How to use WebRequest to POST some data and read response

Question

Need to have the server make a POST to an API  how do I add POST values to a WebRequest object and how do I send it and get the response  it will be a string  out   I need to POST TWO values  and sometimes more  I see in these examples where it says string postData    a string to post   but how do I let the thing I am POSTing to know that there is multiple form values

User · Answer

A more powerful and flexible example can be found here  C  File Upload with form fields  cookies and headers

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From MSDN     Create a request using a URL that can receive a post   WebRequest request   WebRequest Create   http   contoso com PostAccepter aspx        Set the Method property of the request to POST  request Method    POST      Create POST data and convert it to a byte array  string postData    This is a test that posts this string to a Web server    byte   byteArray   Encoding UTF8 GetBytes  postData      Set the ContentType property of the WebRequest  request ContentType    application x-www-form-urlencoded      Set the ContentLength property of the WebRequest  request ContentLength   byteArray Length     Get the request stream  Stream dataStream   request GetRequestStream        Write the data to the request stream  dataStream Write  byteArray  0  byteArray Length      Close the Stream object  dataStream Close        Get the response  WebResponse response   request GetResponse        Display the status  Console WriteLine    HttpWebResponse response  StatusDescription      Get the stream containing content returned by the server  dataStream   response GetResponseStream        Open the stream using a StreamReader for easy access  StreamReader reader   new StreamReader  dataStream      Read the content  string responseFromServer   reader ReadToEnd        Display the content  Console WriteLine  responseFromServer      Clean up the streams  reader Close     dataStream Close     response Close       Take into account that the information must be sent in the format key1 value1 amp key2 value2

User · Answer

Here s what works for me  I m sure it can be improved  so feel free to make suggestions or edit to make it better   const string WEBSERVICE URL    http   localhost projectname ServiceName svc ServiceMethod     This string is untested  but I think it s ok  string jsonData        key1       value1      key2     value2         try              var webRequest   System Net WebRequest Create WEBSERVICE URL       if  webRequest    null                webRequest Method    POST           webRequest Timeout   20000          webRequest ContentType    application json        using  System IO Stream s   webRequest GetRequestStream                  using  System IO StreamWriter sw   new System IO StreamWriter s               sw Write jsonData              using  System IO Stream s   webRequest GetResponse   GetResponseStream                  using  System IO StreamReader sr   new System IO StreamReader s                         var jsonResponse   sr ReadToEnd                System Diagnostics Debug WriteLine String Format  Response   0    jsonResponse                        catch  Exception ex        System Diagnostics Debug WriteLine ex ToString

User · Answer

Here s an example of posting to a web service using the HttpWebRequest and HttpWebResponse objects     StringBuilder sb   new StringBuilder        string query     q     latitude     2C    longitude     amp format xml amp key xxxxxxxxxxxxxxxxxxxxxxxx       string weatherservice    http   api worldweatheronline com free v1 marine ashx    query      HttpWebRequest request    HttpWebRequest WebRequest Create weatherservice       request Referer    http   www yourdomain com       HttpWebResponse response    HttpWebResponse request GetResponse        Stream stream   response GetResponseStream        StreamReader reader   new StreamReader stream       Char   readBuffer   new Char 256       int count   reader Read readBuffer  0  256        while  count  gt  0                String output   new String readBuffer  0  count           sb Append output           count   reader Read readBuffer  0  256             string xml   sb ToString

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Below is the code that read the data from the text file and sends it to the handler for processing and receive the response data from the handler and read it and store the data in the string builder class            Get the data from text file that needs to be sent                  FileStream fileStream   new FileStream   G  Papertest txt   FileMode OpenOrCreate  FileAccess ReadWrite                   byte   buffer   new byte fileStream Length                   int count   fileStream Read buffer  0  buffer Length                      This is a handler would recieve the data and process it and sends back response                  WebRequest myWebRequest   WebRequest Create   http   localhost Provider ProcessorHandler ashx                     myWebRequest ContentLength   buffer Length                  myWebRequest ContentType    application octet-stream                   myWebRequest Method    POST                      get the stream object that holds request stream                  Stream stream   myWebRequest GetRequestStream                           stream Write buffer  0  buffer Length                          stream Close                       Sends a web request and wait for response                  try                                       WebResponse webResponse   myWebRequest GetResponse                          get Stream Data from the response                     Stream respData   webResponse GetResponseStream                          read the response from stream                      StreamReader streamReader   new StreamReader respData                       string name                      StringBuilder str   new StringBuilder                        while   name   streamReader ReadLine       null                                                str Append name      Add to stringbuider when response contains multple lines data                                                        catch  Exception ex                                        throw ex

[c#] How to use WebRequest to POST some data and read response?

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