How to submit a file to an ASP.NET Core application

Question

I have an ASP.NET application that presents a simple form to upload files (images). That looks like this:

public IActionResult Process()
{
    return View();
}

[HttpPost]
public IActionResult Process(List files)
{
    var telemetry = new TelemetryClient();
    try
    {
        var result = files.Count + " file(s) processed " + Environment.NewLine;
        foreach (var file in files)
        {
            result += file.FileName + Environment.NewLine;
            var memoryStream = new MemoryStream();
            file.CopyTo(memoryStream);
            memoryStream.Seek(0, SeekOrigin.Begin);
            var binaryReader = new BinaryReader(memoryStream);
            var bytes = binaryReader.ReadBytes((int)memoryStream.Length);

            var imageInformation = ImageService.ProcessImage(bytes);

            ImageService.SaveImage(imageInformation.Result, bytes, file.FileName.Substring(file.FileName.LastIndexOf(".", StringComparison.Ordinal) + 1));
        }

        return View((object)result);
    }
    catch (Exception ex)
    {
        telemetry.TrackException(ex);
        throw;
    }
}

This form in the application works fine. The problem is that I want to use Microsoft Flow to submit files that come into a SharePoint library over to the web application defined above.

I have the file flow setup and it runs and doesn't error out, but when I look at the body of the HTTP action's result it says 0 files processed and nothing gets done.

The Flow that I have setup is

When a file is created (SharePoint) (this is pointing to a specific document library
Http (Http), Method: Post, Uri (pointing to my app), Body: File Content from the SharePoint step above.

As I mentioned this is posting to the site, but must not be passing in the file in a way that the ASP.NET method can handle, so it is not processing anything. How can I change either the flow or the Post method, so that it will work.

Updated with new information I have tried this with a very small image, so I can get some additional Request information. Using the form in the browser I tried this and going the following Request Raw result using Fiddler:

POST https://os-gbsphotoretain.azurewebsites.net/Image/Process HTTP/1.1
Host: os-gbsphotoretain.azurewebsites.net
Connection: keep-alive
Content-Length: 924
Pragma: no-cache
Cache-Control: no-cache
Origin: https://os-gbsphotoretain.azurewebsites.net
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.90 Safari/537.36
Content-Type: multipart/form-data; boundary=----WebKitFormBoundarySjQVgrsvAqJYXmST
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8
Referer: https://os-gbsphotoretain.azurewebsites.net/Image/Process
Accept-Encoding: gzip, deflate, br
Accept-Language: en-US,en;q=0.8
Cookie: _ga=GA1.3.955734319.1501514097; ai_user=UkqSf|2017-07-31T15:17:38.409Z; ARRAffinity=1628d46398b292eb2e3ba76b4b0f1eb1e30abd9bd1036d7a90b9c51f7baa2306; ai_session=/fPFh|1502738361594.15|1502738361594.15

------WebKitFormBoundarySjQVgrsvAqJYXmST
Content-Disposition: form-data; name="files"; filename="printer.jpg"
Content-Type: image/jpeg

     JFIF  ` `     C            



 $.' ",#(7),01444'9=82<.342   C         


2!!22222222222222222222222222222222222222222222222222     "                 

       } !1AQa "q2   #B  R  $3br    
%&'()*456789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz                                                                                       

       w !1AQ aq"2 B        #3R br 
$4 % &'()*56789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz                                                                             ?  
    +X K     21 c Z  ] ӥg v  ; :          P     I f >   m;] ֬u nm   ` Q 1 P6 s 9 |b r|   G  
------WebKitFormBoundarySjQVgrsvAqJYXmST--

Doing the same image through flow I get the following as the body in flow:

{
  "$content-type": "image/jpeg",
  "$content": "/9j/4AAQSkZJRgABAQEAYABgAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/2wBDAQkJCQwLDBgNDRgyIRwhMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjL/wAARCAAQABADASIAAhEBAxEB/8QAHwAAAQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQRBRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RFRkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ipqrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/8QAHwEAAwEBAQEBAQEBAQAAAAAAAAECAwQFBgcICQoL/8QAtREAAgECBAQDBAcFBAQAAQJ3AAECAxEEBSExBhJBUQdhcRMiMoEIFEKRobHBCSMzUvAVYnLRChYkNOEl8RcYGRomJygpKjU2Nzg5OkNERUZHSElKU1RVVldYWVpjZGVmZ2hpanN0dXZ3eHl6goOEhYaHiImKkpOUlZaXmJmaoqOkpaanqKmqsrO0tba3uLm6wsPExcbHyMnK0tPU1dbX2Nna4uPk5ebn6Onq8vP09fb3+Pn6/9oADAMBAAIRAxEAPwD1C9EMuqzGK1juS+3P7rccgc4yMYxjv1q/ol0I4bfTpQVniXaoyDuQHjoTg7ccGsDU7O+0+xEdoJfMUKiKE84MB/dJ5B9mzj6VneFtO1271qx1G+hubaGBjmCSUfMSMZZQNoxzgDnPfGKqcnypEJW1R//Z"
}

So it looks like flow is submitting as JSON. I'm going to try some additional processing now as a test, but if anybody knows what I can put in the Web app to handle this I would greatly appreciate it.

I added a new method see below that works when I run it locally passing in the string that Flow says is the body. But when I run it from flow I get value cannot be null error in the DeserializeObject line. How can I get the information that Flow is passing in.

[HttpPost]
    public IActionResult ProcessJson(string json)
    {
        var telemetry = new TelemetryClient();
        try
        {
            var result = "JSON processed " + Environment.NewLine;
            var details = (dynamic)Newtonsoft.Json.JsonConvert.DeserializeObject(json);
            var content = (string) details["$content"];
            var bytes = Convert.FromBase64String(content);

            ProcessBytes(bytes, "jpeg");
            return View("Process", result);
        }
        catch (Exception ex)
        {
            telemetry.TrackException(ex);
            throw;
        }
    }

I have also tried a method with this signature, but no luck there either it comes in as null

        [HttpPost]
        public IActionResult ProcessJson([FromBody]FlowFile file)
        {
...
        }



 public class FlowFile
    {

        [JsonProperty(PropertyName = "$content-type")]
        public string ContentType { get; set; }
        [JsonProperty(PropertyName = "$content")]
        public string Content { get; set; }
    }

I added some middleware, so that I could get the raw Request.Body and the end result that comes from that is this. I'm not sure what this equates to.


�����JFIF��`�`�����C�		
 $.' ",#(7),01444'9=82<.342���C			2!!22222222222222222222222222222222222222222222222222�����"��������������	
�������}�!1AQa"q2���#B��R��$3br�	
%&'()*456789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz�����������������������������������������������������������������������������������	
������w�!1AQaq"2�B����	#3R�br�
$4�%�&'()*56789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz�����������������������������������������������������������������������������?������+X�K�����21�c�Z��]�ӥg�v��;�:����������P����I�f�>���m;]�֬u�nm���`�Q�1�P6�s�9�|b�r|���G�

How to submit a file to an ASP.NET Core application

3 Answers