I am in the process of creating a proxy server that makes a request to a PDF Blob link then takes the request to setup its HttpResponse Header which we sent to the client. This diagram should explain

As of now, I am successful at making the request to get the pdf content however I am not sure how to send that back to the user. I have followed other Stackoverflow post such as this one :

What I am actually returning to the client

Here is the code I am using to create this proxy endpoint

        [AllowAnonymous]
        [HttpGet("openPDF")]
        public async Task<HttpResponseMessage> OpenPDF([FromQuery] string url)
        {
            var _httpClient = _httpClientFactory.CreateClient();
            var response = await _httpClient.GetAsync(url);
            var stream = await response.Content.ReadAsStreamAsync();

            HttpResponseMessage message = new HttpResponseMessage(HttpStatusCode.OK);
            message.Content = new StreamContent(stream);
            message.Content.Headers.ContentLength = stream.Length;
            message.Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");

            return message;
        }

EDIT

Ok so this actually sends back the PDF when I write the proxy like this

        [AllowAnonymous]
        [HttpGet("openPDF")]
        public async Task<FileStreamResult> OpenPDF([FromQuery] string url)
        {
            var fileStream = new MemoryStream();

            var _httpClient = _httpClientFactory.CreateClient();

            var file = await _httpClient.GetStreamAsync(url).ConfigureAwait(false);
            await file.CopyToAsync(fileStream);

            fileStream.Position = 0;
            
            return File(fileStream, "application/pdf", "filename.pdf");
        }

The problem is I want to update the content-disposition to inline so I can force this to open in the browser instead of downloading.So I decided to take the filestream and injecting that in the httpResponseMessage.content instead but that still didn't work. It would continue to send me a json file

        [AllowAnonymous]
        [HttpGet("openPDF")]
        public async Task<HttpResponseMessage> OpenPDF([FromQuery] string url)
        {
            var fileStream = new MemoryStream();

            var _httpClient = _httpClientFactory.CreateClient();

            var file = await _httpClient.GetStreamAsync(url).ConfigureAwait(false);
            await file.CopyToAsync(fileStream);

            fileStream.Position = 0;
            

            HttpResponseMessage message = new HttpResponseMessage(HttpStatusCode.OK);
            message.Content = new StreamContent(fileStream);
            message.Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");

            return message;
        }

To be honest, I thought defining the content-type should suffice but guess not

CodePudding user response：

This is pretty straight forward for .NET 6... suspect it should be roughly the same for .NET 4x... This uses the NuGet package Azure.Storage.Blobs

https://github.com/Azure/azure-sdk-for-net/blob/Azure.Storage.Blobs_12.13.1/sdk/storage/Azure.Storage.Blobs/README.md

[HttpGet("stream")]
public async Task GetBlobAsync()
{
    var url = new Uri("https://path.to.blob.content/xxx");
    var blobClient = new BlobClient(url);
    Response.Headers.Add("Content-Type", "application/pdf");
    Response.Headers.Add("Content-Disposition", @"attachment;filename=""intended file name.pdf""");
    await blobClient.DownloadToAsync(Response.Body);

}