Post form data to another URL in ASP.NET 1.1

baoshenyi

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16 Jan 20073 min read

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I am a web developer. I worked for oil company in China before I came to Canada.

Introduction<o:p>

I need post form data to another URL in ASP.NET 1.1. After I searched it on internet, I found following methods. <o:p>

1. Use "Response.Clear()", "Response.Write()" and "Response.End()". It could post data to same page, but it could not post data to URL in a new window. Also I will will break "Back" button in browser. <o:p>

2. Use HttpWebRequestion and HttpWebResponse to send request to server and get reponse. It returnes all page information in HTML. So we have to go through HTML to find useful data. <o:p>

3. Post form data using Javascript. But I could not use it in user control, since I could not create multiple forms dynamically.<o:p>

Demo Codes<o:p>

I would like give some demo codes for 3 methos as following,<o:p>

1. <o:p>

public class RemotePost
{
private System.Collections.Specialized.NameValueCollection Inputs = new System.Collections.Specialized.NameValueCollection();

public string Url = "";
public string Method = "post";
public string FormName = "form1";

public void Add(string name,string value)
{
Inputs.Add(name,value);
}

public void Post()
{
System.Web.HttpContext.Current.Response.Clear();

System.Web.HttpContext.Current.Response.Write("<html><head>");

System.Web.HttpContext.Current.Response.Write(string.Format("</head><body onload=\"document.{0}.submit()\">",FormName));
System.Web.HttpContext.Current.Response.Write(string.Format("<form name=\"{0}\" method=\"{1}\" action=\"{2}\" >",FormName,Method,Url));
for(int i=0;i< Inputs.Keys.Count;i++)
{
System.Web.HttpContext.Current.Response.Write(string.Format("<input name=\"{0}\" type=\"hidden\" value=\"{1}\">",Inputs.Keys[i],Inputs[Inputs.Keys[i]]));
}
System.Web.HttpContext.Current.Response.Write("</form>");
System.Web.HttpContext.Current.Response.Write("</body></html>");

System.Web.HttpContext.Current.Response.End();
}
}

In ASP.NET:

RemotePost m = new RemotePost();
m.Url = "test.aspx";

m.Add( "para1" ,"123456" );
m.Add( "para2" ,"0001" );
m.Post();

Please pay attention on "onload" event, form will be posted automatically.<o:p>

<o:p>

2.http://authors.aspalliance.com/stevesmith/articles/netscrape2.asp <o:p>

/stevesmith/articles/examples/cs/postscrape.aspx<o:p>

<%@ Import Namespace="System.Net" %>

<%@ Import Namespace="System.IO" %>

<script language="C#" runat="server">

   void Page_Load(Object Src, EventArgs E) {

      myPage.Text = readHtmlPage("http://aspalliance.com/aldotnet/examples/posttest.asp");

   }

   private String readHtmlPage(string url)

   {

      String result = "";

      String strPost = "x=1&y=2&z=YouPostedOk";

      StreamWriter myWriter = null;



      HttpWebRequest objRequest = (HttpWebRequest)WebRequest.Create(url);

      objRequest.Method = "POST";

      objRequest.ContentLength = strPost.Length;

      objRequest.ContentType = "application/x-www-form-urlencoded";



      try

      {

         myWriter = new StreamWriter(objRequest.GetRequestStream());

         myWriter.Write(strPost);

      }

      catch (Exception e)

      {

         return e.Message;

      }

      finally {

         myWriter.Close();

      }



      HttpWebResponse objResponse = (HttpWebResponse)objRequest.GetResponse();

      using (StreamReader sr =

         new StreamReader(objResponse.GetResponseStream()) )

      {

         result = sr.ReadToEnd();

         // Close and clean up the StreamReader

         sr.Close();

      }

      return result;

   }

</script>

<html>

<body>

<b>This content is being populated from a separate HTTP request to

<a href="http://aspalliance.com/aldotnet/examples/posttest.asp">

http://aspalliance.com/aldotnet/examples/posttest.asp</a>:</b><hr/>

<asp:literal id="myPage" runat="server"/>

</body>

</html><o:p>

<o:p>

3. http://www.codeproject.com/aspnet/jsnopostback.asp<o:p>

<div id="Content" name="Content"><o:p>

    <form method="post" id="Form1" runat="server"><o:p>

<o:p>

    </form><o:p>

</div><o:p>

The JavaScript now needs to differentiate between Netscape 4 and the other DOM aware browsers. Check for document.layers to identify Netscape 4, and simply use the syntax appropriate for that browser:<o:p>

<script language="javascript"><o:p>

<o:p>

</script><o:p>

<o:p>

<o:p>

Improvement.<o:p>

<o:p>

My coworker gave me some good ideas, I choose 3rd method and improve it as my solution. Everytime, form and hidden fields are created dynamically, so it could handle form and fields as many as I wish. Also it could be used in user control, since all function is done on client side.<o:p>

<o:p>

//Creat form dynamically and post data to specified URL
//formName: the name of form
//formAction: the URL
//hidden input fields, like fieldname1=fieldvalue1&fieldname2=fieldvalue2
function postForm(formName,formAction,arrayStr,newWindow)
{
var frm=cf(formName,formAction,newWindow);
var inputArray=arrayStr.split('&');
for(var j=0;j<inputArray.length;j++)
{
var temp=inputArray[j].split('=');
if(isArray(temp) && temp.length==2)
{
cfi(frm,temp[0],temp[1])
}
}
frm.submit();
}
//Check whether variable is array
function isArray(obj) {
if (obj.constructor.toString().indexOf('Array') == -1)
return false;
else
return true;
}
function cf(name,action,newWindow) {
var f = document.createElement('FORM');
f.method='POST';
f.name=name;
f.action=action;
if(newWindow)
f.target='_blank';
document.body.appendChild(f);
return f;
}
function cfi(parentForm,name,value) {
var i = document.createElement('INPUT');
i.type='hidden';
i.name=name;
i.value=value;
parentForm.appendChild(i);
}<o:p>

<o:p>

in ASP.NET,<o:p>

HyperLink hl;<o:p>

string arrStr="fieldname1=fieldvalue1&fieldname2=fieldvalue2";<o:p>

hl.NagativeUrl="#";<o:p>

hl.Attributes.Add("onclick","postForm('PostedData','getpost.aspx','"+arrStr+"',true);return false;");<o:p>

<o:p>

If anyone knows how to implement same function on server side, please let me know. Thanks.<o:p>

<o:p>

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Written By

baoshenyi

Web Developer

Canada

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Post form data to another URL in ASP.NET 1.1

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