Python至.net Web服务映像已创建但已损坏

Question

I am sending an image and other parameters from python to a web service (.net) endpoint. While I convert it to byte and then write to disk, the image created can not be displayed... error is 'the image can not displayed because it contains error'. Here is my code in python...

def upload_form():
    header = {'Content-Type':'application/json'}
    params = {'imagefile':bx64, 'sacid':'3', 'astid':'188', 'docName':'abc4', 'docExtn':'png'}
    url='http://localhost:47176/snapshot.svc/DoUpload'
    selector =''

    try:
        _data = dumps(params)           
        req = request.Request(url)
        connection = http.client.HTTPConnection(req.host)
        connection.request ('POST', req.selector, _data, header)
        response = connection.getresponse()
        print('response = %s', response.read())
    except Exception as e:
        print('Error...', e)

bx64 = get_b64string('some png file name')

def get_b64string(file):
    ENCODING = 'utf-8'

    with open(file, 'rb') as open_file:
        return b64encode(open_file.read()).decode(ENCODING)

While at server side, endpoint code is...

    public string DoUpload(string imagefile, string sacid, string astid, string docName, string docExtn)
    {
        string m_fileName = string.Format("{0}.{1}", docName, docExtn.Replace(".", ""));
        string m_host = string.Format("{0}/{1}", FTPUrl, sacid.ToString());

        try
        {
            byte[] imgbinaryarray = Encoding.UTF8.GetBytes(imagefile);
            if (UploadToFtp(imgbinaryarray, FTPUrl, Convert.ToInt32(sacid), Convert.ToInt32(astid), m_fileName)) return "OK";
        }
        catch (Exception ex)
        {
            //Log and return error                
            return ex.Message;
        }
        return "File could not be processed, contact application support!";
    }

Edited: I have modified the code to use 'requests' library in python and also the end point accordingly.

End Point:

    [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.WrappedRequest, ResponseFormat = WebMessageFormat.Json)]
    public string DoFileUpload(Stream fileContent)
    {
        string docName = "abc-"+DateTime.Now.Ticks.ToString();
        string m_fileName = string.Format("{0}.jpg",docName);

        string filePath = string.Format("C:\\Temp\\Upload\\{0}", m_fileName);
        try
        {
            using (var fs = new FileStream(filePath, FileMode.Create, FileAccess.Write))
            {
                fileContent.CopyTo(fs);
            }
            return "OK";        
        }
        catch (Exception ex)
        {   
            return ex.Message;
        }
    }

Python Code:

        def upload_form3(fileToUpload):
        try:
            url = 'http://localhost:47176/snapshot.svc/DoFileUpload'
            files = {'fileContent':open(fileToUpload,'rb')}             
            r = requests.post(url, files=files)
            print(r.text)
        except Exception as e:
            print('upload_form3. Error...', e)

Still the file created is showing same error ie can not open file contains error.

Answer 1

Used like you are doing, requests will post a MIME multipart-encoded data, which your .Net side does not expect (it looks like it expects a simple stream, but I don't know .net enough to be sure).

Try with this python client code, it sends the file content as a simple stream:

def upload_form3(fileToUpload):
    try:
        url = 'http://localhost:47176/snapshot.svc/DoFileUpload'  
        with open(fileToUpload,'rb') as finput:
            r = requests.post(url, data=finput)
        print(r.text)
    except Exception as e:
        print('upload_form3. Error...', e)

Answer 2

Thank you all, I am sorry that I came back late. The solution which I used is to read the stream in a memory stream, strip the initial bytes containing meta data / header information. Then write it to file and the image is correctly created.