`BlobLeaseClient` is missing a `GetUrl` getter

[felipecrv]

Is your feature request related to a problem? Please describe.

I need to know the URL of the BlobLeaseClient to produce good error message from my utility functions.

For convenience, a direct link to the header: https://github.com/Azure/azure-sdk-for-cpp/blob/main/sdk/storage/azure-storage-blobs/inc/azure/storage/blobs/blob_lease_client.hpp

Describe the solution you'd like

BlobLeaseClient should have a GetUrl getter.

blob_lease_client.hpp:

  std::string BlobLeaseClient::GetUrl() const
  {
    if (m_blobClient.HasValue())
    {
      return m_blobClient->GetUrl();
    }
    else if (m_blobContainerClient.HasValue())
    {
      return m_blobContainerClient->GetUrl();
    }
    else
    {
      AZURE_UNREACHABLE_CODE();
    }
  }

blob_lease_client.cpp:

    /**
     * @brief Get's the primary URL endpoint of the blob or container.
     *
     * @return A URL of a blob or container.
     */
    std::string GetUrl() const;

Describe alternatives you've considered

Passing a string as parameter everywhere in my code.

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[Jinming-Hu]

Lease client is a convenient method for customers to do lease operations, unlike BlobClient, BlobContainerClient or BlobServiceClient, lease client doesn't have a corresponding real resource at server side. I think maybe we shouldn't have GetUrl for it.

@LarryOsterman What do you think?

[LarryOsterman]

The C++ guidelines require that service clients support a GetUrl method. The same does not apply to non-service clients.

How is a LeaseClient instantiated? With a connection string/url? Or is it instantiated with a BlobClient? Or from a BlobClient?

If it's constructed with a connection string or URL it makes sense for there to be a GetUrl method.
If it's constructed from or with a BlobClient, it doesn't make sense for there to be a GetUrl method.

One thing you might consider is having an ostream inserter for LeaseClient which generates a meaningful string for diagnostics. That would resolve the customer concern without having to add a method which doesn't necessarily make sense. You can think of an ostream inserter as being logically similar to the C# "ToString()" method.

[felipecrv]

At the moment I can't generate a meaningful string through the the public interface of BlobLeaseClient because there isn't a single public member function that can tell me anything about the resource the BlobLeaseClient targets.

GetUrl might be a bad name for it, but I believe there should be a way to ask for a string that identifies the resource receiving the lease operations that BlobLeaseClient can trigger.

[felipecrv]

These are the private data members of BlobLeaseClient

  private:
    Azure::Nullable<BlobClient> m_blobClient;
    Azure::Nullable<BlobContainerClient> m_blobContainerClient;
    std::mutex m_mutex;
    std::string m_leaseId;

It can be instantiated by passing either BlobClient or BlobContainerClient because blobs and containers can be leased. Once you give a client to the BlobLeaseClient you can never recover information about them anymore, you would have to keep a copy of the client and not loose track of the client/lease-client pairing.

[RickWinter]

@Jinming-Hu We should expose at a minimum the LeaseId. I'm mixed on whether it makes sense to expose the URL of the targeted object. Other language SDKs do expose both of these values.
see: https://learn.microsoft.com/en-us/dotnet/api/azure.storage.blobs.specialized.blobleaseclient?view=azure-dotnet