How to upload a file with parameters to an external API

Hi Guys,

Today I am going to tell you how to upload a file with parameters to an external API. It is quite useful to send information like profile details of a user to an API. To achieve

this there are two ways which I found to implement the same. The first way is using "RestSharp" which is a library used in C# to call API. This is really simple and allows async

calls which is quite prevalant these days. The second way is to create a utility class and then call the post method to send the details with file stream.

  Below are the ways

1. Using RestClient

//First Way Using Nuget Package https://www.nuget.org/packages/RestSharp
//RestRequest for adding parameters
RestRequest request = new RestRequest("http://www.test.com/profiledata.aspx", Method.POST);
request.AddParameter("details", msgTextBox.Text);
request.AddFile("profilepic", Server.MapPath("Myfiles/")+"test.jpg");

//calling server with restClient
RestClient restClient = new RestClient();
restClient.ExecuteAsync(request, (response) =>
{
     if (response.StatusCode == HttpStatusCode.OK)
     {
          //POST successful
  
     }
     else
     {
          //error ocured during POST
     }
});


2. Using Utility Class

a. Create  a utility class as below
    public static class Upload
    {
        private const string FileFieldNameDefault = "fileContent";

        public static WebResponse PostFile
            (Uri requestUri, NameValueCollection postData, Stream fileData, string fileName,
             string fileContentType, string fileFieldName, CookieContainer cookies,
             NameValueCollection headers)
        {
            ServicePointManager.Expect100Continue = false;

            if (requestUri.Scheme == "https")
            {
                ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;

                ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, err) => true;
            }

            var webRequest = (HttpWebRequest)WebRequest.Create(requestUri);

            webRequest.Method = "POST";

            string boundary = "----------" + DateTime.Now.Ticks.ToString("x", CultureInfo.InvariantCulture);

            webRequest.ContentType = "multipart/form-data; boundary=" + boundary;

            string ctype;

            if (string.IsNullOrEmpty(fileContentType))
                fileContentType = TryGetContentType(fileName, out ctype)
                                    ? ctype
                                    : "application/octet-stream";

            fileFieldName = string.IsNullOrEmpty(fileFieldName) ? FileFieldNameDefault : fileFieldName;

            if (headers != null)
                foreach (string key in headers.AllKeys)
                {
                    var values = headers.GetValues(key);
                    if (values != null)
                        foreach (var value in values)
                            webRequest.Headers.Add(key, value);
                }

            if (cookies != null)
                webRequest.CookieContainer = cookies;

            var sbHeader = new StringBuilder();

            if (fileData != null)
            {
                var fileNameValue = string.Empty;

                if (string.IsNullOrEmpty(fileName) == false)
                    fileNameValue = string.Format(CultureInfo.InvariantCulture, "filename=\"{0}\"", Path.GetFileName(fileName));

                sbHeader
                    .AppendFormat("--{0}", boundary)
                    .AppendLine()
                    .AppendFormat("Content-Disposition: form-data; name=\"{0}\"; {1}", fileFieldName, fileNameValue)
                    .AppendLine()
                    .AppendFormat("Content-Type: {0}", fileContentType)
                    .AppendLine()
                    .AppendLine();
            }

            var sbFooter = new StringBuilder();
            sbFooter.AppendLine();

            if (postData != null)
                foreach (var key in postData.AllKeys)
                {
                    var values = postData.GetValues(key);
                    if (values != null)
                        foreach (var value in values)
                            sbFooter
                                .AppendFormat("--{0}", boundary)
                                .AppendLine()
                                .AppendFormat("Content-Disposition: form-data; name=\"{0}\"", key)
                                .AppendLine()
                                .AppendLine()
                                .Append(value)
                                .AppendLine();
                }

            sbFooter.AppendFormat("--{0}--\r\n", boundary);

            byte[] header = Encoding.UTF8.GetBytes(sbHeader.ToString());
            byte[] footer = Encoding.UTF8.GetBytes(sbFooter.ToString());
            long contentLength = header.Length + (fileData != null ? fileData.Length : 0) + footer.Length;

            webRequest.ContentLength = contentLength;

            using (var requestStream = webRequest.GetRequestStream())
            {
                requestStream.Write(header, 0, header.Length);

                if (fileData != null)
                {
                    var buffer = new byte[4096];
                    int bytesRead;
                    while ((bytesRead = fileData.Read(buffer, 0, buffer.Length)) != 0)
                        requestStream.Write(buffer, 0, bytesRead);
                }

                requestStream.Write(footer, 0, footer.Length);

                return webRequest.GetResponse();
            }
        }

        public static WebResponse PostFile
            (Uri requestUri, NameValueCollection postData, string fileName,
             string fileContentType, string fileFieldName, CookieContainer cookies,
             NameValueCollection headers)
        {
            using (var fileData = File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                return PostFile(requestUri, postData, fileData,
                                fileName, fileContentType, fileFieldName, cookies,
                                headers);
        }

        private static bool TryGetContentType(string fileName, out string contentType)
        {
            try
            {
                RegistryKey key = Registry.ClassesRoot.OpenSubKey(@"MIME\Database\Content Type");

                if (key != null)
                {
                    foreach (string keyName in from keyName in key.GetSubKeyNames()
                                               let subKey = key.OpenSubKey(keyName)
                                               where subKey != null
                                               let subKeyValue = (string)subKey.GetValue("Extension")
                                               where string.IsNullOrEmpty(subKeyValue) == false
                                               where string.Compare(Path.GetExtension(fileName), subKeyValue, StringComparison.OrdinalIgnoreCase) == 0
                                               select keyName)
                    {
                        contentType = keyName;
                        return true;
                    }
                }
            }
            catch
            {
                // fail silently
                // TODO: rethrow registry access denied errors
            }
            contentType = string.Empty;
            return false;
        }
    }

b. call the api using this example

//Thanks to http://stackoverflow.com/questions/7382786/uploading-a-file-using-application-x-www-form-urlencoded

            //Get the file name and save it in a stream
            string filename = Server.MapPath("~/ProfileFile/sampleCSV.csv");
            FileStream fileData = new FileStream(filename, FileMode.Open, FileAccess.Read);

            //Add the form values in the collection
            NameValueCollection frmValues = new NameValueCollection();
            frmValues.Add("method", "myUpload");
            frmValues.Add("userid", "xxxxxxxxx");
            frmValues.Add("password", "xxxxxxxx");
            frmValues.Add("xlsFile", filename);

            //Get the path of the target url
            Uri u=new Uri("http://www.test.com/GatewayAPI/rest");

            //Get the name value collection of headers
            //NameValueCollection headers = base.Request.Headers;
            NameValueCollection headers = null;

            //Post the data
            Upload.PostFile(u, frmValues, fileData, filename, "text/csv", "xlsFile", null, headers);


Thanks and Enjoy!!