Uploading an image using C# and WebRequest?

Question

Here is the working code in Python (using cURL):

#!/usr/bin/python

import pycurl

c = pycurl.Curl()
values = [
          ("key", "YOUR_API_KEY"),
          ("image", (c.FORM_FILE, "file.png"))]
# OR:     ("image", "http://example.com/example.jpg"))]
# OR:     ("image", "BASE64_ENCODED_STRING"))]

c.setopt(c.URL, "http://imgur.com/api/upload.xml")
c.setopt(c.HTTPPOST, values)

c.perform()
c.close()

Here's what I have in C#:

public void UploadImage()
    {
        //I think this line is doing something wrong.
        //byte[] x = File.ReadAllBytes(@"C:\Users\Sergio\documents\visual studio 2010\Projects\WpfApplication1\WpfApplication1\Test\hotness2.jpg");

        //If I do it like this, using a direct URL everything works fine.
        string parameters = @"key=1b9189df79bf3f8dff2125c22834210903&image=http://static.reddit.com/reddit.com.header.png"; //Convert.ToBase64String(x);
        WebRequest webRequest = WebRequest.Create(new Uri("http://imgur.com/api/upload"));

        webRequest.ContentType = "application/x-www-form-urlencoded";
        webRequest.Method = "POST";
        byte[] bytes = Encoding.ASCII.GetBytes(parameters);

        Stream os = null;
        try
        { // send the Post
            webRequest.ContentLength = bytes.Length;   //Count bytes to send
            os = webRequest.GetRequestStream();
            os.Write(bytes, 0, bytes.Length);         //Send it
        }
        catch (WebException ex)
        {
            MessageBox.Show(ex.Message, "HttpPost: Request error");

        }
        finally
        {
            if (os != null)
            {
                os.Close();
            }
        }

        try
        { // get the response
            WebResponse webResponse = webRequest.GetResponse();

            StreamReader sr = new StreamReader(webResponse.GetResponseStream());
            MessageBox.Show(sr.ReadToEnd().Trim());
        }
        catch (WebException ex)
        {
            MessageBox.Show(ex.Message, "HttpPost: Response error");                  
        }            

    }

Now, the things I noticed is that when I changed my API key in the parameters string to "239231" or whatever number, the response I got was: "Invalid API key." So I think something must be working right.

I placed my correct API key and now I get a different response: "Invalid image format. Try uploading a JPEG image."

The service I'm using accepts almost every image format, so I am 100% certain the error is in the way I'm sending the file. Can anyone shed some light?

EDIT!!!

It turns out when I upload a JPG image I get that gray box thing. If I upload a big jpg image I don't get anything. For example: https://i.sstatic.net/8Y4uB.jpg

When I upload PNG's, the image uploaded doesn't even show.

I'm certain the issue is the encoding. What can I do?

EDIT 2!!!

Now I'm 100% certain that the problem lies in the first line of the method. The File.ReadAllBytes() must be doing something wrong. If I upload a URL file, every works peachy: https://i.sstatic.net/clcmZ.png

I wonder what encoding I should use. :S

Try using a tool such as Fiddler to see how the data is POSTed, when the code executes from Python. And, see how the request is sent alongwith data when done from .net. That should help you find the difference & fix the later. — shahkalpesh
– shahkalpesh, Commented Jan 12, 2010 at 5:42

Rubens Farias · Accepted Answer · 2010-01-11 18:44:13Z

3

Try this:

string file = @"C:\Users\Sergio\documents\visual studio 2010\Projects\WpfApplication1\WpfApplication1\Test\Avatar.png";
string parameters = @"key=1df918979bf3f8dff2125c22834210903&image=" +
    Convert.ToBase64String(File.ReadAllBytes(file));

answered Jan 11, 2010 at 18:44

Rubens Farias

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9 Comments

Sergio Tapia Over a year ago

This worked, somewhat. I think I'm sending the file before I complete reading all the bytes because I recieve this image: i.imgur.com/hXIfq.jpg

Rubens Farias Over a year ago

maybe you should ask to your API provider, or your current image is broken, or try to upload a JPEG image

Sergio Tapia Over a year ago

I don't know what's going wrong with the upload. Check this image out: i.imgur.com/y0WVP.jpg If you notice, the top has a bit of image, maybe I'm closing the connection too soon? How can I check this?

Sergio Tapia Over a year ago

I get a response OK, which is the expected response and it even gives me the link of the uplaoded image. I think the problem is in the encoding of the image. :S

Rubens Farias Over a year ago

FileInfo fi = new FileInfo(path); byte[] content = new byte[(int)fi.Length]; new FileStream(path, FileMode.Open).Read(content, 0, content.Length);

|

Community · Accepted Answer · 2017-05-23 10:27:37Z

3

You should correctly form a multipart POST request. See an example here: Upload files with HTTPWebrequest (multipart/form-data)

edited May 23, 2017 at 10:27

CommunityBot

11 silver badge

answered Jan 11, 2010 at 19:59

VladV

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2 Comments

Ruben Bartelink Over a year ago

Can clever -1ers please give a justification? +1ing to balance.

Nyerguds Over a year ago

Yeah, definitely use multipart for large stuff like files.

smottt · Accepted Answer · 2015-10-17 07:30:59Z

Read image posted by in API

public IHttpActionResult UpdatePhysicianImage(HttpRequestMessage request)
    {
        try
        {
            var form = HttpContext.Current.Request.Form;
            var model = JsonConvert.DeserializeObject<UserPic>(form["json"].ToString());
            bool istoken = _appdevice.GettokenID(model.DeviceId);
            if (!istoken)
            {
                statuscode = 0;
                message = ErrorMessage.TockenNotvalid;
                goto invalidtoken;
            }
            HttpResponseMessage result = null;
            var httpRequest = HttpContext.Current.Request;
            if (httpRequest.Files.Count > 0)
            {
                var docfiles = new List<string>();
                foreach (string file in httpRequest.Files)
                {
                    var postedFile = httpRequest.Files[file];
                    // var filePath = uploadPath + postedFile.FileName;
                    //  string fileUrl = Utility.AbsolutePath("~/Data/User/" + model.UserId.ToString());
                    string fileUrl = Utility.AbsolutePath("~/" + Utility.UserDataFolder(model.UserId, "Document"));
                    if (!Directory.Exists(fileUrl))
                    {
                        Directory.CreateDirectory(fileUrl);
                        Directory.CreateDirectory(fileUrl + "\\" + "Document");
                        Directory.CreateDirectory(fileUrl + "\\" + "License");
                        Directory.CreateDirectory(fileUrl + "\\" + "Profile");
                    }
                    string imageUrl = postedFile.FileName;
                    string naviPath = Utility.ProfileImagePath(model.UserId, imageUrl);
                    var path = Utility.AbsolutePath("~/" + naviPath);
                    postedFile.SaveAs(path);
                    docfiles.Add(path);
                    if (model.RoleId == 2)
                    {
                        var doctorEntity = _doctorProfile.GetNameVideoChat(model.UserId);
                        doctorEntity.ProfileImagePath = naviPath;
                        _doctorProfile.UpdateDoctorUpdProfile(doctorEntity);
                    }
                    else
                    {
                        var patientEntity = _PatientProfile.GetPatientByUserProfileId(model.UserId);
                        patientEntity.TumbImagePath = naviPath;
                        _PatientProfile.UpdatePatient(patientEntity);
                    }
                }
                result = Request.CreateResponse(HttpStatusCode.Created, docfiles);
            }
            else
            {
                result = Request.CreateResponse(HttpStatusCode.BadRequest);
            }
        }
        catch (Exception e)
        {
            statuscode = 0;
            message = "Error" + e.Message;
        }
    invalidtoken:
        return Json(modeldata.GetData(statuscode, message));
    }

Paul Alan Taylor · Accepted Answer · 2010-01-11 18:42:11Z

0

Try changing :-

"application/x-www-form-urlencoded"

to

"multipart/form-data"

answered Jan 11, 2010 at 18:42

Paul Alan Taylor

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1 Comment

Nyerguds Over a year ago

@SergioTapia You do actually have to send the information as multipart, then.

feroze · Accepted Answer · 2010-01-11 19:10:38Z

0

Try adding the content-type for the jpg into your multipart boundary.

See this uRL for examples (at the end)

http://www.w3.org/TR/html401/interact/forms.html#h-17.13.4.2

answered Jan 11, 2010 at 19:10

feroze

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Comments

cgd · Accepted Answer · 2010-01-12 16:26:35Z

-1

Shot in the dark, but maybe create an instance of Image, save the file to a Stream and use that to read the bytes into an array then upload it.

As in:

Image i = System.Drawing.Image.FromFile("wut.jpg");
Stream stm = new Stream();
System.Drawing.Imaging.Encoder myEncoder = System.Drawing.Imaging.Encoder.Quality;
System.Drawing.Imaging.EncoderParameters paramz = new System.Drawing.Imaging.EncoderParameters(1);
myEncoderParameter = new EncoderParameter(myEncoder, 100L);
paramz.Param[0] = myEncoderParameter;
i.Save(stm, System.Drawing.Imaging.ImageFormat.Jpeg, paramz);
/* I'm lazy: code for reading Stream into byte[] here */

answered Jan 12, 2010 at 16:26

cgd

1

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