{story}\"");
}
catch (RequestFailedException e)
{
// Catch error if the ETag has changed it's value since opening the file
Console.WriteLine($"{authorName} sorry cannot save the file as server returned an error: {e.Message}");
}
}
private static async Task SimulateChief()
{
var blob = new BlobContainerClient(connectionString, containerName).GetBlobClient(blobName);
var notes = "[[CHIEF'S STORY NOTES]]";
await uploadDatatoBlob(blob, notes);
Console.WriteLine($"The newsroom chief has saved story notes to the blob {containerName}/{blobName}");
}
private static async Task uploadDatatoBlob(BlobClient blob, string notes)
{
byte[] byteArray = Encoding.UTF8.GetBytes(notes);
MemoryStream stream = new MemoryStream(byteArray);
await blob.UploadAsync(stream, overwrite: true);
}
I need to modify the UploadAsync to check for ETag before Uploading.
In the old version of Azure .Net CLI we had Microsoft.Azure.Storage.Blob dll now this handled Optimistic Concurrency by
await blob.UploadTextAsync(story, null, accessCondition: AccessCondition.GenerateIfMatchCondition(currentETag), null, null);
How do i do this in v12 dll.
Any Help appreciated.

Answer 1

Please use the following override of UploadAsync method:
UploadAsync(Stream, BlobHttpHeaders, IDictionary<String,String>, BlobRequestConditions, IProgress<Int64>, Nullable<AccessTier>, StorageTransferOptions, CancellationToken)
You can define the access conditions as part of BlobRequestConditions parameter.