Recently we received a support ticket with a question whether RadHtmlPlaceholder provides support for cookies. By default, RadHtmlPlaceholder doesn't have a mechanism for reading/writing cookies. However, with the right bits of JavaScript, everything is possible :)
Imagine you have an HTML page which you want to read/write cookies to and all this has to happen from Silverlight.
First, you need few JavaScript methods for reading/writing cookies. Let's call the page we want to read/write cookies to CookiesPage.html.
<html>
<head>
<title>Cookies Page</title>
<script type="text/javascript">
// Create a cookie with the specified name and value
function SetCookie(name, value) {
document.cookie = name + "=" + value;
alert("Cookie successfully set");
}
// Retrieve the value of the cookie with the specified name
function GetCookie(cookieName) {
// cookies are separated by semicolons
var allCookies = document.cookie.split("; ");
for (var i = 0; i < allCookies.length; i++) {
// a name/value pair (a crumb) is separated by an equal sign
var currentCookieName = allCookies[i].split("=");
if (cookieName == currentCookieName[0])
return allCookies[i];
}
// a cookie with the requested name does not exist
return null;
}
// Retrieve all cookies
function GetAllCookies() {
var allCookies = document.cookie.split("; ");
return allCookies;
}
</script>
</head>
<body bgcolor="aqua">
<h1>Cookies page</h1>
</body>
Next, the Silverlight part. On the page, you need several TextBox controls for reading/writing cookies and a RadHtmlPlaceholder for displaying the HTML page that contains the cookies.
The code-behind approach is pretty simple. Execute the JavaScript methods using RadHtmlPlaceholder's IFrame.
public MainPage()
{
InitializeComponent();
// Get the IFrame from the HtmlPresenter
HtmlElement iframe = (HtmlElement)htmlPlaceholder1.HtmlPresenter.Children[0];
// Set an ID to the IFrame so that can be used later when calling the javascript
iframe.SetAttribute("id", "myIFrame");
}
// Writes a cookie
private void SetCookie()
{
// Define a name for the cookie
var name = this.txtSetCookieName.Text;
// Define a value for the cookie
var value = this.txtSetCookieValue.Text;
// Call the SetCookie(name,value) JavaScript method
string code = string.Format("document.getElementById('myIFrame').contentWindow.SetCookie('{0}','{1}')", name, value);
HtmlPage.Window.Eval(code);
}
// Gets a cookie
private void GetCookie()
{
// Get the name of the cookie we're looking for
string name = this.txtGetCookieName.Text;
// Call the GetCookie(name) JavaScript method
string code = string.Format("document.getElementById('myIFrame').contentWindow.GetCookie('{0}')", name);
var result = HtmlPage.Window.Eval(code);
// Get the value of the cookie and display it
var value = result.ToString().Split('=')[1];
MessageBox.Show("Value: " + value);
}
// Gets all cookies
private void GetAllCookies()
{
// Call the GetAllCookies JavaScript method to retrieve all cookies
string code = "document.getElementById('myIFrame').contentWindow.GetAllCookies()";
// Display the result in a ListBox
ScriptObject result = HtmlPage.Window.Eval(code) as ScriptObject;
int i = 0;
this.cookies.Clear();
while (result.GetProperty(i) != null)
{
this.cookies.Add(result.GetProperty(i) as string);
i++;
}
}
That's it. You can take a look at the video which demonstrates the application or you can download the sample project bellow.
CookiesSupport.zip
RadControls for Silverlight