CODEWITHSUNDEEP
azureasp.net-coreazure-storageazure-blob-storage
Mitch
Mitch

Reputation: 2551

How do you check that a container exists in Azure Blob Storage V12

Previously when using Azure Blob Storage SDK V11, if you wanted to Create a container but were unsure if the container existed you could use CreateIfNotExists.

However in version V12, CreateIfNotExists is no longer available and the only example I can find from Microsoft is to simply create a Container without checking if it already exists.

So, does anyone know the best practice in V12 to check if a container exists before trying to create it.

Incidentally, I'm developing for ASP.Net Core 3.1.

Upvotes: 29

Views: 38326

Answers (4)

Ivan Glasenberg
Ivan Glasenberg

Reputation: 29940

In v12, there are 2 ways to check if the container exists or not.

1.

BlobServiceClient blobServiceClient = new BlobServiceClient(connectionString);

//get a BlobContainerClient
var container = blobServiceClient.GetBlobContainerClient("the container name");
            
//you can check if the container exists or not, then determine to create it or not
bool isExist = container.Exists();
if (!isExist)
{
    container.Create();
}

//or you can directly use this method to create a container if it does not exist.
 container.CreateIfNotExists();

You can directly create a BlobContainerClient, then use code below:

//create a BlobContainerClient 
BlobContainerClient blobContainer = new BlobContainerClient("storage connection string", "the container name");
    
//use code below to check if the container exists, then determine to create it or not
bool isExists = blobContainer.Exists();
if (!isExist)
{
   blobContainer .Create();
}
    
//or use this code to create the container directly, if it does not exist.
blobContainer.CreateIfNotExists();

Upvotes: 53

gab
gab

Reputation: 335

I have the following method to get a SAS token, everything works fine.

private Uri GetUriSasToken()
    {
        string storedPolicyName = null;
        string connectionString = _config.GetConnectionString("BlobConnection");
        BlobContainerClient containerClient = new BlobContainerClient(connectionString, "stock");

        // Check whether this BlobContainerClient object has been authorized with Shared Key.
        if (containerClient.CanGenerateSasUri)
        {
            // Create a SAS token that's valid for one hour.
            BlobSasBuilder sasBuilder = new BlobSasBuilder()
            {
                BlobContainerName = containerClient.Name,
                Resource = "c"
            };

            if (storedPolicyName == null)
            {
                sasBuilder.ExpiresOn = DateTimeOffset.UtcNow.AddHours(1);
                sasBuilder.SetPermissions(BlobContainerSasPermissions.Read | BlobContainerSasPermissions.List);
            }
            else
            {
                sasBuilder.Identifier = storedPolicyName;
            }

            Uri sasUri = containerClient.GenerateSasUri(sasBuilder);
            return sasUri;
        }
        else
        {
            _logger.LogError(@"BlobContainerClient must be authorized with Shared Key credentials to create a service SAS.");
            return null;
        }
                 
    }

Then, I call the above method with the following code:

   BlobServiceClient blobServiceClient = new BlobServiceClient(GetUriSasToken(), null);
        var blobName = _config.GetValue<string>("BlobName");
        var containerName = _config.GetValue<string>("ContainerName");            
        var fileName = _config.GetValue<string>("FileName");            
        var containerClient = blobServiceClient.GetBlobContainerClient(containerName);

Is there any way I can verify that the container exists?

I'm not sure I can do:

containerClient.Exists

I used it but it returns an error that the Blob does not exists, but I want to check first if the container exists.

Anyone has done this?

Upvotes: -1

Mehmet Taha Meral
Mehmet Taha Meral

Reputation: 3843

The accepted answer is fine. But I usually use the async version of it.

var _blobServiceClient = new BlobServiceClient(YOURCONNECTIONSTRING);
var containerClient = _blobServiceClient.GetBlobContainerClient(YOURCONTAINERNAME);
await containerClient.CreateIfNotExistsAsync(Azure.Storage.Blobs.Models.PublicAccessType.BlobContainer);

The version I'm using is Azure.Storage.Blobs v12.4.1

Upvotes: 8

Gaurav Mantri
Gaurav Mantri

Reputation: 136126

However in version V12, CreateIfNotExists is no longer available and the only example I can find from Microsoft is to simply create a Container without checking if it already exists.

I am not sure why do you say CreateIfNotExists is no longer available in version 12 of storage client library. It is certainly there in BlobContainerClient class. Here's the direct link: CreateIfNotExists.

    var connectionString = "UseDevelopmentStorage=true";            
    var containerClient = new BlobContainerClient(connectionString, containerName);
    containerClient.CreateIfNotExists();

Upvotes: 2

Related Questions