HttpWebRequest-使用__EVENTTARGET和__EVENTARGUMENT发布

Question

I want to read all content from a website that is using Asp.net GridView contorl with pagination. Now, pagination is done with POST method by Asp.Net grid using __dopostback with required parameters.

I tried to read pagination data using HttpWebRequest with following code but it always throws "500 internal server error."

  public string GetPageData(int page)
    {
        var request = (HttpWebRequest)WebRequest.Create("http://localhost:61141/Default.aspx");
        string postData = "__EVENTTARGET=ctl00$MainContent$GridView1&__EVENTARGUMENT=Page$"+ page;


        request.Method = "POST";
        var bt = System.Text.Encoding.ASCII.GetBytes(postData);
        request.ContentLength = bt.Length;
        request.ContentType = "application/x-www-form-urlencoded";
        request.UserAgent = " Mozilla/4.0 (compatible; MSIE 6; Windows NT 5) ";
        request.KeepAlive = false;
        request.AllowWriteStreamBuffering = true;

        string strResult;
        Stream stream = request.GetRequestStream();
        stream.Write(bt, 0, bt.Length);
        stream.Close();

        var response = request.GetResponse();
        var sr = new StreamReader(response.GetResponseStream(), true);
        strResult = sr.ReadToEnd();

        return strResult;
    }

Please suggest any workaround over it. Thanks in advanced.

Answer 1

WebForms pagination relies on JavaScript so is intended to be performed within the web browser, not via a custom call as you have here. Why not set up a Web API endpoint or other REST-enabled endpoint in the web application? This has the added benefit that you can return the results as XML or JSON, which removes the need for screen scraping and makes client side processing much easier.