Azure function - request image from 3d party then send image to requestor without saving to local directory - image

Question

I've found lots of questions about downloading images and as my code shows that is what I ended up doing. However that is not the behavior I want. I just want it to return the image directly.
using System.Net;
using Microsoft.Extensions.Logging;
using System.IO;
public static async Task<HttpResponseMessage> Run(HttpRequest req, ILogger log, string data)
{
log.LogInformation("start function...");
string qrData = $"{data}";//req.Query["id"];
string QrGeneratorUrl = "https://api.qrserver.com/v1/create-qr-code/?size=100x100&data="+ qrData;
log.LogInformation("QrUrl= " + QrGeneratorUrl);
var filename = "temp.png";
var filePath = Path.Combine(#"d:\home\site\wwwroot\QrGeneratorTest\"+filename);
WebClient myWebClient = new WebClient();
myWebClient.DownloadFile(QrGeneratorUrl, filePath);
var response = new HttpResponseMessage(HttpStatusCode.OK);
var fileStream = new FileStream(filePath, FileMode.Open);
response.Content = new StreamContent(fileStream);
return response;
}
I've tried converting the image to a byte stream and adding the stream to the response content, I've tried putting the image data directly as string content... nothing seems to work - it only transmits the image if it is a local file and I add it to the response via fileStream. Does someone know how I can get it to just put the response I get into the response I am returning? Or explain why it can't be done? This is functionality that exists in a web app that we are trying the move into a function and the web app is able to pass the content along without saving it. Using a byte stream. But I can't seem to replicate that in the function.
There are 2 reasons we are not calling qr server directly
1) it's a 3d party site so it could go down and we need to be able to swap it out for a new provider from one location.
2) we need to build the url so it has not parameters (?p=1&q=2&r=3...) as this is going into an email and having a bunch of parameters often tags the email as junk. With Azure (as with our web app) we can build the url like this: /getImage/1/2/3 which is less likely to be tagged as spam
any insight would be appreciated!!
//*******************//
ANSWER
here is my final code. I think the issue was Stream vs MemoryStream... In any case here is the full code:
#r "Newtonsoft.Json"
using System.Net;
using System;
using System.Web;
using System.Threading.Tasks;
using System.IO;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
public static async Task<HttpResponseMessage> Run(HttpRequest req, ILogger log, string data)
{
log.LogInformation("start function...");
string qrData = $"{data}";
//string qrData = DateTime.Now.Ticks.ToString();
string QrGeneratorUrl = "https://api.qrserver.com/v1/create-qr-code/?size=100x100&qzone=2&data="+ qrData;
//get the QR image from 3d party api
var httpWebRequest = WebRequest.Create(QrGeneratorUrl);
var httpResponse = await httpWebRequest.GetResponseAsync();
//put 3d party response into function response
Stream ms = httpResponse.GetResponseStream(); //new MemoryStream(bytes);
var result = new HttpResponseMessage(HttpStatusCode.OK);
result.Content = new StreamContent(ms);
result.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");
return result;
}

Answer 1

Suppose you want to download the image to stream and just return it(If use browser send the request, show the image in the browser, If I get it wrong please let me know). If this is your purpose you could refer to my below code, I download the image from blob and return it to FileContentResult.
using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Blob;
using System.DrawingCore;
namespace FunctionApp72
{
public static class Function1
{
[FunctionName("Function1")]
public static async Task<IActionResult> RunAsync(
[HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
ILogger log)
{
log.LogInformation("C# HTTP trigger function processed a request.");
CloudStorageAccount blobAccount = CloudStorageAccount.Parse(Environment.GetEnvironmentVariable("AzureWebJobsStorage"));
CloudBlobClient blobClient = blobAccount.CreateCloudBlobClient();
CloudBlobContainer blobContainer = blobClient.GetContainerReference("test");
CloudBlockBlob cloudBlockBlob = blobContainer.GetBlockBlobReference("test.jpg");
MemoryStream streamIn = new MemoryStream();
await cloudBlockBlob.DownloadToStreamAsync(streamIn);
Image originalImage = Bitmap.FromStream(streamIn);
return new FileContentResult(ImageToByteArray(originalImage), "image/jpeg");
}
private static byte[] ImageToByteArray(Image image)
{
ImageConverter converter = new ImageConverter();
return (byte[])converter.ConvertTo(image, typeof(byte[]));
}
}
}
And I deploy it to azure It still could return the image.