Post form data using HttpWebRequest

Question

I want to post some form data to a specified URL that isn t inside my own web application  It has the same domain  such like  domain client nl   The web application has a url  web domain client nl  en the url where I want to post to is  idp domain client nl    But my code does nothing      does someone knows what I m doing wrong    Wouter  StringBuilder postData   new StringBuilder    postData Append HttpUtility UrlEncode String Format  username  0  amp    uname     postData Append HttpUtility UrlEncode String Format  password  0  amp    pword     postData Append HttpUtility UrlEncode String Format  url success  0  amp    urlSuccess     postData Append HttpUtility UrlEncode String Format  url failed  0    urlFailed      ASCIIEncoding ascii   new ASCIIEncoding    byte   postBytes   ascii GetBytes postData ToString         set up request object HttpWebRequest request  try       request    HttpWebRequest HttpWebRequest Create WebSiteConstants UrlIdp     catch  UriFormatException        request   null    if  request    null      throw new ApplicationException  Invalid URL      WebSiteConstants UrlIdp    request Method    POST   request ContentType    application x-www-form-urlencoded   request ContentLength   postBytes Length  request UserAgent    Mozilla 4 0  compatible  MSIE 6 0  Windows NT 5 1  SV1   NET CLR 1 1 4322   NET CLR 2 0 50727        add post data to request Stream postStream   request GetRequestStream    postStream Write postBytes  0  postBytes Length   postStream Flush    postStream Close

User · Answer

Both the field name and the value should be url encoded. format of the post data and query string are the same

The .net way of doing is something like this

NameValueCollection outgoingQueryString = HttpUtility.ParseQueryString(String.Empty);
outgoingQueryString.Add("field1","value1");
outgoingQueryString.Add("field2", "value2");
string postdata = outgoingQueryString.ToString();

This will take care of encoding the fields and the value names

User · Answer

Try this   var request    HttpWebRequest WebRequest Create  http   www example com recepticle aspx     var postData    thing1 hello       postData      amp thing2 world   var data   Encoding ASCII GetBytes postData    request Method    POST   request ContentType    application x-www-form-urlencoded   request ContentLength   data Length   using  var stream   request GetRequestStream          stream Write data  0  data Length      var response    HttpWebResponse request GetResponse     var responseString   new StreamReader response GetResponseStream    ReadToEnd

User · Answer

Use this code  internal void SomeFunction         Dictionary lt string  string gt  formField   new Dictionary lt string  string gt              formField Add  quot Name quot    quot Henry quot        formField Add  quot Age quot    quot 21 quot             string body   GetBodyStringFromDictionary formField          output   Name Henry amp Age 21    internal string GetBodyStringFromDictionary Dictionary lt string  string gt  formField        string body   string Empty      foreach  var pair in formField                body      quot  pair Key   pair Value  amp  quot                    delete last  quot  amp  quot      body   body Substring 0  body Length - 1        return body

User · Answer

You are encoding the form incorrectly  You should only encode the values   StringBuilder postData   new StringBuilder    postData Append  username     HttpUtility UrlEncode uname      amp     postData Append  password     HttpUtility UrlEncode pword      amp     postData Append  url success     HttpUtility UrlEncode urlSuccess      amp     postData Append  url failed     HttpUtility UrlEncode urlFailed      edit   I was incorrect  According to RFC1866 section 8 2 1 both names and values should be encoded   But for the given example  the names do not have any characters that needs to be encoded  so in this case my code example is correct     The code in the question is still incorrect as it would encode the equal sign which is the reason to why the web server cannot decode it   A more proper way would have been   StringBuilder postData   new StringBuilder    postData AppendUrlEncoded  username   uname   postData AppendUrlEncoded  password   pword   postData AppendUrlEncoded  url success   urlSuccess   postData AppendUrlEncoded  url failed   urlFailed      in an extension class public static void AppendUrlEncoded this StringBuilder sb  string name  string value        if  sb Length    0          sb Append   amp         sb Append HttpUtility UrlEncode name        sb Append           sb Append HttpUtility UrlEncode value

[c#] Post form data using HttpWebRequest

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