Email Server Control
Introduction:
We all have used Web Server
Controls like datagrid, textboxes, buttons and calendars. But have you ever
thought of making your own custom web server control. In this article we will
develop a very simple email server control that will let you send emails to the
users with a static message.
Getting started:
For making web server controls you need to
select the Web Server project. You can select the Web control Library project as
it can be seen in the picture below:
Okay, this will open a new file which has many
lines of code already written for you. Don't worry about those lines yet I will
explain all of it later.
Email Server Control Look:
let's take a look at the UI of the Email Server
control when it will be finished.
As, you see that this is fairly simple email
control which only consists of a button and a textbox. It does not gives you the
ability to write the message or the body since those of them are kept constant
in this example. The cool thing is that when you drag and drop the control on
your webform it will be displayed exactly the same way as in the picture above
which means that this control will have the design time appearance and a
designer attached to it.
|
[
Designer(typeof(EmailControl.CompositeControlDesigner))
]
|
This is an attribute that associates the designer for
this control. We will see the designer later in this article.
Email Server Control Code:
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private Button _button;
private TextBox _emailTextBox;
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Next we created two controls. Once is a textbox and one
is a button control. Since our Email control will be made of two different
controls it is called composite control.
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public override
ControlCollection Controls
{
get
{
EnsureChildControls();
return base.Controls;
}
}
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Here we check that the child controls are created and
added to the control tree.
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protected
override void CreateChildControls()
{
Controls.Clear();
_emailTextBox = new
TextBox();
_emailTextBox.ID = "emailTextBox";
_button = new
Button();
_button.ID = "EmailButton";
_button.Text = "Send Email";
_button.Click +=new
EventHandler(_button_Click);
this.Controls.Add(_emailTextBox);
this.Controls.Add(_button);
}
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This is where the controls are actually made and added
to the control tree. We are simply making the textbox controls as well as the
button controls and we attach a button click event with the button controls and
finally add the control in the control tree. As you can see the _emailTextBoxID
is assigned a new id. Every control on the form must have a different id or else
it will generate errors.
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protected
override void
Render(HtmlTextWriter writer)
{
_emailTextBox.RenderControl(writer);
_button.RenderControl(writer);
}
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The render method is used to render the controls on the
screen. We are rendering the textbox as well as button control. You can also use
various html tags to make your rendering more attractive.
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private void _button_Click(object
sender, EventArgs e)
{
MailMessage mail = new
MailMessage();
mail.To = _emailTextBox.Text;
mail.From = "testmail@tester.com";
mail.Subject = "Hello";
mail.Body = "Hello World";
try
{
SmtpMail.SmtpServer = "localhost";
SmtpMail.Send(mail);
_button.Text = "Mail Sent";
}
catch(Exception
ex)
{
_emailTextBox.Text = ex.Message;
}
}
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This is the code to send email which I have already
explained in my previous articles like http://www.codersource.net/csharp_sending_emails.aspx. If you encounter any problems while sending
emails you can visit
www.msdn.microsoft.com .
The Visual Composite Control Designer:
Visual Composite Control Designer class allow us to
actually see the visual appearance of our control when we drag it on the form.
Let's see the designer class in detail.
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using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Web.UI;
using System.Web.UI.Design;
namespace EmailControl {
public
class
CompositeControlDesigner : ControlDesigner {
public
override
string GetDesignTimeHtml()
{
// Retrieve the controls to ensure they
are created.
ControlCollection controls = ((Control)Component).Controls;
return
base.GetDesignTimeHtml();
}
public
override
void Initialize(IComponent
component) {
if (!(component
is Control) &&
!(component is
INamingContainer)) {
throw
new ArgumentException(
"Component must be a container control.", "component");
}
base.Initialize(component);
}
}
}
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The designer class mainly uses the GetDesignTimeHTML()
method to get the html of all the controls on the form. We use an attribute to
denote out designer class. If you don't specify your control designer than you
control can appear as text or also as nothing depending what you render in the
render method. Its always nice to have a designer which gives the user more idea
what they are dealing with.
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[
Designer(typeof(EmailControl.CompositeControlDesigner))
]
|
Project attached with this Article:
There is a project attached with this article. All you
need to do to use the email Server control is to reference the dynamic link
library file in your project. Once the dll has been referenced you can add the
control by simply dropping it on the form.
I hope you liked the article Happy programming !
If you have further questions please email Azam
at azamsharp@gmail.com
Attachments:
Project Files: EmailControl_azam.zip