The C# application HTMLFormData collects data that will be used to fill the contents of an HTML Form, named FormToBeFilled. For this example, I choose to collect three pieces of information (name, state, and date) and provide them to FormToBeFilled. Javascript in the form will use the values to initialize three elements (also name, state, and date).
The C# application's form contains: TextBox name_TB, ComboBox state_CB, DateTimePicker date_DTP, Button revise_data_BUT, and Button exit_BUT. There are labels that label each of the first three components.
It is assumed that FormToBeFilled exists on a server. In the same directory as FormToBeFilled must also exist the output of HTMLFormData which, for this example, will be called CToHTML.txt. This is the AGREED_FILENAME. HTMLFormData writes to this file; FormToBeFilled reads from this file.
There is nothing really special about HTMLFormData. Its source follows. The complete project, including FormToBeFilled, can be found at FillHTMLFromCSharp.zip (9.5 KB).
using System;
using System.IO;
using System.Text;
using System.Windows.Forms;
namespace FillHTMLFromCSharp
{
public partial class HTMLFormData : Form
{
const string AGREED_FILENAME = @"C:\Users\Public\CToHTML.txt";
protected override void OnFormClosing (
FormClosingEventArgs e )
{
base.OnFormClosing(e);
}
public HTMLFormData ( )
{
InitializeComponent ( );
}
void revise_data_file ( )
{
string date = date_DTP.Text;
string message = String.Empty;
string name = name_TB.Text;
object provided_state = state_CB.SelectedItem;
string state = String.Empty;
if ( String.IsNullOrEmpty ( name ) )
{
message = "A name must be provided";
}
if ( provided_state == null )
{
if ( !String.IsNullOrEmpty ( message ) )
{
message += Environment.NewLine;
}
message += "A state must be provided";
}
else
{
state = provided_state.ToString ( );
}
if ( String.IsNullOrEmpty ( message ) )
{
using ( StreamWriter sw = new StreamWriter (
AGREED_FILENAME,
false ) )
{
StringBuilder sb = new StringBuilder ( );
sb.AppendFormat ( "{0},{1},{2}",
name,
date,
state );
sw.Write ( sb.ToString ( ));
}
}
else
{
MessageBox.Show ( message,
"Input Error" );
}
}
void BUT_Click ( object sender, EventArgs e )
{
Button button = ( Button ) sender;
string tag = button.Tag.ToString ( ).
ToLower ( ).
Trim ( );
switch ( tag )
{
case "exit":
Application.Exit ( );
break;
case "revise_data":
revise_data_file ( );
break;
default:
throw new ApplicationException (
"Unrecognized button pressed" );
}
}
}
}
Two items of interest:
- The CToHTML.txt file is placed in the C:\Users\Public\ directory. That allows the program to be run by anyone from anywhere without a security issue. After HTMLFormData completes its execution, the CToHTML.txt file must be copied to the directory in which FormToBeFilled is found. When deployed, the constant AGREED_FILENAME should be modified to point to that same directory, thereby making the copy unnecessary.
- When writing to the CToHTML.txt file, do not use a StreamWriter WriteLine that places a <cr><lf> at the end of the line. This will cause problems in the Javascript that is to parse the data. Rather use a StreamWriter Write.
For expediency, I included the Javascript within FormToBeFilled. The Javascript executes on window load. FormToBeFilled appears as:
<!DOCTYPE HTML PUBLIC
"-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title></title>
</head>
<body>
<form action="">
<table cellpadding="10" cellspacing="0">
<tr>
<td align="right">
Name
</td>
<td align="left">
<input id="name"
type="text"
style="width: 200px;"
maxlength="100"
title="Enter your name"
value="foo" />
</td>
</tr>
<tr>
<td align="right">
State
</td>
<td align="left">
<select id="states">
<option value="AL">AL</option>
<option value="AK">AK</option>
<option value="AZ">AZ</option>
<option value="AR">AR</option>
<option value="CA">CA</option>
<option value="CO">CO</option>
<option value="CT">CT</option>
<option value="DC">DC</option>
<option value="DE">DE</option>
<option value="FL">FL</option>
<option value="GA">GA</option>
<option value="HI">HI</option>
<option value="ID">ID</option>
<option value="IL">IL</option>
<option value="IN">IN</option>
<option value="IA">IA</option>
<option value="KS">KS</option>
<option value="KY">KY</option>
<option value="LA">LA</option>
<option value="ME">ME</option>
<option value="MD">MD</option>
<option value="MA">MA</option>
<option value="MI">MI</option>
<option value="MN">MN</option>
<option value="MS">MS</option>
<option value="MO">MO</option>
<option value="MT">MT</option>
<option value="NE">NE</option>
<option value="NV">NV</option>
<option value="NH">NH</option>
<option value="NJ">NJ</option>
<option value="NM">NM</option>
<option value="NY">NY</option>
<option value="NC">NC</option>
<option value="ND">ND</option>
<option value="OH">OH</option>
<option value="OK">OK</option>
<option value="OR">OR</option>
<option value="PA">PA</option>
<option value="RI">RI</option>
<option value="SC">SC</option>
<option value="SD">SD</option>
<option value="TN">TN</option>
<option value="TX">TX</option>
<option value="UT">UT</option>
<option value="VT">VT</option>
<option value="VA">VA</option>
<option value="WA">WA</option>
<option value="WV">WV</option>
<option value="WI">WI</option>
<option value="WY">WY</option>
</select>
</td>
</tr>
<tr>
<td align="right">
Date
</td>
<td align="left">
<input id="date"
type="text"
style="width: 200px;"
maxlength="100"
title="Enter the date"
value="bar" />
</td>
</tr>
</table>
</form>
<script type="text/javascript">
window.onload = init;
function init ( )
{
if ( window.XMLHttpRequest )
{
xmlhttp=new XMLHttpRequest ( );
}
else
{
xmlhttp=new ActiveXObject ( "Microsoft.XMLHTTP" );
}
xmlhttp.open ( "GET", "CToHTML.txt", false );
xmlhttp.send ( null );
response = xmlhttp.responseText;
var items = response.split ( "," );
document.getElementById ( "name" ).value = items [ 0 ];
document.getElementById ( "date" ).value = items [ 1 ];
var state = items [ 2 ];
var states = document.getElementById ( "states" );
var options = states.options;
for ( var i = 0; ( i < options.length ); i++ )
{
if ( options.item ( i ).innerHTML == state )
{
states.selectedIndex = i;
break;
}
}
}
</script>
</body>
</html>
Hope that helps.
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