CSharp Cookbook-CSharp Cookbook

Recipe 13.11 Simulating Form Execution

Problem

You need to send a collection of name/value pairs to simulate a form being executed on a browser to a location identified by a URI.

Solution

Use the WebClient class to send a set of name/value pairs to the web server using the UploadValues method. This class enables you to act as the browser executing a form by setting up the name/value pairs with the input data. The input field ID is the name, and the value to use in the field is the value:

using System;
using System.Net;
using System.Text;
using System.Collections.Specialized;

Uri uri = new Uri("http://localhost/FormSim/WebForm1.aspx");
WebClient client = new WebClient( );

// Create a series of name/value pairs to send
NameValueCollection collection = new NameValueCollection( );

// Add necessary parameter/value pairs to the name/value container.
collection.Add("Identity","foo@bar.com");            
collection.Add("Item","Books");            
collection.Add("Quantity","5");            
Console.WriteLine("Uploading name/value pairs to URI {0} ...",
                        uri.AbsoluteUri);                        

// Upload the NameValueCollection.
byte[] responseArray = 
    client.UploadValues(uri.AbsoluteUri,"POST",collection);
// Decode and display the response.
Console.WriteLine("\nResponse received was {0}",
    Encoding.ASCII.GetString(responseArray));

The webform1.aspx page to receive and process this data looks like this:

<%@ Page language="c#" Codebehind="WebForm1.aspx.cs" AutoEventWireup="false" Inherits="FormSim.WebForm1" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
    <HEAD>
        <title>WebForm1</title>
        <meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">
        <meta name="CODE_LANGUAGE" Content="C#">
        <meta name="vs_defaultClientScript" content="JavaScript">
        <meta name="vs_targetSchema" 
              content="http://schemas.microsoft.com/intellisense/ie5">
    </HEAD>
    <body MS_POSITIONING="GridLayout">
        <form id="Form1" method="post" runat="server">
            <asp:TextBox id="Identity" style="Z-INDEX: 101; LEFT: 194px; 
                         POSITION: absolute; TOP: 52px" runat="server"></asp:TextBox>
            <asp:TextBox id="Item" style="Z-INDEX: 102; LEFT: 193px; 
                         POSITION: absolute; TOP: 93px" runat="server"></asp:TextBox>
            <asp:TextBox id="Quantity" style="Z-INDEX: 103; LEFT: 193px; 
                         POSITION: absolute; TOP: 132px"
                runat="server"></asp:TextBox>
            <asp:Button id="Button1" style="Z-INDEX: 104; LEFT: 203px; 
                         POSITION: absolute; TOP: 183px" runat="server"
                Text="Submit"></asp:Button>
            <asp:Label id="Label1" style="Z-INDEX: 105; LEFT: 58px; 
                       POSITION: absolute; TOP: 54px" runat="server"
                Width="122px" Height="24px">Identity:</asp:Label>
            <asp:Label id="Label2" style="Z-INDEX: 106; LEFT: 57px; 
                       POSITION: absolute; TOP: 94px" runat="server"
                Width="128px" Height="25px">Item:</asp:Label>
            <asp:Label id="Label3" style="Z-INDEX: 107; LEFT: 57px; 
                       POSITION: absolute; TOP: 135px" runat="server"
                Width="124px" Height="20px">Quantity:</asp:Label>
        </form>
    </body>
</HTML>

The webform1.aspx code-behind looks like this:

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace FormSim
{
    /// <summary>
    /// Summary description for WebForm1.
    /// </summary>
    public class WebForm1 : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.Button Button1;
        protected System.Web.UI.WebControls.TextBox Item;
        protected System.Web.UI.WebControls.Label Label1;
        protected System.Web.UI.WebControls.Label Label2;
        protected System.Web.UI.WebControls.Label Label3;
        protected System.Web.UI.WebControls.TextBox Identity;
        protected System.Web.UI.WebControls.TextBox Quantity;
    
        private void Page_Load(object sender, System.EventArgs e)
        {
            // Put user code to initialize the page here
        }

        #region Web Form Designer generated code
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: This call is required by the ASP.NET Web Form Designer.
            //
            InitializeComponent( );
            base.OnInit(e);
        }
        
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent( )
        {
            this.Button1.Click += 
                  new System.EventHandler(this.Button1_Click);
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion

        private void Button1_Click(object sender, System.EventArgs e)
        {
            string response = "Thanks for the order!<br/>";
            response += "Identity: " + Request.Form["Identity"] + "<br/>";
            response += "Item: " + Request.Form["Item"] + "<br/>";
            response += "Quantity: " + Request.Form["Quantity"] + "<br/>";
            Response.Write(response);
        }
    }
}

Discussion

The WebClient class makes it easy to upload form data to a web server in the common format of a set of name/value pairs. You can see this technique in the call to UploadValues that takes an absolute URI (http://localhost/FormSim/WebForm1.aspx), the HTTP method to use (POST), and the NameValueCollection we created (collection). The NameValueCollection is populated with the data for each of the fields on the form by giving the id of the input field as the name, and then the value to put in the field as the value during each call to Add. In this example, we fill in the Identity field with foo@bar.com, the Item field with Book, and the Quantity field with 5. We then print out the resulting response from the POST to the console window.

Recipe 13.11 Simulating Form Execution

Problem

Solution

Discussion

See Also