试图从 azure blob 下载 word 文档

Question

i am trying to download the word document stored in azure blob container having private access and i need to convert downloaded document into byte array so that i can be able to send to react app

this is the code i am trying below

    [Authorize, HttpGet("{id}/{projectphase?}")]
    public async Task<ActionResult<DesignProject>> GetDesignProject(string id, string projectphase = null)
    {
          var blobContainerName = Startup.Configuration["AzureStorage:BlobContainerName"];
          var azureStorageConnectionString = Startup.Configuration["AzureStorage:ConnectionString"];

          BlobContainerClient blobContainerClient = new BlobContainerClient(azureStorageConnectionString, blobContainerName);
          blobContainerClient.CreateIfNotExists();
          .......  // not sure how to proceed further 
          .......
          ......
          return new InlineFileContentResult('here i need to return byte array???', "application/docx") { FileDownloadName = fileName };
    }

I have got the full path name where the file has been stored like as below

https://xxxx.blob.core.windows.net/design-project-files/99999-99/99999-99-BOD-Concept.docx

and then i have got the file name as well 99999-99-BOD-Concept.docx

Could any one please guide me how to proceed with the next to download the document that would be very grateful to me.

Answer 1

Please try something like the following (untested code though):

public async Task<ActionResult<DesignProject>> GetDesignProject(string id, string projectphase = null)
{
      var blobContainerName = Startup.Configuration["AzureStorage:BlobContainerName"];
      var azureStorageConnectionString = Startup.Configuration["AzureStorage:ConnectionString"];

      BlobContainerClient blobContainerClient = new BlobContainerClient(azureStorageConnectionString, blobContainerName);
      blobContainerClient.CreateIfNotExists();
      var blobClient = new BlobClient("https://xxxx.blob.core.windows.net/design-project-files/99999-99/99999-99-BOD-Concept.docx");
      var blobName = blobClient.Name;
      blobClient = new BlobClient(azureStorageConnectionString, blobContainerName, blobName);
      using (var ms = new MemoryStream())
      {
        await blobClient.DownloadToAsync(ms);
        return new InlineFileContentResult(ms.ToArray(), "application/docx") { FileDownloadName = fileName };
      }
}

Basically what we're doing is that we're first creating a BlobClient using the URL that you have so that we can extract blob's name out of that URL (you can do URL parsing as well). Once we have the blob's name, we create a new instance of BlobClient using connection string, blob container name and blob's name.

Then we download the blob's content as stream and convert that stream to byte array (this part I am not 100% sure that my code would work) and return that byte array.

Answer 2

You don't really need to have this process where your react app requests to your server, so your server downloads the file and then sends it to the react app; that file in blob storage is on the web, downloadable from blob storage so it's kinda unnecessary to hassle your sevrer into being a proxy for it

If you configure public access for blobs then you just put that URL into your react app - user clicks it, bytes download. Happy days. If you have a private container you can still generate SAS URLs for the blobs

If you actually need the bytes in your react app, then just fetch it with a javascript web request - you'll need to set a CORS policy on the blob container though

---

If you really want to download the file to/via the server, you'll probably have to get into streaming it to the response stream connected to the react app, passed into the SOMETHING below:

        BlobClient blob = blobContainerClient.GetBlobClient( BLOB NAME I.E PATH INSIDE CONTAINER);

        //download to a file or stream
        await blob.DownloadToAsync( SOMETHING );